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#33465 - 02/13/16 02:15 PM Double-Wall Enclosure Concept
TCB Offline
Member

Registered: 02/10/16
Posts: 26
Loc: Texas Hill Country
I'd first like to introduce myself and thank the good folks here for hosting this wealth of information, and making it freely available to everyone. I've been frantically reading through as many threads with a low enough jargon-density for me to understand what is going on; I've no formal training whatsoever in framing, but the design philosophy and craftsmanship really appeal to me as an aerospace engineer and amateur machinist. The plan is to learn as much as I can over the next several years as I narrow down the design & build up a war-chest, and by then hopefully have a good idea of what all I will be doing myself vs. hiring specialists/contractors for.

That out of the way, I'd like to pick ya'll's brains about an enclosure/framing concept that seems like it might have some merit. I've been trying to learn about enclosure methods, and just haven't been able to get excited about the daub-styles which seem to require a lot of maintenance & are somewhat limited as far as their design flexibility. Stick-built infill walls w/ plywood or SIPs just feel like cheating. So I looked into wood joinery-based systems, and found this diagram on a TFG thread;

Seemed very simple and straightforward, and seems to have served rather inclimate parts of Europe well enough. But it is ultimately a single layer of wood, to which daub or secondary paneling must be applied in order to get any degree of insulation or draft-seal (not to mention routing paths for conduit in a modern application)

So I wanted to see if there may be a way to adapt it to a double-wall layout;
-Similar to the Swiss style shown above that uses T&G slats stacked horizontally & set into vertical frame grooves to make a wall (Bohlenwand?)
-Instead of trying to use a super-thick timber to put two sets of grooves in to form an insulated cavity, use two parallel (smaller) timbers separated by an air-gap of several inches.
-The inner post carries the inner rafters of a double roof & the upper floor joists; the outer (taller) post carries the exterior rafters
-Columns are tied to eachother with several M&T cross ties along their length, so they function as a single load-bearing member as far as superstructure

Advantages;
-Seems to have all the benefits of a standard 'wall truss' arrangement, but without any thin spot in the insulation at the rafter/wall transition
-Wall can be made arbitrarily thick with about the same qty of timber
-Greatly reduced thermal bridging through the frames by way of conduction; a concern brought up for a super-thick post version
-The cross ties connecting the posts could be made to form a 'tunnel' for vertical wire/plumbing runs
-In my concept, the interior wall is horizontal slats from the ceiling down to about 3ft, where it changes to a system of vertical slats (think wainscotting) that cover horizontal wire/plumbing/ducting routes & can be easily removed/replaced. Above the transition, things are sealed enough that loose insulation can be used, but the actual accessible area uses foam blocks more resilient to infrequent tampering
-Allows for a thick double wall of excellent insulation value, while allowing for exposed timbers on both sides
-Will allow for wall/frame relative movement without loading up the wall boards
-Eliminates the need for plaster or paneling on both sides; can be simple exposed wood slats if desired & designed properly
-I would think is very draft-proof due to the pair of tortuous paths to get past the frames or between the slats
-Potentially the exterior panels could be easily removable/replaceable

Disadvantages;
-Since it relies on two sets of posts, the foundation footing needs to be wide enough to support both (& they'd both need to be tied to the slab/etc.)
-Not sure how the sill would be addressed to keep water from pooling there should water make it to the exterior wall
-High lower limit to how thin the wall buildup can be
-Windows/door frames may need to be an essentially standalone structure coming off the floor plate, since the inner/outer wall can probably shift relative to each other unacceptably. Not sure how different this is than standard practice, though.
-Cost, complexity, etc. which would be a little bit worse than 2X the single wall concept. The smaller timbers could help here, though
-I assume the frame spacing has to be closer than otherwise required for mere strength reasons, so the thin slat panels cannot warp enough to form significant gaps. Intermediate studs may still be required to stabilize the slats against bending/warping, but may allow the slats to get much thinner than the thick slabs traditionally used

I do not currently have a sketch in digital form, but I can scratch one up if my explanation is unclear. Thanks again for your thoughts

TCB

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#33468 - 02/13/16 09:25 PM Re: Double-Wall Enclosure Concept [Re: TCB]
Hylandwoodcraft Offline
Member

Registered: 03/23/11
Posts: 141
Loc: Western NY
Hi TCB,
I'm sure you will find a lot of valuable knowledge on the forum, I know I have had a lot of food for thought!

As far as your question goes, it occurs to me that what you are proposing sounds a lot like a sort of timber framed Larsen truss. It seems like it would be much simpler to apply wall and roof trusses to your timber frame. It seems like the system that you are proposing would exponentially increase the time and complexity of timber framing a given building.

Are you sure that a plastered enclosure would be hard to upkeep in your area? I'm not sure on the area of Texas, but if it is the right climate it might be worth another look.

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#33470 - 02/13/16 11:57 PM Re: Double-Wall Enclosure Concept [Re: TCB]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 484
Loc: Vermont
Hi TCB,

I will do my best to run down your query and thoughts...

Quote:
...just haven't been able to get excited about the daub-styles which seem to require a lot of maintenance & are somewhat limited as far as their design flexibility...


Of all the infill methods (and there are hundreds if all timber framing cultures are taken into consideration) most are much more durable and insulative than many "think" or assume to be true. These still are a dominant form of enclosing timber frames and are still reasonably common in Europe and elsewhere as an efficient way to enclose and insulate a frame. More suited for less harsh climates of the temperate zones, they can still work in the colder regions as well with proper design...

Quote:
...So I looked into wood joinery-based systems, and found this diagram on a TFG thread...


The modality in the attached sketch/model is a common one in several cultures. Here in North America (there are...or where some examples in Louisiana) which are called "Piece sur Piece" and The other similar method is a "vertical planking system" often call Plank Frame Architecture ...Both represent a combination of timber framing and log or slab architecture...Depending on how and who facilitates this historical design, they can end up with a very functional and efficient structure...In some applications a "rendering" (aka plastering) may be necessary, yet in others and "all wood" system can be had as well...


Quote:
So I wanted to see if there may be a way to adapt it to a double-wall layout


There is...and probably too many to even begin to list... crazy Some better than others some more traditional than others..

"Wall Truss" systems (as Sean has referenced) are another (but different) modality. This is the system I recommend above all others for most Timber Frames unless following a specific "historic format" for a given reason or desire.

The commented advantages are many, such as the mechanical and wiring chases (aka "tunnels"), extra thick wall for little to no added cost, non bridging insulative modalities, deep window seating areas, improved storage capacity, et.

When I got to the disadvantages as described, I realised that you may be trying to create a "double walled" timber frame, which also exists, but is not as efficient in material utilization typically as a simple timber frame with a "wall truss" system. Since I tend to build almost exclusively on traditional stone foundations I can share also that a slab is not a necessity, even when using a double walled timber frame method, as even a stone plinth/socle system would support such a structures as would a simple "Raised Earth Foundation."

Hope that was of some assistance...

Regards,

j


Edited by Jay White Cloud (02/14/16 12:00 AM)
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#33473 - 02/14/16 12:13 PM Re: Double-Wall Enclosure Concept [Re: TCB]
TCB Offline
Member

Registered: 02/10/16
Posts: 26
Loc: Texas Hill Country
Hylandwoodcraft;
"As far as your question goes, it occurs to me that what you are proposing sounds a lot like a sort of timber framed Larsen truss. It seems like the system that you are proposing would exponentially increase the time and complexity of timber framing a given building. "
I actually got the idea for the frame-side of the concept by examining Larsen/Wall Truss builds. It seemed like they use an awful lot of vertical timber, though, almost approaching a sort of 'stick-construction' before sheathing is applied. My thought here was for the sheathing to be strong enough (and secure enough through joinery) that fewer vertical members would be needed to support it from the rear, while retaining most of the Wall Truss advantages. Think of a wall truss with several-foot gaps between the securing studs instead of 18" centers. Almost like building up a SIP between the main posts by constituent layers. The key to the framing portion is ensuring the two posts work together as a unit (which may prove trickier than I hope)

As far as complexity, it's a non-issue on this design for the time being (it's admittedly a bit of a science experiment I have several years to figure out, before deciding if it's worth it or not to preserve certain design elements). I'm also hoping the octagonal floorplan will allow for eight largely-identical "wall bents" to be fabbed up prior to raising, which would allow for a bit more subassembly complexity without being so annoying. The way it works (in my head) is that an assembled frame bent would have a second set of posts stacked onto the first before being raised. If the planks can be flexible enough to be bowed into place after raising, construction could potentially be very easy.

Jay White cloud;
"Of all the infill methods (and there are hundreds if all timber framing cultures are taken into consideration) most are much more durable and insulative than many "think" or assume to be true. These still are a dominant form of enclosing timber frames and are still reasonably common in Europe and elsewhere as an efficient way to enclose and insulate a frame. More suited for less harsh climates of the temperate zones, they can still work in the colder regions as well with proper design.."
I am certain Adobe can probably work out here with a generous overhang, and may even be quite viable to make with the limey caliche soil (basically crushed/compacted coral), but it simply isn't seen, nor was it historically common from what I can tell. Go much further west where it is much drier and it's common, though. Not sure if it's the high humidity swings (20-100), or the high temperature swings (0-120), or the character of the soil, but my worry is anything just moves around too much to avoid cracking & frequent repair. Heck, the worst part of the drought was wrecking full-on slab foundations, soil cracks being plumbed at over 10ft deep in more clay-ey areas!

Mostly though, I simply have no experience with it at all, and am uncomfortable embracing something so different from what I expect a 'wall' to look/work like. Historically, folks primarily had wood to work with (think Old Timey Hollywood western town construction), and before that frequently used cut/natural stone & mortar when they needed something more durable. Natives seemed to prefer caves, when available, or portable structures so they could follow the water. Lot of brick and limestone block, once railroads brought these products out, even to this day*.

"The modality in the attached sketch/model is a common one in several cultures."
That should mean it's as good an idea as pita bread & tortillas then, right? smile

"In some applications a "rendering" (aka plastering) may be necessary, yet in others and "all wood" system can be had as well..."
I figured plastering was feasible if that finish was desired; this plank scheme is somewhat like Wattle & Daub on steroids, after all. Not even drywall survives the weather swings more than a year out here without diligent climate control and high quality construction (peeling tape & warping is common in garage interiors), so plaster has its work cut out for it, even if it is slightly more flexible.

"There is...and probably too many to even begin to list... crazy Some better than others some more traditional than others.."
Interesting. Like I said, the forum I was reading through was trying to find ways to effect a double wall post/plank system, and it seemed like there wasn't much to draw from that they could find. Glad to hear it isn't such a wild idea, after all.

"When I got to the disadvantages as described, I realised that you may be trying to create a "double walled" timber frame, which also exists, but is not as efficient in material utilization typically as a simple timber frame with a "wall truss" system"
Yup, pretty much a double frame supporting a double-roof; but a stripped down one using slightly smaller timbers & wide-spaced intermediate posts. My goal is to see if the planks+support posts can rival or exceed the timber efficiency of a wall truss by halving (or more) the frequency of vertical elements supporting the infill. Admittedly, the whole purpose for the double frames was to create an airgap for better insulation, as opposed to simply making the posts thick enough for two parallel plank slots (or covering them up on one side with a wall truss)

"Since I tend to build almost exclusively on traditional stone foundations I can share also that a slab is not a necessity, even when using a double walled timber frame method"
Hill Country caliche isn't quite as bad as Blackland Prairie soil, but I think ground moisture (cycling from bone-dry to saturated several times a year) hydraulically moving things is why pier-based foundations have fallen from favor. Older pier structures have almost universal foundation problems (lots of foundation repair companies all over). They can certainly be done as the bedrock is usually less than 10ft down (or like 5ft in the Hill Country) but require more work drilling through rocky or gummy soil. Whenever someone gets a pool installed, the contractor has to bring in a massive 'rock chain saw' trencher to get anywhere!

Part of the issue is my present desire is to build into a hillside, which (needlessly) complicates things a bit, in ways our ancestors wouldn't have bothered with, but which I'd still like to explore as an option.

*Pretty much all the high-cost educational or government buildings getting designed by architects are using what I affectionately call "Jet-Stones" aesthetics; lots of limestone, lots of glass/aluminum, and arranged into rather futurist angular forms. Sort of a combination of the Flintstones and the Jetsons.
New Construction at A&M

TCB

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#33475 - 02/14/16 12:38 PM Re: Double-Wall Enclosure Concept [Re: TCB]
TCB Offline
Member

Registered: 02/10/16
Posts: 26
Loc: Texas Hill Country
Hopefully this helps, somewhat. Planks set into grooves in the two sets of posts, the M&T cross ties between them, the waist-height 'sil' closing out the main portion of the wall with loose insulation*, and the removable vertical planks down at the bottom on the interior covering a plumbing path that can be insulated with foam block as needed (a tacked-down trim strip would secure their lower ends against the floor). One additional benefit I realized mocking it up, is the interior look is likely attractive enough to avoid any additional effort beyond a canned finish (not even that, if engineered wood flooring is used to form the interior planks; only the exterior ones need to be somewhat strong)

*the sil board would be a convenient place to attach window boxes, being joined into the posts at its corners


This is mocked up with 12" thick wall, and a 4ft post span, each post a 4x8. Seems like it could go wider with a properly-designed roof & floor truss system, comparing it to other 8X8 post designs I've seen (especially if the two layers of planks are intermittently buttressed by stick-lumber studs). I hope it's obvious the sizing/spacing of all these elements are entirely improvised; all will be changed when I get to the calculations phase of design.

Also a very rough depiction of how the double-roof sits on the two posts (minus the ties connecting them). As you can see, there is a continuous gap of several inches between the wall and roof layers from top to bottom, even with major rafters jutting out to support a large overhang (and possibly even a vented roof layer). I think the primary practical difference with the Larsen-style truss is that the second layer of wall is not 'hanging' cantilevered off the foundation on the primary posts. No idea if this is advantageous or not, however. It also does not rely on fasteners smile


Edited by TCB (02/14/16 12:42 PM)

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#33476 - 02/14/16 12:44 PM Re: Double-Wall Enclosure Concept [Re: TCB]
TCB Offline
Member

Registered: 02/10/16
Posts: 26
Loc: Texas Hill Country
Please let me know if you are bothered by the large posts (bad habit of mine ;)). Technical discussions like these are always a bit 'fractal,' with each response generating two more lines of thought.

TCB

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#33493 - 02/15/16 12:26 PM Re: Double-Wall Enclosure Concept [Re: TCB]
D L Bahler Offline

Member

Registered: 05/17/10
Posts: 946
Loc: Indiana
I think you could eliminate the double-framed roof as you show it here entirely, and accomplish essentially the same thing by having a 'double roof' as I often have seen it employed in Switzerland. You have your primary roof onto which an insulation barrier is applied. Atop that, you attach strapping screwed through the insulation which holds the roof decking or tiles or whatever you apply.

This same concept is used somewhat less often in North America.

I'll fill you in also on how this system is used today.

First of all, 'Plank and frame' or 'Bohlenwand' techniques are the inferior of the two solid wood infill techniques. The better technique is what I know as 'Fleckwand' which you should think of as a log infill. This technique descends from a hybridization of log and timber building in the sub-alpine regions on the northern verge of the Alps (in contrast to the Bohlenwand or thin plank infill which is simply a timber frame with boards inserted between the framing)

A lot of the Log infill methods actually are not infill at all, the horizontal timbers are bearing the loads and the posts simply secure their ends and create a simpler means of laying out and joining the corners. So it is really a log structure with uprights (not posts, because they don't carry any weight) Though later it evolved into timber frames with log infill.

What some manufacturers are doing today is constructing the log infill as an engineered component, a piece of insulating foam sandwiched between two layers of wood. (I am not a fan of this)

These houses have modest thermal performance without adding any insulation. Even today new houses are sometimes built with heavy log infill and no insulation added. However, when they do wish to add insulation it is applied to the inside. Americans like to have big heavy timbers seen inside the house and a nice wrap around the inside. The people along the northern edges of the Alps prefer to leave the framing exposed on the outside and apply a nice enclosure on the inside. They use generous overhangs (think like 12 feet) to keep the frame dry.

The Swiss sometimes employ a concept quite similar to what you seem to be working toward, only instead of building 2 separate heavy timber frames they construct a light frame on the inside. They don't use this frame to support anything -the loadbearing structure is all tied into the exterior frame.
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#33506 - 02/15/16 07:54 PM Re: Double-Wall Enclosure Concept [Re: TCB]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 484
Loc: Vermont
Hello TCB,

Never worry about length... wink....You have to ask what you are thinking about, and sometimes it can get long...

Originally Posted By: TCB
.../am uncomfortable embracing something so different from what I expect a 'wall' to look/work like..


I can appreciate that for sure...Yet you have explained and shared, "...I simply have no experience..." and as such perhaps should really push past your comfort zones (with current understanding) so no option of consideration is left out...???

Just a suggestion of capacity in scope of comparative understanding. This is one of the reasons folks do hire Architects/Designers and the collective knowledge (and team) they bring with them...

Continued....
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#33507 - 02/15/16 07:58 PM Re: Double-Wall Enclosure Concept [Re: D L Bahler]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 484
Loc: Vermont
Hello TCB,

Never worry about length... wink....You have to ask what you are thinking about, and sometimes it can get long...

Originally Posted By: TCB
.../am uncomfortable embracing something so different from what I expect a 'wall' to look/work like..


I can appreciate that for sure...Yet you have explained and shared, "...I simply have no experience..." and as such perhaps should really push past your comfort zones (with current understanding) so no option of consideration is left out...???

Just a suggestion of capacity in scope of comparative understanding. This is one of the reasons folks do hire Architects/Designers and the collective knowledge (and team) they bring with them...



Originally Posted By: TCB
Historically, folks primarily had wood to work with (think Old Timey Hollywood western town construction), and before that frequently used cut/natural stone & mortar when they needed something more durable.


Wood was employed, of that there is no doubt. I would share, historically the "Hill Country" of Texas was dominated mainly by an equal blend of timber/log, adobe brick, and hand-cut limestone with a very Germanic influence in architectural forms strongly influence as well by the Mestizo modalities of construction.

Originally Posted By: TCB
...this plank scheme is somewhat like Wattle & Daub on steroids, after all...Not even drywall survives the weather swings...


"Plank" infill methods does have some limited characteristics to "wattle and daub," but it is limited. Either is applicable as "drywall" has no comparison in this conversation.

Even a "light daub" system of say a "Bousillage" type would be far more robust than any modern "drywalls," and if you combine this with adobe methods of the region, (along with the appropriate lime plasters) you have an extremely durable system plastering (inside) and rendering (outside) finishes.

None of this is to say a "plank wall" isn't great! I like both equally in many ways... smile

Originally Posted By: TCB
Older pier structures have almost universal foundation problems (lots of foundation repair companies all over).


Foundations in general, in historic architecture, can often present as having more issues than they actually have, and/or suffer from neglect and inappropriate modifications by "ill experienced" over the decades or even centries.

"Hill Country caliche" and the subsequent surface to shallow bedrock formations of this region actually lend themselves nicely to either "raise earth/gravel foundations" and/or "plinth and post" foundations alike. Both have historic precedent and a fair amount of Library of Congress (et al) documents and blueprints exist for study and review.

Continued...
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#33508 - 02/15/16 07:58 PM Re: Double-Wall Enclosure Concept [Re: D L Bahler]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 484
Loc: Vermont
Originally Posted By: TCB
Part of the issue is my present desire is to build into a hillside, which (needlessly) complicates things a bit, in ways our ancestors wouldn't have bothered with, but which I'd still like to explore as an option.


Of all the "indigenous" forms of architecture that may be found in this region, "fossorial forms" are perhaps very german if well situated in a given landscape. Grant you the indigenous cultures took full advantage of natural weaknesses in the topography rather than "digging in" yet the later was done and some other augmentations as well

All in all, I think a "dug in" form of architecture (in the correct setting) would serve you well..IF...well designed and facilitated. I am not a fan of "below grade living spaces" in most regions and by most designs...yet would also offer and validate that when done well, and with vernacular and natural systems, can be one of the most enduring forms of architecture available...

Continued...
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#33509 - 02/15/16 07:58 PM Re: Double-Wall Enclosure Concept [Re: D L Bahler]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 484
Loc: Vermont
Originally Posted By: TCB
...Planks set into grooves in the two sets of posts...M&T cross ties...waist-height 'sil'...with loose insulation*...removable vertical plank...plumbing path...foam block...engineered wood flooring is used to form the interior planks...12" thick wall...4ft post span, each post a 4x8...double-roof...support a large overhang (and possibly even a vented roof layer)...


All in all, I love the concept, and it is actually following a design parameter that several Timberwrights (myself included) are starting to explore and/or employ in their designs. Much of it is nothing new and more a "dusting off" of some older vernacular methods from around the globe.

I love "Double Roofs" and can not expand enough on how functional and aesthetically pleasing they are. That was a wonderful choice...

As for insulation, I no longer use "blow ins" as they are to plagued with long term issues and/or do not function as claimed. I prefer and use either natural insulative materials, mass systems like log, plank, stone, cobb, light cobb, adobe, etc. For a "modern insulation" (yet over 150 years in use with excellent results) I employ mineral wool batt and board.

Your design is very much like a "Wall Truss" however I would say more than half of these contemporary wall systems seldom are "hung walls" (though this works well if designed well) and actually rest on foundation of some form...

Wall trusses and your modified timber form of them both lend themselves well to "cold roof" and "rainscreen" modalities as well...

I look forward to watching you develop your concepts.
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#33529 - 02/16/16 10:38 PM Re: Double-Wall Enclosure Concept [Re: TCB]
TCB Offline
Member

Registered: 02/10/16
Posts: 26
Loc: Texas Hill Country
Thank you both for your thoughts!

D L Bahler;
"First of all, 'Plank and frame' or 'Bohlenwand' techniques are the inferior of the two solid wood infill techniques. The better technique is what I know as 'Fleckwand' which you should think of as a log infill. This technique descends from a hybridization of log and timber building in the sub-alpine regions on the northern verge of the Alps (in contrast to the Bohlenwand or thin plank infill which is simply a timber frame with boards inserted between the framing)"
I can see how this would trend toward a convenient way to stack heavier timbers/logs, but I'm not certain such heavyweight construction would work for me; for a two-story structure far, far away from large-diameter lumber supplies. My plan of attack was actually to see if I could get the exterior layer to be built of staggered Hardieplank (or similar) and the interior of engineered flooring; I'm not sure how realistic these are given the spans they'd be bridging between frames, but the concept of puzzle-piece interior/exterior layers with minimal follow-on finish work is appealing to me.

It's funny you mention the Swiss & large overhangs, since it appears I am rapidly trending toward that sort of design, here. I think I may actually adopt the two-frame solution you described, since as a two-story structure it is somewhat convenient; support the roof on the outer level with a beefy frame and a lightweight interior frame supporting that face of the wall & partitions, but a heavier interior frame on the lower story to carry the floor joists as well as to stabilize the exterior frame structure.

Jay White Cloud
"Even a "light daub" system of say a "Bousillage" type would be far more robust than any modern "drywalls," and if you combine this with adobe methods of the region, (along with the appropriate lime plasters) you have an extremely durable system plastering (inside) and rendering (outside) finishes."
Very interesting. I'd always thought that plaster fell by the wayside for being crack-prone as well as labor-intensive, but perhaps only the latter? Whichever is less hassle to keep up with is my preference (and I wouldn't mind learning to plaster, at least on the room-interior walls & ceilings where it would likely be). At any rate, I'll be focusing on surface finishes more once I get further along.

"I love "Double Roofs" and can not expand enough on how functional and aesthetically pleasing they are. That was a wonderful choice..."
You may think twice about that once I get it fleshed out in the other thread a bit more. Or rather, I may think twice once the time comes to actually start figuring out how to make & assemble everything, lol.

"Foundations in general, in historic architecture, can often present as having more issues than they actually have, and/or suffer from neglect and inappropriate modifications by "ill experienced" over the decades or even centries."
Fair enough; I'm sure a good number of the vintage structures themselves suffer from inappropriate construction methods in the first place, that a properly trained professional now readily-available would be able to avoid. I still like the idea of a concrete 'bathtub' for building partially into a hill, even knowing concrete isn't all that waterproof. I'll be sure to open a thread on the topic once I have more details to discuss.

"For a "modern insulation" (yet over 150 years in use with excellent results) I employ mineral wool batt and board."
I agree the blown stuff is kind of a pain, especially when you actually have to work with it yourself instead of paying 'some other guy' to deal with it. Honestly, it may not even be that good an idea given the lack of positive seals between the posts and the planks; could be leaky. I won't be purposely seeking out sustainable solutions unless they are the best fit for my situation, but I think you're right that a quilted/batt type material --whatever it's made of-- would work a whole lot better than a loose one, and probably be easier to install. Less mess if I have to dig in there to route whatever new utility line is a 'must have' ten years from now, also (this serviceability aspect is part of the reason I am opposed to a solid infill wall system; not sure how one goes about retrofitting a conduit line through a block of cobb or wattle/daub without a whole lot of work)

"Your design is very much like a "Wall Truss" however I would say more than half of these contemporary wall systems seldom are "hung walls" (though this works well if designed well) and actually rest on foundation of some form..."
Interesting, the Larsen-type ones I saw all seemed to be suspended, and I assumed it was to shield the foundation from rain or to ensure ventilation of the more exposed wall frames. Perhaps I can get away with just my overhangs protecting me, here. I've actually been trying to figure out what the best plan is for the floorplate side of these plank walls; I assume you don't want to just have them sitting in a sunken groove in a plate that is some combination of rot-prone or ugly, but a neat trim-based solution isn't jumping to mind readily. Lot of examples in pictures just seem to have boards sitting on the foundation directly, or suspended on sacrificial spacers (presumably some sort of filler material seals the gap internally). Is that really all there is to it? I expected more complexity from the Swiss, lol.

"Wall trusses and your modified timber form of them both lend themselves well to "cold roof" and "rainscreen" modalities as well..."
I've read about cold roofs, but 'rainscreen' is a new term; could you explain? I decided to run with the double-roof once I realized that I could get a thick, insulated roof over the interior areas, but a pretty thin overhanging roof over the outside (to keep the externally-visible roof profile looking thin). One of those design choices that just seems perfect the second you visualize it.

TCB

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#33530 - 02/16/16 10:49 PM Re: Double-Wall Enclosure Concept [Re: TCB]
D L Bahler Offline

Member

Registered: 05/17/10
Posts: 946
Loc: Indiana
TCB,

I think maybe a good fit for the sort of scenario you are looking at would be an industrial revolution era German and Swiss (My research suggests it may have originated in either Bern or Basel, or just across the Rhein is south Germany) sort of light timber framing. For good pictures, go to google.ch (swiss google) and search the term 'Riegelbau' then look up images (it should default to English, but if it doesn't 'Bilder' is the German word for pictures). This is the sort of framing that's most common at least in the Swiss Canton of Bern today, an extraordinarily efficient building system.

I think you could easily adapt this to work with your system without creating tremendous waste and redundancy. Basically two such light frames built together.

Actually you have really got my mind working, and possibly led me to just the answer I have been looking for to build a timber framing system that is super efficient, yet can still incorporate the sorts of features people want to see. I'll have to open up sketchup and play around with some things...
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#33532 - 02/16/16 11:25 PM Re: Double-Wall Enclosure Concept [Re: TCB]
TCB Offline
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Registered: 02/10/16
Posts: 26
Loc: Texas Hill Country
"framing system that is super efficient"
Aerospace engineers are really bad about that, actually. Hopefully this concept, unlike aerospace stuff, can actually be built without five mortgages! The types of design goals you mentioned are exactly what I'm going for, so I'm not surprised we're on a wavelength.

Thanks for the tip on 'Riegelbau,' very good stuff there aesthetically as well as structurally, to draw from. Not super sure how to adapt it to an octagonal plan with shallow roof, but I'd like to try. Only thing I don't like is the number of hammer-beam roof gables I keep seeing; they look...difficult.

I also don't know what it is about Bern; this is like the fourth or fifth product from that specific region I've come to admire greatly, despite not having a particular fascination or connection to the place. I should really visit some time, since the place seems to just exude excellence (beer, housing, guns, hand tools, machine tools, the list goes on...)

TCB

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#33533 - 02/16/16 11:41 PM Re: Double-Wall Enclosure Concept [Re: TCB]
D L Bahler Offline

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Registered: 05/17/10
Posts: 946
Loc: Indiana
I've seen it done, regarding the octagonal plan.

And roofs can be done any way you want, the concept of this framing is that the framing of the roof and the walls are pretty much independent of each other.

And I'm a product of Bern, so I tend to be biased to the region smile All those things you mention, ya they're kind of a big deal there! You buy me a plane ticket, I'll give you a personal tour! I know all the best spots...

As for framing octagonal designs, it's actually done quite frequently (think castles) Usually, they accomplish this by having a post in the corner that is cut with specially angled faces. But I rather like the idea you show in your other thread of just putting one post either side of the corner and letting the trim job do the rest (though this may be hard if you're doing an infill)

I'll look through my extensive photo gallery (think like 5k pictures) to see if I can find you some octagons.

But regarding super efficient, ya I'm swiss so... I tend to be preoccupied with the concept in a way that is probably annoying to everyone else (why can't you just let things be -because I'm Swiss, dangit!)
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#33534 - 02/16/16 11:48 PM Re: Double-Wall Enclosure Concept [Re: TCB]
D L Bahler Offline

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Registered: 05/17/10
Posts: 946
Loc: Indiana
By the way, I should mention Riegelbau is analogous to the German Fachwerk, which is what most Americans at all familiar with the style of framing would think to use. I use Reigelbau because it's more specific -Fachwerk includes a number of different framing styles and really refers to the fact that a building is half timbered. Riegelbau is a very specific type of framing that bears this name whether it is used for a half-timbered structure, or whether the frame is wrapped.

This is the sort of framing most commonly used in Switzerland today, and interestingly enough is frequently employed in the mountainous regions and given a facade to imitate the log building styles native to the region. (A close examination will usually reveal the counterfeit)

There's my off the topic rant for the day...


Also regarding the heavy timber infill, I wasn't inserting that there in an attempt to persuade you to the idea necessarily, just more as an effort to put things in perspective and shed light on how the techniques are being used right now.
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#33559 - 02/24/16 07:54 PM Re: Double-Wall Enclosure Concept [Re: TCB]
TCB Offline
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Registered: 02/10/16
Posts: 26
Loc: Texas Hill Country
"As for framing octagonal designs, it's actually done quite frequently (think castles) Usually, they accomplish this by having a post in the corner that is cut with specially angled faces. But I rather like the idea you show in your other thread of just putting one post either side of the corner and letting the trim job do the rest (though this may be hard if you're doing an infill)"
I had kind of figured on placing a T&G 1x12 vertical board on either side of the corners as a sort of sheathing for the closeout. Done cleanly, would even look like larger timber$ smile

Also had a question relating to these corner joints; I had originally planned on the standard practice of running 'lintel' boards (top plate/etc) between the posts over each wall and scarf/lapping them over each other at the corners instead of over a post as is typical. However, I am trying to find a place for my floor joists & inner roof members to sit, ideally also at the post locations. With smaller timbers, is it wise to have two orthogonal members coming into the post at roughly the same elevation, or will the post be too weakened to properly support the upper floor walls?

I had the idea to rest the plate timbers across the uppermost 'cross ties' (appears to also be called 'nogging' if I understand correctly) connecting the inner/outer posts. To me, this seems entirely reasonable provided the ties are sufficiently large since the span is only several inches and the only loads/joints from the other structural members are at the posts, but perhaps building codes disagree? This would have the benefit of also leaving the tops of the plank-grooves in the timbers exposed for installation after the superstructure is installed, rather than during, as well as of course leaving a whole lot more cross-section at the upper portion of the post. Also very simple to cut notches in the top plates at each supporting board to tie the posts across the wall spans securely.

Since the M&T cross ties/nogging pieces will have to sit well below the very ends of the posts, my next thought was the remaining post length extending above could be narrowed to a tennon that runs through the center of the floor joist resting on top of the top plate (between the inner/outer posts) up into the next post above. This would neatly tie the two stories' posts to each other as a sort of splice, while at the same time clamping the floor joist timbers between them onto the top plate. It also makes it easy to run the floor joists clear past the exterior wall to form the structure for the perimeter outdoor walkway I seek.

And on that note; if the cantilever of the floor beams past the wall are great enough to necessitate a cross brace down to the post, is it a good idea to have it coincident with the nogging ties between the post pairs, or is intersecting more than two timbers at a given joint location generally a poor idea? That's kind of been my guiding principle so far, since it makes the joint design a lot easier smile. Putting the thrust of the brace in line with the cross ties would seem to best support the posts against bending, though.



TCB


Edited by TCB (02/24/16 07:55 PM)

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#33567 - 03/02/16 07:24 PM Re: Double-Wall Enclosure Concept [Re: TCB]
TCB Offline
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Registered: 02/10/16
Posts: 26
Loc: Texas Hill Country
Man, things got really dead around here. I assume winter's breaking and folks are getting back to work? Much better things to do than tool around on a forum, to be sure smile

I've decided to 'start over' on my design file structure --that aforementioned order of operations thing with regards to architectural design was kicking my butt. Turns out you need a real strategy for organizing the hundreds (thousands?) of parts & assemblies that go into a structure if you want to make heads and tails of it as you go along wink. Hopefully I've learned enough from this that I won't have to reboot it a second time. So, I'm recreating most of the same geometry, but broken down into floor level, then wall direction (N/S/E/W/etc). I think it's possible to do the walls as near pre-fab, with each face a complete frame 'bent' so to speak, and this file structure should help coordinate that.

I did have (yet another) question about a framing technique I am thinking of using. If double-roofs are such a great/practical solution, why not a structural double-floor? Floor joists seem to be among the wider (taller) timbers used in a lot of designs in order to get the rigidity us humans desire, but couldn't two layers of vertically-tied smaller members function as a truss & do a better job overall (lighter, stiffer, upper/lower joints could be optimized for tension/bearing loads, easier routing, better insulation/soundproofing)? Might squeak more when walked on, I dunno...

TCB

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#33568 - 03/02/16 07:28 PM Re: Double-Wall Enclosure Concept [Re: TCB]
Jay White Cloud Offline
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Registered: 11/06/08
Posts: 484
Loc: Vermont
Hi TCB,

I am not sure a double floor (other than in some applications to high plumbing) is as warranted as a double roof. Double roofs have a very long and well established logic and practice in historical application...

As for "floor truss" systems, yes those have merit in some areas and application...though not typical for most domestic timber frame needs/requirements of load...

Regards,

j
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#33569 - 03/03/16 02:56 PM Re: Double-Wall Enclosure Concept [Re: TCB]
D L Bahler Offline

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Registered: 05/17/10
Posts: 946
Loc: Indiana
TCB,

I've been meaning to respond but I've been very busy.

I'll give a quick run-down of my thoughts.

My first observation is, why worry about making the inner framework in your walls structural? This seems to me to be creating a lot of unnecessary joinery without a whole lot of benefit to the structure. My approach would be simply to make an inner curtain wall and let the outer wall do everything structurally.

With this approach, you could just build an outer wall system of any sort you wish. I'd use a 'Riegelbau' style frame, because I think it's well suited to this application, but I'm also biased. The inner wall then serves only as a means of containing the insulation and providing an attractive interior surface.

Off hand I don't see any great problems with your scheme, other than that it may result in more difficult joinery than you may wish to do. I am attracted to systems that simplify the joinery as much as possible, so judge my remarks in light of that not as abject criticism of your ideas.

Regarding double floors,

You are right that such a system could be more efficient from a materials standpoint. However, I would guess it's a lot more work to do and far less efficient from a labor standpoint. You will just have to choose which of these is more important in your situation.
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#33589 - 03/08/16 11:33 AM Re: Double-Wall Enclosure Concept [Re: Jay White Cloud]
TCB Offline
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Registered: 02/10/16
Posts: 26
Loc: Texas Hill Country
"As for "floor truss" systems, yes those have merit in some areas and application...though not typical for most domestic timber frame needs/requirements of load..."
Since I have a 'round' floorplan, and at present do not intend on having strategically-placed lower walls (just two columns near the center) I thought it might be desirous for strength reasons --granted I still need to run the numbers, but the 15-20ft span seemed a bit large unless giant joists are used, if I am to have a rigid floor surface. It is interesting that dual floors/truss floors aren't more common, though, since they do much of the same types of jobs as a roof.

TCB

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#33590 - 03/08/16 11:49 AM Re: Double-Wall Enclosure Concept [Re: D L Bahler]
TCB Offline
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Registered: 02/10/16
Posts: 26
Loc: Texas Hill Country
"I've been meaning to respond but I've been very busy."
Same here, I figure it's just that time of the year (I was getting a bit worried that there had only been like three posts across the entire site for about a week, though :))

"My first observation is, why worry about making the inner framework in your walls structural? This seems to me to be creating a lot of unnecessary joinery without a whole lot of benefit to the structure. My approach would be simply to make an inner curtain wall and let the outer wall do everything structurally."
When I went to look at designs for floor/wall/second floor joint layouts (each post spans only a single story to keep costs down), it struck me that the column assembly is significantly weakened by the presence of the cuts for the floor joists, as well as their off-axis loading. By splitting the column into two layers, the inner layer can be carved up to support the floor joists, leaving a simpler and more uniform outer spliced column element. Since the structure is only two floors, the second layer of (more weakly jointed) interior posts would support the less structural internal roof rafters, while the outer column would bear the brunt of the roof loading and deliver it straight down (stabilized by cross ties with the interior layer).

Basically, it seemed like a convenient way to split up the loads applied to vertical support posts in order to simplify the engineering side of things, if not assembly/construction. Since I plan on having a generous walkway cantilevered on the exterior opposite the interior floor joists (i.e. joists on both sides of the wall in some form) it may not be worth the trouble. I do still like the idea of no more than two or three timbers intersecting at any point, though.

If I can find a diagram of a wall joint layout where;
-Two columns are stacked/tied together along Z
-Two floor plates tie in along Y
-Two floor joists tie in along X
pretty much like an interior frame junction, only the result doesn't remove so much material from the members that another row of supports (i.e. an exterior wall frame) are not required to stabilize. Rather demanding task, I know.

"You are right that such a system could be more efficient from a materials standpoint. However, I would guess it's a lot more work to do and far less efficient from a labor standpoint."
I agree completely, and if it is not needed (see above comment about the spans involved) I'd just as soon not go this route. However, the complexity, I hope, is less of an issue than it might be, since my floor plan is basically a lofted arrangement, with only half the upper floor, floored (the remaining half of the octagon is an open cavity). So if it's twice the trouble, it's still only half the square footage. Or something.

TCB

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#33592 - 03/10/16 10:29 PM Re: Double-Wall Enclosure Concept [Re: TCB]
TCB Offline
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Registered: 02/10/16
Posts: 26
Loc: Texas Hill Country
Another question I had, about the Riegelbau framing concept; is there any particular rule about exactly where the inclined timbers should fall in a given wall/bent (center, edges), or which direction (inclined toward center, or toward ends)? It seems mostly important that they be balanced/braced against each other on each face of the building, but are there any off-axis loading considerations I should be careful of?

TCB

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#33594 - 03/16/16 07:06 PM Re: Double-Wall Enclosure Concept [Re: TCB]
D L Bahler Offline

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Registered: 05/17/10
Posts: 946
Loc: Indiana
Regarding bracing,

The only 'Rule' is that braces be balanced, as in each brace leaning in one direction be counteracted by one leaning in the opposite direction.

Some people apply rules about there being a brace every X amount of meters, things like that, but there is no hard set universal rule about this.

Most 'rules' about bracing are regional characteristics and local architectural preference more than anything else. Some regions, for example, like to place the braces in the first cavity in from a corner or wall junction. Some like to put them in the second cavity. Some like to first lay out where all the windows and doors will be, and then put the braces wherever they will fit.
Sometimes braces are completely absent from exterior walls due to windows and doors taking up too much space, and the structure is stabilized by bracing in the interior walls and the stiffness of all the cross timbers involved in framing windows.
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#33596 - 03/17/16 01:09 AM Re: Double-Wall Enclosure Concept [Re: TCB]
Jay White Cloud Offline
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Registered: 11/06/08
Posts: 484
Loc: Vermont
If following strict a Riegelbau framing modalities, or other historic formats, then each region (as David has suggested) has its individual predilections. If being fully historically accurate, then one could follow the given regional modality as a guide.

Originally Posted By: TCB
It seems mostly important that they be balanced/braced against each other on each face of the building, but are there any off-axis loading considerations I should be careful of?


Yes..."compression resistance" in "oblique bracing" works better in a balanced format. Further, "Oblique Bracing" tends to "work" more effectively when larger in size of the triangle it forms, there by not acting as a fulcrum against the corresponding joinery. Also, "oblique bracing" modalities also function better in the "buttressing context" (i.e. at the base of a post) and can also work very well in the "horizontal" configuration within floor and roof systems as well. (i.e. "strong back" and "dragon beam" systems)

If this structures is not an example of historic replication, then "bracing" can take on many different formats that may be not only applicable but more easy to facilitate.

"Bracing" does not have to be "oblique" in nature to be functional and/or enduring. I seldom use "oblique bracing" systems in structures I design or facilitate. Asian (and some European) modalities also rely heavily on "horizontal bracing systems" and/or "infill systems" to give the structure the requisite "resistance" against racking that it needs to be enduring...Horizontal systems typically are less difficult to facilitate/build. Additionally, horizontal systems of bracing tend to never interfere with fenestrations, ingress/egress logistics within the frame and other consideration that oblique bracing can often obstruct and incomber.
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#33597 - 03/17/16 02:50 PM Re: Double-Wall Enclosure Concept [Re: TCB]
D L Bahler Offline

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Posts: 946
Loc: Indiana
Jay, the system we are discussing in regards to Riegelbau is not oblique or triangular bracing. It is s different concept that functions on different (although related) principles

The theory behind the long slanted bracing in German building styles is that a brace to a post compromises its integrity, so the braces here join to the sill and the top plate. This results in a lack of any triangles, so rather than relying on the immutability of the angles of a triangle to maintain squareness of the walls, we are relying on the fact that the brace has to stand upright for the walls to shift.

This is why we have to balance braces in this system: A brace slanting one direction has to stand upright for the walls to shift against its lean. The weight of the structure alone is enough to prevent it. In contrast, the brace simply has to fall over to shift the walls in the other direction, which the brace itself is actually actively encouraging to a small degree.

Contrast this to standard oblique bracing, where we balance bracing due to the nature of the joinery: a standard mortise and tenon only works under compression, so the brace is only effective in one direction. Contrast this further to older styles of oblique bracing using dovetail joints, which don't have to be balanced because the joint works well in either direction. (In most cases in southern Germany and Switzerland, slanted uprights directly replaced dovetail oblique bracing, without ever seeing the use of mortise and tenon oblique bracing like we are accustomed to in the US)

Setting history aside, and going strictly toward practicality I recommend using the large agricultural buildings of the central part of the Swiss Plateau as a good model to follow (since this is pretty much what they are designed to be: pure practicality without any fancy and unnecessary architectural elements like you might see in old cities or most of Germany)

Standard oblique bracing (triangles) can be scaled up to a point, once you get too large then they begin to act as levers and pry the posts out of their sockets. I suspect it is this fact that led to the invention of the Riegelbau style of oblique bracing, as carpenters realized that longer braces are more effective (study Swiss roof framing, where enormously long braces are frequently used) but have inherent issues in certain scenarios. (The English and French appear to have arrived at a different solution to this problem, tying their extra long oblique braces across multiple posts to negate the prying effect)

There is no strict Riegelbau framing tradition. Riegelbau is a general classification that includes a great deal of closely related framing styles. The only necessary element to classify something as Reigelbau is that a light framing method with an interruption between stories is used (thus the 'Riegel' or 'Rail') How the stories are joined together, how the structure is braced, etc. are all flexible. 'Riegelbau' is only slightly more specific than 'North American Timber Framing'


Edited by D L Bahler (03/17/16 02:53 PM)
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#33598 - 03/17/16 07:26 PM Re: Double-Wall Enclosure Concept [Re: D L Bahler]
Jay White Cloud Offline
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Registered: 11/06/08
Posts: 484
Loc: Vermont
hi David,

I don't want to get too far away from TCB's queries and topic line of his "concepts" of a double wall system... I will cover some points of clarification then leave it be for TCB continued questions...


Originally Posted By: D L Bahler
...the system we are discussing in regards to Riegelbau is not oblique or triangular bracing...


Actually it very much is in the "oblique bracing" category of systems. Agreed it is perhaps one of the best, oldest and most functional of these systems, however any time there is the formation of a "canted system" that does most of its work..."in compressive"...loading, then it is considered and "oblique system" from an engineering viewpoint, no matter how slight the angulation may be or the relative size of the bracing modality itself.


Even the the broad range of "Riegelbau" bracing systems are variable...they are "slanted" and do work in a compressive loading condition for most of their work in the architecture. They do this marvelously because of their larger size, and "sill to plate" formating. They still are in the "oblique system" as they are a...

Originally Posted By: D L Bahler
...long slanted bracing...building styles...braces here join to the sill and the top plate....


And this does indeed...from an engineering perspective (having discussed this numerous time with my own PE I work with)... form a "triangulated system" of compressive resistance, which is the primary function of most of the working systems within the "oblique bracing" modalities...Again, this is one of the best because of the large "slanted" (aka bracing) format, its "buttressing effect" and "sill to plate orientation."

I would further add in support that, indeed the older styles (and larger) "oblique bracing" systems did have some limited work capacity in "tension" bearing capacity. This does not change the primary "work force" of these systems to do most of there function in a "compression resisting" format, as "let in" bracing..."strengthening"...in the tension format was not the primary function, nor has this been bore out in any of the historic research of merit that studies these vintage systems and the application to the architecture...

I more than agree that most contemporary or "standard oblique bracing" primarily "only works under compression" and offers virtually no "tension effect" within the frame...I would have to challenge that the "dovetail joints" of any of the let in systems "works well in either direction." Some yes...but this system is still primarily a compressive system not a tensioning one, though agreed it offers a limited capacity in that regard much more so than the shorter "stub tenon" methods of a standard brace system we find today...as these "stub tenon" oblique bracing systems historically in some region do not even have pegs at all..Some are simply "well fitted" and/or "wedged in place" after raising further facilitating "tightening" at a later date by more pressure added to the wedged mortise. The ones that do have pegs in their small tenons do little work beyond holding the brace itself during raising...Unlike the "dove tail" which does indeed do "more work" when well executed and better pegged/wedged...

I would offer that of all the systems found in Europe the longer "pass through" (or by) bracing of the Swiss and French systems do the "most work" of all the "oblique systems" of bracing we find in European designs. I would not disagree in either of these recommended modalities, though the are not the only "simple systems" that exist historically in timber architecture...

I would not go beyond this level of discussion detail further so as not to distract from TCB's post topic, and perhaps take this offline if there is a need to explore any details further about "bracing systems."

Regards,

j
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#33599 - 03/17/16 09:00 PM Re: Double-Wall Enclosure Concept [Re: D L Bahler]
TCB Offline
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Registered: 02/10/16
Posts: 26
Loc: Texas Hill Country
"The theory behind the long slanted bracing in German building styles is that a brace to a post compromises its integrity, so the braces here join to the sill and the top plate. This results in a lack of any triangles, so rather than relying on the immutability of the angles of a triangle to maintain squareness of the walls, we are relying on the fact that the brace has to stand upright for the walls to shift."
I think I understand the concept, now, which makes it a lot easier to visualize how my design should proceed. The purpose of this system is to reduce the vertical/diagonal structures composing the wall into purely tensile/compression load paths, which resolve into point loads & moments along the horizontal plates (which from what I can tell are themselves among the more beefy structural elements, often composed of an upper & lower beam sandwiching the floor joists).

Makes a lot of sense from a load-efficiency standpoint, since vertical wall elements are typically long & lanky, therefore ill suited to carrying moments specifically (though not so long as to buckle under compression loads with even modest stabilizing braces along their length). Likewise, the horizontal plates only span between posts, which is far shorter a distance than the height of each story, and are very rigidly attached at these points, the result being far less deflection for a given moment. Seems inherently stronger for a given timber size than shorter (stiffer) braces at 45deg angles that terminate in the middle of the posts. I have noticed that a lot of the traditional Riegelbau frames seem to use similar-looking sharp angled diagonals, but break the wall into a tight grid with more frequent horizontal members --I presume this is to break up a daub-style infill into more manageable chunks?

So I suppose the tactic is to design the walls as though the columns are masonry (i.e. no bending, no tension), the diagonal braces steel rod (tension/compression only), and treat the floor as 'rigid' for all intents & purposes (reinforcing it as needed to get its loads to acceptable levels later on in the design)

" Also, "oblique bracing" modalities also function better in the "buttressing context" (i.e. at the base of a post) and can also work very well in the "horizontal" configuration within floor and roof systems as well. (i.e. "strong back" and "dragon beam" systems)"
Dragon beam as a floor support? Color me interested, I thought it was a roof-only thing (and Google search for 'Dragon Beam' helpfully yields mostly fantasy-art featuring reptiles). Since I have an octagonal floorplan, the typical rectangular joist/support systems don't seem like they will fit nicely, but a dragon-looking angled junction coming in to cover triangular areas seems feasible; any good examples of a floor structure done this way?


This is a rough sketch of how I'm laying out my walls; this is a single 20ftx10ft side of one floor of the structure
-4X's are pictured, but I'm mostly just laying out locations here
-33" centers*
-Top plate rests between the inner/outer posts on the tie-bars
-Diagonal members sit between the posts, joined to both plates (they would be entirely hidden by the plank-based infill I've proposed)
-Dashed lines at the ends are where the wall panels meet; horizontal members will be lap-jointed for attachment
-The short horizontal intercostals are for attaching (non-structural?) interior walls where needed --aircraft-style)
-The long horizontal member is that intermediate sill which forms the internal routing path for utilities

*Since such a simple sketch doesn't convey much information on its own, I wanted to explain my approach a bit more. My goal is to create a 'wall plan' that is adaptable to the other fifteen walls (down to 'interchangeable' beams), and can be easily tailored for the various doors/windows/walls that lie on it. I figured that if I get a good solid structural box at the sides, I'll be able to more freely remove, shift, and replace the structure between the second posts from each end as desired --being octagonal, each of those boxes will tie to an adjacent wall to form a ~5ft wide shallow-V-shaped column at the corners. So for the north-end of the structure with a second floor to support, there will be more posts to carry floor joists, whereas the south-facing side with only a narrow cantilevered walkway inside & outside can be pierced by good-sized windows along with the second floor.

I plan to analyze the structure with none of the intermediate framework between the second to last posts present; wherever loads show deficient, I'll go back and verify whether or not the posts in the middle pick up the slack, or if the posts/plates need to be beefed up to get below acceptable limits. Think of the building like two Gazebos stacked on eachother (hey, that's a cool idea)

TCB

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#33600 - 03/17/16 09:08 PM Re: Double-Wall Enclosure Concept [Re: TCB]
TCB Offline
Member

Registered: 02/10/16
Posts: 26
Loc: Texas Hill Country
"And this does indeed...from an engineering perspective (having discussed this numerous time with my own PE I work with)... form a "triangulated system" of compressive resistance, which is the primary function of most of the working systems within the "oblique bracing" modalities"
I agree it is effectively a triangle, but there are ultimately four members involved instead of merely three, so I guess a trapezoid with one really short leg? One aspect of the design that has me thinking is the low buckling limit of such a long support on the side of the frame in compression --the longest leg of the structure is always in compression with this system. Granted, it only takes an intermediate support or two to mitigate the risk of crippling, and I suppose the compression load certainly does serve to strengthen the truss over a joint scheme that ideally only carries tension (whatever that may be)

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#33601 - 03/20/16 02:47 PM Re: Double-Wall Enclosure Concept [Re: TCB]
Jay White Cloud Offline
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Registered: 11/06/08
Posts: 484
Loc: Vermont
NOTE: Text in "Blue" have links attached.

Originally Posted By: TCB
Dragon beam as a floor support? Color me interested, I thought it was a roof-only thing...any good examples of a floor structure done this way?


Only a few photo links...here and there under... "Dragon Beam" ....when doing searches in "English."

"Quotes" around search topic often yield better results, and "like this" searchres within context searches expand the information further...

Originally Posted By: TCB
I agree it is effectively a triangle, but there are ultimately four members involved instead of merely three, so I guess a trapezoid with one really short leg?


As I wrote earlier, these large wall oblique bracing systems are absolutely the strongest and best application of any oblique system one could employ within the...roof, wall or floor diaphragms...of a timber frame structure...

They are the primary "triangulated resistance forms" found in Middle Eastern and Asian design modalites...WHEN...they do employ an oblique bracing modality...Which they do employ in key areas more often than many "students of architectural history" believe to be done. Because they are so often in roofs and floors...and/or employed outside the typical European context...they are not generally noticed or understood by casual viewing..

I tend to find and see Asian application of "oblique systems" to be the best applied and understood forms found for resistance to extreme tectonic loading. Since the "building environments" these timber framing styles evolved in are some of the most seismically active zones in the world...naturally the understanding of "strengthening and resistance to racking"...modalities would evolve to be some of the most advanced in the world...

This is further borne out, and considered reasoning why we find a significant paradigm shift in some of Southern and Eastern European timber framing systems, and why the significant regional differences and uniqueness. As such...we find radiating from the connective tectonic plates emanating from Jura Mountains...down into the end/edges of the Iberian peninsula, through all of the Apennine peninsula and into regions of the Anatolian peninsula, very different timber framing styles to what is found in Western Europe.

Middle Eastern throughout Asian...Timberwrights have learned to employ both..."flexure and Locking"...racking systems to work in concert with one another...The "horizontal bracing modalities" of Japan (without expanding the disucssion into Korean, Chinese and Hymilian systems) reflect strongly this architectureal developement style...Moya, Tsumabari, Koyabari, nokigeta,....and most critical...the Nuki...all work extremely well to resist racking while still providing flexability within the structure. Some systems employ these almost exclusively in very seismically active zones, some also having oblique systems within the floors, roof, and perhaps wall corner intersections as well. Most being very large in triangulation, many in a "horizontal configuration, and most connecting within the context of "sill and plate" configuration.

Ketayuki sujikai, Koya sujikai, and very importantly the Hiuchibari found within floors and ceiling assembly...are all very critical "oblique systems" found in these timber framing modalities.
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#33602 - 03/20/16 04:27 PM Re: Double-Wall Enclosure Concept [Re: Jay White Cloud]
TCB Offline
Member

Registered: 02/10/16
Posts: 26
Loc: Texas Hill Country
Thanks for those keywords, Jay! Most references I find to Japanese joinery are the elaborate temple-style stuff, which isn't very practical for a pedestrian job like a house (or very easy to understand, for that matter). This stuff seems more ground-level from what I can see.

I also think I understand what you describe as far as flexibility. Many of these joints seem arranged so as to be at their most flexible when in the 'nominal' position (like a horizontal beam passing through a mortise --Nuki, right?-- which is most 'loose' while the structure is square, but will react with a fairly strong moment as the structure flexes. True locked-in triangular braces will only flex as much as the wood fibers in compression/tension (i.e. not much). I can see how one is good for dealing with earthquakes, but one may be better at resisting heavy snow loads or high winds without deformation (i.e. damage to infill or windows).

Almost seems like the difference between ye olde school riveted bar steel truss structures vs. more modern welded-beam forms; one is a heck of a lot 'looser' than the other, though both are capable of being plenty strong, and standing up straight (and lasting a good long time)

This is central Texas, though, so seismic concerns are, well, less of concern than in the Ring of Fire (or Oklahoma these days, for that matter). There's a big fault here, but it's pretty stable and expected to remain so. The real issue is drought moving soil around beneath a foundation, but that's more on the foundation that the walls to deal with correctly.

I did notice a long diagonal stiffening frame in many of the structures linked, which is at least visually similar to the Germanic forms and reminiscent of what I posted above. However, it is hard to see exactly how/where it attaches; it looks to jut straight into the corner between post & lintel. Are these usually fitted to the horizontal plate, or into the post beneath the plate joint (or both)? It would seem that terminating the diagonals on either side to a splice put through the post would be a sort of best of both worlds.

I'll also look into Spaniard timber framing schemes a bit; I didn't realize they had a unique tradition of their own (as opposed to borrowed French or Moorish forms). When I traveled to the mid/western portion years ago, it seemed that sand stone was the preferred material, even down to melted-looking ruins of ancient farm huts out in the country. Granted, tall straight trees were uncommon vs oaks, there weren't many of either, and sand stone is pretty easy stuff to quarry & shape into block. Spain's a big place, and I'm sure the more North/Eastern portions are into timber.

Any keywords I should home in on?

TCB

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#33603 - 03/21/16 02:50 AM Re: Double-Wall Enclosure Concept [Re: TCB]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 484
Loc: Vermont
Originally Posted By: TCB
Thanks for those keywords, Jay!


You are most welcome...!!!

As a teacher, helping students of all ages (and topic interests) it has been a passion of mine for a number of decades now, to really engage in the different medium processes of..."good research."

Whether "tomb" or "internet" I learned decades ago to..."go to the source"...whenever possible. In this case with "the web" that means learning to do research in the "original languages," of the topic one is interested in. This is the way the internet algorithms function. Japanese Kanji, Korean Hangul, or Chinese Hanzi (as just some basic language groups much different from the "English alphabet) all have a vast and far reaching base of knowledge and information capacity to share on all subjects...even one as seemingly esoteric as "timber framing."

Originally Posted By: TCB
Most references I find to Japanese joinery are the elaborate temple-style stuff...


For the most part...that is too true...

Most of what "Westerners" see, learn or read about (in English) is a very bent, romanticized, and/or narrow scoped perspective too often based on "Eurocentric" perspectives, viewpoints, understanding, and/or interpretations...It isn't until one get to really embrace an "indigenous perspective" that one can truly learn (or begin to learn) how a topic actually is perceived by a culture or societal group...

I like your desire to seek the "practical for a pedestrian" as that has been my primary focus in the guild arts in general and timber framing in particular...

I have love and began specializing in "folk styles" decades ago...particularly in regions from Native American, Middle Eastern, African, and of course throughout the vast content we call "Asian." I fell in love with the charm and pragmatic grace of the folk styles, like Minka, Hanok, Chise, Daji Derweri, Kath Kuni and the list goes on...

Originally Posted By: TCB
I also think I understand what you describe as far as flexibility...these joints seem arranged so as to be at their most flexible when in the 'nominal' position (like a horizontal beam passing through a mortise --Nuki, right?


Excellent!!

Not only are you getting it...you keyed in on one of the most beautifully simplistic (and most practically functioning) systems...the Nuki horizontal beaming modalities...

Having studied now a vast array of timber framing styles around the globe from Native American, African and European...I can state emphatically, there hasn't been a system that "stiffens" a frame more rigidly as these "horizontal modality" while still giving the timber frame a degree of "flexibility" that triangulated systems simply can not achieve...no matter the format...

Oblique systems do have there place, yet can never achieve the "stiffness with flexibility" that the "horizontal bracing system" can...which is paramount for a frame to last thousands of years when subjected to heavy and/or extreme ongoing tectonic loading...Such as one finds in places like the Himalayas, and Japan as just two prime examples...

Originally Posted By: TCB
...which is most 'loose' while the structure is square, but will react with a fairly strong moment as the structure flexes...


AGAIN...precisely stated!!

These horizontal systems "fail" in a slow, relaxing fashion (for the most part) and not in a catastrophic way, as do most (if not all) oblique systems...

A "triangulated system" whether at 45 degrees or some other less critical angle, will hold rigid and stiff extremely well...Unfortunately they also tend to fail "catastrophically" when they do finally give way to an over loaded critical scenario. They tend to come down fast and very hard, once the load capacity of the frame has been max capacity, often completely blowing apart the timber frame of which they formed...In in a region like Japan...especially areas with daily earthquakes found in some range...a forced evolution of timber framing took place over millenia that would allow the frames to become able to "slowly fail"...and/or "rack" in severe situation while not collapsing completely...while sacrificial members (like nuki) where slowly crushed...This also allowed frames to be more effectively salvaged and/or simply un-racked and "stiffened by the placement of key "wedges" and new lighter timber members...such as the Nuki...

As you so rightfully noted further...in regions like Hokkaido...you will see both the oblique systems (often in the horizontal format like Hiuchibari of in the roof or sill/plate orientation) and the "Nuki systems" working in concert with one another...

Because there we find not only high winds and earthquakes but also massive snow loads that literally cover communities under meters of snow each year... In such places as this, one must have a frame that can be massively stiff to support the snow's weight, yet also have a system within to allow greater degrees of flexibility not found in most European modalities...As you say..."the best of both worlds."

Originally Posted By: TCB
I did notice a long diagonal stiffening frame in many of the structures... it looks to jut straight into the corner between post & lintel. Are these usually fitted to the horizontal plate, or into the post beneath the plate joint (or both)?


It depends on the region and applications style, as we have just begun to scratch the surface of these different systems of timber framing...which vastly outnumber what we find in Europe if taking in the entire context of Asia, and then the Middle East, Africa and the Americas.

You are more than getting the most germain aspects however...it is a beautiful and most graceful mix of..."both worlds." In general perhaps the most "globally applicable" systems one could find and/or adapt to "modern timber frames" and there current applications. "Asian design" modalities...with there heavy and dominating reliance on "horizontal systems" (both oblique and horizontal "pass through") allow better facilitation of fenestration and many other design aesthetics one finds and/or desires within "modern designs." This is one of the primary reasons "Green and Green", Gustav Stickley and many other founders accredited to the "Craftsman movement" here in North America, turned to the purity and pragmatic functionality of Asian systems...

As for Spain...it is a big place and does contain many different biome types that often "visitors" don't get into on typical vacations to the Iberian peninsula...One very unique form that has a millenia old ancestry (one of the oldest in Europe) from well traveled sailors and long traveled fluences...we have the Hórreo system of timber framing which is very beautiful and unique...They appear greatly unstable, yet withstand earthquakes, and massive weight as most function as store houses, barns, and granary. Note again the lack of "oblique bracing" in most of the designs found in this system of stone and timber architecture...except where absolutely critical...

Originally Posted By: TCB
Any keywords I should home in on?


Gosh!!

Where to begin, of which culture and what language??? shocked wink grin

I have been compiling information for decades and still learn more each year...

It is sometimes pleasantly overwhelming just how broad and far reaching this great craft of timber framing has been...and just how...Non-European...most of it is in design and natural aesthetic...


Edited by Jay White Cloud (03/21/16 02:52 AM)
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#33604 - 03/21/16 06:58 PM Re: Double-Wall Enclosure Concept [Re: Jay White Cloud]
TCB Offline
Member

Registered: 02/10/16
Posts: 26
Loc: Texas Hill Country
"A "triangulated system" whether at 45 degrees or some other less critical angle, will hold rigid and stiff extremely well...Unfortunately they also tend to fail "catastrophically" when they do finally give way to an over loaded critical scenario. They tend to come down fast and very hard, once the load capacity of the frame has been max capacity, often completely blowing apart the timber frame of which they formed...In in a region like Japan...especially areas with daily earthquakes found in some range...a forced evolution of timber framing took place over millenia that would allow the frames to become able to "slowly fail"...and/or "rack" in severe situation while not collapsing completely...while sacrificial members (like nuki) where slowly crushed...This also allowed frames to be more effectively salvaged and/or simply un-racked and "stiffened by the placement of key "wedges" and new lighter timber members...such as the Nuki..."

Well, the fact I have parallel vertical posts in close proximity to each other suggests that style of jointing may be desirable (specifically for my top plate and/or floor joists which could theoretically pass through both 'layers' of wall posts). Is a slot like that vs. a partial mortise better suited to thicker timbers, though? My only concern is I'd be boxing myself into using fatter sticks than really needed.

While a system like you've described can be more flexible, when it does come time for it to load up, it is inherently less efficient than a cross brace, for the simple fact the crushing/binding/etc is occurring right at the brace point where the lever arm is tiny. Also, as you mention, for loads applied more locally to the structure than seismic ones (i.e. a wind gust) a more rigid structure will handle it better without disruption, and triangular braces are ideal for maintaining shapes under load with minimal material. Definitely two different schools of thought, but I'm not convinced they are mutually exclusive; perhaps a system of cross braces that only operate in tension or compression (but not both) in concert with flexible braces would yield a system which is quite rigid in normal conditions for the size of its timbers, but still possesses a sort of 'fall back' progressive failure system in enough of its structure for the brace members to fail without immediately ending the structure overall. No reason for the building to be flexible except when its life is at stake, right?

I suppose some built in flex with 'tunable' bracing might make a raising go smoother as far as fitting of the walls to each other; any thoughts on that? Maybe 'loose' cross braces that are either wedged or drawn with trunnels to stiffen things up after being squared? The tensioning elements alone would hold things until the structure deflects enough to load the joinery.

I also wonder if the flexibility only really needs to be present at the ground floor or only at the upper floor (depending on whether seismic or wind loading is the issue). Probably getting into really complicated dynamics issues if we think too hard about this, with no easy one-size answers. Being a two-floor system, does the progressive-failure character of these joints still hold? Simply because the two stories of a timber frame don't seem to ever be joined nearly as strongly as the bents making up the walls (i.e. in a severe racking situation, the upper floor would simply pop some mortises tying it to the plate & fall off)

"As you so rightfully noted further...in regions like Hokkaido...you will see both the oblique systems (often in the horizontal format like Hiuchibari of in the roof or sill/plate orientation) and the "Nuki systems" working in concert with one another..."
Hmm, this sort of goes back to my thoughts on whether/where one design format is advantageous over the other. The flat/horizontal frames that make up floors/roofs aren't really subjected to the type of resonant torsion loads that buckle vertical columns, since the foundation kind of insulates the structure against vertical-axis shear for the most part (squeezing a rectangular floorplan into a parallelogram). That type of load would always be accompanied by a general twisting of the vertical structure about its axis, neatly racking all those nuki joints more or less equally (dissipating what little shear load would be resisted by the diagonal braces). Well, unless the actual fault slips under your foundation, anyway (good luck with that)

So I suppose the lesson might be to use rigid joints where you expect the least movement (vertical-axis shear) and allow for more flexibility elsewhere. I guess that's sort of self-evident; make the roof super rigid & structural (as Asian roofs typically are, if I am not mistaken) but let it 'float' on a self-centering pedestal.

One thing I do notice on the Swiss/Germanic buildings, is they seem to be more vertical in general, with more floors and greater height. Obviously the fault lines have much to do with this, but I also imagine you'd have a hard time getting flexible joints to deal with a three-story structure (harkening back to my stupid youth, I climbed an ancient and lighting-blasted forest-ranger tower ~40ft tall which was constructed of riveted flat steel bar; I've never ever been on something so wobbly in even a mild wind, but I'm told they were always that way & actually can survive high winds & tornadoes better with moderate damage). For whatever reason, I'm thinking that the tallest structures in classic Japan tended to be inns/tenements, which were quite tall (relatively speaking); what styles might they have tended toward?

"Where to begin, of which culture and what language???"
Sorry, I was referring to Spanish forms, specifically, at least as far as how they may differ from Swiss/Germanic while still emphasizing material efficiency. I'm afraid I won't quite be willing to learn a whole new language (in a technical field, no less) in order to build a house! wink --I can ask for the bathroom or a glass of OJ in Espana, but not whether you run a trunnel through the gusset vs a scrivet into the mucket (those last two were actual words from my automotive maintenance manual) and more importantly, whether you'll kill yourself doing one over the other, lol!

TCB

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#33605 - 03/23/16 09:08 PM Re: Double-Wall Enclosure Concept [Re: TCB]
D L Bahler Offline

Member

Registered: 05/17/10
Posts: 946
Loc: Indiana
For what it's worth,

German colonists in Central America brought with them their traditional timber framing forms and put them to use in the New World. Many of the places where the Germans settled were earthquake prone. However, the German building style survived, and proved its ability to withstand earthquakes. Some of the original colonial ear buildings are still standing. Regions with German heritage are easy to spot by their steep-sloped roofs and tendency toward half-timber construction while their neighbors tend toward a more Spanish style of building -so yes to answer your question there is indeed a strong Spanish school of timber framing, and we can find it in practice still among their descendants in south in Central America (who are estimated to be something like 80-90% Spanish by blood in most areas, due to the impact of European diseases which nearly wiped out the native population in all but the most remote regions.)

I do have a bit of background is seismic engineering. I'm no expert by any means but I understand the basic concepts, and maybe a bit beyond that. The notion that buildings must flex during seismic loading, as stiff ones will fail, is a bit of an over-simplification. Stiff buildings can do well, provided they possess the structural means of dissipating the seismic forces. I can't recall where I read it, but I do remember having read that the German Fachwerk (light frame and brick infill) are able to withstand the earthquakes because they are very efficient in transferring the energy out of the frame. By pure luck, the frames the Germans brought with them that were not designed to resist earthquakes proved capable of doing so. I'll have to track down my sources on this, I'm sure you'd be interested in it. Even in the US today, some seismic engineering relies on flexibility while others are designed be stiff and very efficiently transfer the forces (with unpredictable direction and intensity but predictable origin, i.e. you know an earthquake will attack at the foundation) out. Both have their own advantages and drawbacks.

When it comes to buildings lacking oblique bracing, this is not a strictly Asiatic phenomenon. Actually this concept is likely far older than the use of bracing as we are used to it. In a sense, you could say the Japanese method is considerably more archaic than anything used in the West today. Similar concepts appear (we can't know for sure, as we have a very limited amount of information to work with) throughout the Mediterranean. Greek, Etruscan, and by extension Roman architecture -while classically in stone, derives from a type of wooden architecture that did not involve any sort of long bracing members but rather relied on locking joinery at the tops of the posts and interlocking bracketed timbers in the roof (according, at least, to Vitruvius and other Roman era writers who were writing a few centuries after the last of these structures were built) Classical stone architecture reflects this, the capitols of the columns and the construction of the portions above the columns all reflect the wooden origins. Even Egyptian architecture reflects similar origins, with early Old Kingdom stone architecture emulating reed bundles and palm logs used to construct their immediate predecessors.

We can find some similarities here; Italy, Greece, and much of the Ancient Near East are all earthquake-prone, and they appear to have at one time used techniques very similar (if not considerably less developed) to what we still see in east Asia today.
The simple explanation as to why these sorts of techniques are not found in the west today is that Mediterranean and Mesopotamian cultures typically abandoned timber framing methods in favor of heavy stone architecture (or in some cases never possessed suitable timber resources to ever have any sort of rich timber building tradition). The timber frames in the former Roman world today stem from largely Germanic or central Asian (Turkic and Hunnish) sources, and as such spent a few centuries developing in a totally different part of the world.

So all of this long-winded talk is to illustrate the point that all of this is far from simple, and very little understood by anyone. There are a lot of different approaches to Timber Framing in general, some spectacular and some not, but all with something worth studying. There are many different solutions to bracing, each with its own set of advantages and disadvantages.

The German system was designed with a goal in mind, that goal was to create a style of building that was as efficient as possible from a materials standpoint while maintaining and even increasing upon the ability of a timber frame to endure loading both static and dynamic. In the early industrial era this design was pressed even further, and the northern Swiss styles of rural Riegelbau construction are the result of this push for efficiency.

Asian tradition seems to be driven by a different set of values. This is not by any means an insult, just an observation. The Japanese as I understand it refined their systems into a delicate art -like they did with most things. The craftsmanship is superb and their accomplishments admirable, however we do well to recognize a different set of ideals behind their developments when contrasting with European systems.

Also I should say this; there are indeed braces that are designed to work only in tension. I've seen hundreds of them (if not thousands) during my travels. This used to be a very typical Central European phenomenon. Many structures with light plank infills relied on thin (like, 1 or 2 inch) plank braces on the outside to hold the structure. These relied on tension joinery -in this case a family of refined and specially designed dovetail-like joints- and were useless under compression. In fact, some joints appear to have been designed to 'pop out' if the braces came under compression, this same shape of the joint causing it to become tighter and stronger under tension. This type of joint evolved as a solution to the challenge of having to add braces after the walls, infill and all, were erected. The only practical way to do this was to use relatively thin braces that were inserted from the outside and face-pegged in place. This is an almost universal feature of old central European and Alpine timber frames relying on light plank infill, and is recognized as a Celtic technology (in contrast with archaic Germanic technologies that relied on let-in bracing that appears to have been designed to work primarily under compression, for example the bracing used in Anglo-Saxon and early Norman ere English structures). I am not aware of this technology existing anywhere else. It is worth noting that structures I have seen this sort of bracing on range in period of construction anywhere from the early 19th century to the late 13th century. For the most part, Swiss rural carpentry tended to view tension as the primary action of effective bracing, and the designs of their roof structures especially reflect this.
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#33607 - 03/24/16 06:06 AM Re: Double-Wall Enclosure Concept [Re: TCB]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 484
Loc: Vermont
Originally Posted By: TCB
Is a slot like that vs. a partial mortise better suited to thicker timbers, though? My only concern is I'd be boxing myself into using fatter sticks than really needed.


Sizing (typically) in most of these "pass through bracing styles" is proportional to one another so a post can be very small. I have seen examples where there may be more post in a small format (75mm), and the nuki are a 1/3 corresponding element that passes in the middle...

Originally Posted By: TCB
...While a system like you've described can be more flexible, when it does come time for it to load up, it is inherently less efficient than a cross brace...


I would agree...perhaps...in some "borrowed" or modern "bastardized" examples, yet not so much in the traditional formats...

I would also suggest that many (most??) folks that I have conversations with about these systems (and their "concepts/ideas" about what they "think" may be taking place) have never studied them "in country" or ever designed/built with examples of them...Until that is achieve, it really is not tangibly possible to give a complete contextual understanding of them...

It took a very long time and a great deal of academic and in situ examination of these systems (including building examples of them or testing them to failure) to get a reasonable understanding of just what does take place in crushing/binding load situations...comparably that is to other system. As described earlier, Asian and Japan in particular has been afforded a biome and climate type that is very unique. Not only heavy snows, and severe tsunami/wind events but the ever pressing seismic loads the architecture has to endure regularly...

Originally Posted By: TCB
...Definitely two different schools of thought, but I'm not convinced they are mutually exclusive...


Fully agreed, and I think I reflected that in the last post, as in some areas of Asian and the Middle East you will typically find both systems working in context with each other very well. We have now lost the oldest examples of some of these in Syria to the devastation of war. There "was" a structure there just in its final examinations indicating an age of over 7000 years for portions of the structure...Regrettably, it and the examples around in no longer exist for further study or examination...

If we move into examples like Dhajji Dewari and kath khuni ...as just to contrasting regional styles not that far removed from one another...we can see different solutions for building while using similar resources in different context...One that heavily relies on an oblique system and massive weight and the other only horizontal bracing and massive weight...While others of this region will employ a concert of both...

As mention, some of the Norther Japanese systems (et al for the Himalayas) employ both systems also...as you say...a "fall back." Yet most of what I often read in discussion like this are "theoretical examinations" and/or just loose academic conversation...One most go there and/or build with these system to fully understand them past just intensive literary research...

Originally Posted By: TCB
...Probably getting into really complicated dynamics issues if we think too hard about this, with no easy one-size answers...


On that point...we are in full agreeance... wink

As for whether "two-floor systems" can rely on these system...the answer would be yes...but again not out of context from a very well defined system of design...The oldest "well documented" timber frames in the world are in Japan, and these are often Buddhist temples and Sutra repositories that may be as tall as six stores...or again...like the Kath Khuni of the Himachal Pradesh averaging 4 to 8 stories in some examples...

Originally Posted By: TCB
So I suppose the lesson might be to use rigid joints where you expect the least movement (vertical-axis shear) and allow for more flexibility elsewhere.


Very well stated...and getting to the heart of many of these vernacular forms...Massive rigid roof systems with huge mass, and then central column along with flexible torsional resistance systems in other areas...And/or corbelled/bracketed...which can be looked at as a "flexible oblique system" such as most Dou Gong bracketing system.

Originally Posted By: TCB
...For whatever reason, I'm thinking that the tallest structures in classic Japan tended to be inns/tenements, which were quite tall (relatively speaking); what styles might they have tended toward?


I am not sure that is really accurate...??

Most "merchant or Samurai" class architecture is single story...While Minka structures with there "Gossho" (aka "Praying Hands") style steeply pitched roofs may be called 5 to 6 stories counting there attic/upstairs areas...When you move out of Japan and deeper into southern Asia and the Middle East...the styles get even more numerous...

Many systems (even those shared in this conversation) are multiple stories tall and forming some of the tallest in the world...Many of the Asian Castles (like those in Europe) are built of massive stone foundations and then huge fortress timber frames above...Then we have Kath Khuni, Sutra Pagodas all over Asia, many 3 and 6 story timber frames throughout very tectonically active regions of the middle east such as Kashmir's Taaq, and on into Bhatar, Leepa style timber frames etc...many 3 stories or more...

Timber-framed houses in the Hımış, Bağdadi styles (et al) form 80% of the total number of houses registered as cultural objects in Turkey. Being located on the Mediterranean-Himalayan seismic belt. These structures are greatly affected by earthquakes...and many of these domestic homes are over over 4 stories in height

I can more than understand the challenges with "languages" I struggle enough with just my own crazy and the few others I am slowly learning...For a house build...just ask others that have their nose stuck in all the different joint styles and ask good questions like you have been... grin


Edited by Jay White Cloud (03/24/16 06:15 AM)
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#33608 - 03/24/16 06:41 AM Re: Double-Wall Enclosure Concept [Re: Jay White Cloud]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 484
Loc: Vermont
Sorry about the typos at the end...Our forum here will not use many different kinds of font or Kanji...

the names where...

Himmis which is not that actual spelling but close...

TCB (et al) you may also find this presentation interesting for a collegue/mentor of mine...Randolph Langenbach

Bagdadi

Talk on tall timber frames and earthquake resistance in the vernacular forms...


Edited by Jay White Cloud (03/24/16 06:51 AM)
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#33610 - 03/24/16 11:32 AM Re: Double-Wall Enclosure Concept [Re: TCB]
D L Bahler Offline

Member

Registered: 05/17/10
Posts: 946
Loc: Indiana
The oldest standing timber frames in the world can be found in Italy, in the excavations of Pompeii and Herculaneum, both of which were buried by the eruption of Vesuvius in 79 AD.

These timber frames should prove interesting to you, Jay, and TCB also.

This is the style Vitruvius calls Opus Craticium and it looks like this:


This is a sort of construction that was used chiefly for apartments and low-end housing, according to Vitruvius (and the example shown supports this, as it was an apartment complex). He thought it inferior a a tremendous risk for fire or falling down.

Of particular interest is the complete lack of any sort of bracing, excepting the double horizontal construction seen in the first picture at the top of the walls. The buildings appear to have relied almost entirely on the infill to maintain their shape.
This example is of stone, though Craticium refers to reeds and Vitrivius spoke generally of an infill more like waddle and daub (thus his aversion to the system as cheap and prone to fire)

Some historians speculate Medieval Swiss and South German half timbering may have roots in this style of building, due to the obvious similarities (The Romans may have adopted it from Syria or Persia, by extension suggesting a possible ancient link with the Dhajji Dewari or the Himis style practiced in modern Turkey.
I am skeptical of any strong relationship, other than the idea that the Romans were the inspiration for the concept of Half timbering in Europe while the overall framing methods tended toward the systems used in all wood construction from various Germanic and Celtic sources.

It should be noted that the structure in the picture is said to be in a dangerous state and is not open to the public.
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#33612 - 03/24/16 03:22 PM Re: Double-Wall Enclosure Concept [Re: TCB]
Jay White Cloud Offline
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Registered: 11/06/08
Posts: 484
Loc: Vermont
I have been to the Herculaneum Ruins...and the "house opus craticium" (a misnomer in description...watch the referenced video above...Randolph makes reference in his lecture.)

Some of the structures there can't be entered by "general public" but interior spaces are still accessed and studied by academics. The structure in the photo is on a public street and can be walked up to and viewed in (according to recent visits by students/friends)...but not entered do to public wear and tear on restoration/reconstruction work pending...

It is most precious and unique...and a wonderful example of some of some of the "oldest styles" of infill timber work, but the work in the photo (or much of it) is "new reconstruction" with elements of the original contained within as "historic interpretive display," as this is a "rebuild," from ruined elements during a pyroclastic event...

When discussing examples of "oldest structures" (wiki has many errors in it...) to meet standards set down by UNESCO, the Burra Convention, et al...the structure must be original, documented fully in context, and still standing on original foundation (in most examples) with most of the original material contextually still in use without "reworking."

The "oldest wood structure (or timber frame)"....is currently in Japan and before the destruction of it...the architecture in Syria may have surpassed it by over 4000 years...unfortunately now we will never know as the research has ceased and the village that contained it gone...


Edited by Jay White Cloud (03/24/16 03:28 PM)
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#33613 - 03/24/16 03:51 PM Re: Double-Wall Enclosure Concept [Re: TCB]
D L Bahler Offline

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Registered: 05/17/10
Posts: 946
Loc: Indiana
The house in Herculaneum is not mostly new construction, this is well documented and can be easily researched. This house was discovered mostly intact with furniture and cupboards filled with everyday fare. What you see of this house is mostly what was originally there. There was a very small amount of restoration done to keep it in fairly reasonable shape, but the vast majority of the structure dates to its construction some time after 68 AD. It is considered to be the only fully intact example of this style of building still in existence.

Still this is not entirely fair. The building was buried in ash with pockets of poisonous gasses, preserving it in a moment of time. It's not a testament to the longevity of the style -which even if it is not the same style Vitruvius calls Opus Craticium was still reserved only for the cheapest construction in Roman Italy (we deduce this by the fact that all of the finer buildings are made of stone and brick). If it were not in the perfect place at the perfect time, this building would likely have suffered the same fate as every other example of this the Romans ever built -it would have fallen down.
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#33614 - 03/24/16 04:52 PM Re: Double-Wall Enclosure Concept [Re: TCB]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 484
Loc: Vermont
David, this is not worth debating...Go there, talk to academic that study this region (et al)...There is a great deal of "mis-information" on the net...We can agree it is old, and very important to the architectural record...
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