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#32745 - 01/24/15 10:17 AM Re: 6x6 joist spacing for workshop floor [Re: timberframe]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 480
Loc: Vermont
Originally Posted By: Brent
Completely understood! To be fair, no aspects of the math intimidate me, I'm just partly being lazy and partly uncertain about the different loading scenarios because I haven't had time to read up on them yet and time is getting short! Good to see confirmation my understanding of the concepts and principles are sound though!


Hi Brent,

I figured you could muddle through the math...but...like the rest of us, its just nice to "bounce concepts" of others. I just try to always plug in the disclaimer...just in case someone is trying to DIYer a frame over their heads.

Thanks for understanding...


Originally Posted By: Brent
So a few more details. We are doing a rubble trench scenario with short stem wall, but also stem walls running across the building under the bents upon which another 8x8 "sill" will sit. Since the bents are 12' spacing and the building is 24' wide, the interior space that is to be filled with the raised wooden floor is 24x12'. So joists going across the gap the shortest way are 12' long and will join with 8x8s that sit on concrete. Maybe you figured that out, but I just wanted to make sure!


That sounds like a very solid foundation...:) All we use is gravel trench and stone most often when we can get away with it. The trend today is to "throw" concrete at everything and think that is better. I always get a kick out of folks that don't think stone is stable enough...Often while they are standing inside a vintage timber frame that has been sitting on stone for a few centuries.

Your foundation (assuming the concrete is of good quality) should be around for at least that long...

Originally Posted By: Brent
Absolutely. This is why I'd planned on a fully housed dovetail.


Excellent...and to be clear...this means the entire end of the joist is housed into the 8x8. I do like Timbeal's suggestion "tusk" or "soffit" tenons. "Overlap" where the heel of the joist is house and the rest extends over the sill is also excellent. This would save you a great deal of joinery cutting...actually be stronger than the dove tail and would only ad at most 2" in elevation gain in one of the possible renditions.



Originally Posted By: Brent
Wondering about the legendary strength of my full 1" T&G white oak though and how much ply material would be required in concert with this? Would love to have plank underlay, but didn't have time to saw the material.


Hmmm....Well, it all depends on the joist spacing...etc. You will need a minimum of 2" for the kind of loads you are possibly subjecting that floor to...So...it all depends on the final configuration chosen.

Originally Posted By: Brent
Alternatively, what if I made a slightly wider stem wall such that wider and deeper joists could rest on the concrete itself with no housing in the sills. Could even consider 8x8 joists with dovetails cut in the ends to tie everything together but a housing would be exchanged for a good bearing surface on the wider concrete. I could cut some more joists, and save the 6x6 for other projects. I'm cutting it tight already for height on on the first floor, and already have the posts cut so I can't really put joists on top of the sills.


In general Brent...it will be your call. I am not fond of "dovetail joints" in general and the only ones I do like or have ever employed in a frame work in concert with other tying members and are only executed in the "Asian moralities" (i.e. Japanese - Korean forms) not European configurations. Most of the contemporary forms of this joint I have had the opportunity to go back and look at...well...not impressed with how they age.

Technically you could just set down a simple very rot resistant 2x plate (wood does not like sitting on OPC) and have the joist simply rest on the OPC stem wall with a "header sill" let into the bottom of the posts. this is more than strong enough and is the fastest foundation type we do on simple sheds, barns, garages, etc..

Good luck, and keep us up to date...Can't wait to see photos.

Regards,

j
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#32748 - 01/24/15 06:23 PM Re: 6x6 joist spacing for workshop floor [Re: timberframe]
timberframe Offline
Member

Registered: 08/23/11
Posts: 26
Loc: Canada
Excellent excellent excellent, thank you. This is all great stuff, and thanks for the diagrams too. Lots to mull over, and final decisions will be determined by timber availability etc, but I think I can make anything work.

To be honest, the DT joints to me just sort of look elegant but I hear you on the shrinkage issues and there seem to be a few votes against it. Steve seems to employ them regularly, but the are quite fussy to get right, so a more simple approach is just fine with me!

Regarding concrete....it's that combination of great stuff that's also evil. It sure is handy, but we're happy to avoid it as much as we can. We actually took a course in stone construction, and were thinking about trying this, but we're worried about biting off too much on our first building. We'll try it when we build the house depending on local availability etc.

Thanks again, appreciate it!

Brent

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#32749 - 01/25/15 06:51 AM Re: 6x6 joist spacing for workshop floor [Re: timberframe]
TIMBEAL Offline
Member

Registered: 12/10/07
Posts: 1875
Loc: Maine
Dovetails can be crude and simple and still work just as well as a finely crafted one, and after drying the extra effort will be negated. More over the elegance will only be seen by you while your cutting the joint, it gets hidden once installed.

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#32750 - 01/25/15 08:34 AM Re: 6x6 joist spacing for workshop floor [Re: timberframe]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 480
Loc: Vermont
Hi Brent,

OPC (ordinary portland cement) and the industries behind it are the primary challenge in my view. Since about 1880, when the more "energy intensive" methods...(read mass production for profit)...that moved away from "natural cements" like Rosendale when issues really began. The Brooklyn Bridge...still going strong...is stone and natural cements and lime mortars...Note, bridges a fraction its age are falling apart and being replace with...you guessed it...more of the same nasty OPC...Talk about a scam and money racket! I can't wait for Limecretes, Natural Cements and Geopolymers (Roman Cement) to start taking hold in this market...IF...the OPC Lobbyist and Industry actually let that happen...

As for Dovetail joints, the only one I have ever seen that function as intended and endure are those I have seen in Asian frames...particularly Japanese modalities. The common aspect of them...they are smaller...always hidden...and usually very deep and working in concert with other tying members in close proximity.

As for most I see in contemporary work...there is always a better joint to use...usually stronger and almost always as easy or easier to cut...

As Tim pointed out..."it gets hidden"...so why bother with a less strong and more difficult joint to facilitate?

Regards,

j
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#32751 - 01/25/15 06:55 PM Re: 6x6 joist spacing for workshop floor [Re: timberframe]
timberframe Offline
Member

Registered: 08/23/11
Posts: 26
Loc: Canada

THanks again! Do you have a link for some more info on the natural cements? Familiar with lime mortars and limecretes, but less on the others. I heard that very soon cement production will soon surpass coal fired plants as the largest source of airborne mercury in NA.

Cheers,
B

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#32752 - 01/26/15 06:58 AM Re: 6x6 joist spacing for workshop floor [Re: timberframe]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 480
Loc: Vermont
Hey Brent,

Sure do...a colleague and friend of my owns the last quarry and facilities that production of these natural cements....as well as...limes, and other related materials. His name is Mike Edison, and he is probably one of the countries leading authorities/Engineers on OPC, Natural Cements, and limes, with related materials as well. You can find his web pages at:

Natural Mortars

Rosendale Cement

One more point on Dovetail Joints for clarity, The Asian forms, though often (not always) smaller...they are much deeper in form often running almost the entire depth of the joining members end. They act and perform more like a "dovetail keying joints" than just a lapping joint form.

In historical restoration-conservation, I see Dovetail joinery as applicable in honoring the "like for like" ethos of this branch of the Timberwrights art form, so here we do employ them and as was the intentions of the original designers of any given vintage frame...Here is where they are most applicable and germane in my view.

Good luck and keep us posted!

j


Edited by Jay White Cloud (01/26/15 07:00 AM)
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