Barn comission conundrum

Hi all!
Been asked to build a barn with a perfect combination of criteria that leave me with a conundrum I'd like to ask for thoughts on. First some details:

32x65 feet, with 65 feet flexible by a few feet. SO I'm thinking 4 16 foot bays give 64 feet, no problem. It's the other direction that's a bit sticky. They want three "aisles", a 12 foot in the middle, and two 10 footers, one on each side to give the 32 feet. Eastern Canada with local timbers, so a 32 foot continuous tie beam is NOT possible, in fact we're looking at a 16 foot maximum length. They also want useable space the upstairs(not necessarily the whole footprint), so a king post truss system or hammerbeam isn't practical. Can't do a principle rafter system either as they'd be too long. A queen post setup seems ok, but I would have to break up the tie beam, which I've never had to do before and had it drilled into my brain years ago that it was best to avoid. I know it's done though, and I was just wondering about preferred way to do this. Any additional thoughts would be wonderful!

Cheers,
Brent

Here's an unfinished schematic that doesn't have all of the elements in it (it's on my other computer) but shows the offending posts which are why a change is needed. The continuous ones that go up to the upper purlins are about 21feet and though the sawyer originally said he could handle them, he can't and buying elsewhere isn't an option (long story). It's a modification of a dutch barn, so the upper, large tie beam would have actually been a wedged through tenon in that dutch barn style.

{How do I add an image that's not from a web site?}

What if I interrupted those posts at the large upper beam, set the beam on top of the posts (some tying joint there to be decided on later) and then set the posts continuing on up to the purlins on top of that beam?

B

You can't find some 32' white pine in eastern Canada? Have you looked into Dutch frames? An H bent down the center aisle with dropped ties off the sides. You can put a broken rafter system in with ease, join the rafters over the plate on top of the H bents.

Hi Tim, sorry I couldn't load the pics in the previous post, but a dutch frame with dropped ties was exactly what I proposed, however the tall posts on either side of the middle H frame (up to the plate/purlin) had to be really tall in order to leave much usable space upstairs. The sawyer being used produces great products and I've been training him (he also has a structural beam grading license) but can't do much more than 17.

Hello,

I am with Tim...The first thing I thought when I read the configuration was "Dutch Barn" and I am unclear about why you would need such a huge timber anyway? Traditional barns seldom have such clear spans until you get into "truss designs" (which are very rare) and/or "bull beam" barns which are only slightly less common (not many) to vintage Dutch Barns.

On specially projects like this one can "site select" enough trees this size to achieve that span, but I would say a PE stamp is in the future for such design and would rather suggest not "reinventing wheels" and sticking with "traditional barn formats" and layouts...Like a Dutch Barn which often had 16/12 or 12/12 pitched roofs historically.

Feel free to drop me an email or call if you would like to talk more about these vernacular styles...

Regards,

j

Hmmm, if I can figure out (or can get a pointer on) how to add a picture, I can show the Dutch style barn I proposed originally but had to reconsider when I heard back from the sawyer that the length was too long.

Our forum is a bit challenged for ease of use in some respects. Post photos in shared file like google drive or drop box.

As for the "big timber" aspect again, other than for some really long rafter plates in many Dutch Barns there seldom is a beam longer than 24 feet and often shorter.

OK, let's try this. Let me know if you can see it.
[img]https://drive.google.com/file/d/0B4gbHhYw7ejZUDdLQ0FfdzNYUGVocTdjUW5tczQ5LW9PeEZR/view?usp=sharing[/img]

I'm with Tim and Jay too. Sounds like the perfect solution.

Maybe you can source just those aisle posts from someone else. You're going to need plates that are longer than 16' for the plates too (for the scarfs). I would consider adding a bent, because your tie beam and joist sizes are going to be huge at ~16' on center.

I've never heard anything negative about queen post trusses. I much prefer them for simplicity in cutting and assembly over king posts.

Actually, the first design I proposed had one more bent for that reason actually. Left me with a 13 foot spacing roughly which was much easier. In fact everything was great about it, and was getting ready to send it on to the engineer, but then heard from the sawyer about the long aisle posts being too much. Proposed getting them from elsewhere, but it's not in their budget.

You can scarf posts as well.

I always tend to fall to "Occam's razor" when thinking about such constraints on a project between material resources (usually cost vs length thing 80% of the time) and what a client wants vs can afford.

So...in this case, we have isle post that are beyond the scope of the selected sawyer. That means either:

Chainsaw mill these posts from longer bolts (logs) yourself...

or

Employ a long structural splicing joint (aka scarf) that is well and properly "glued and clamped" with an accepted/approved structural adhesive like "PL Premium" or Epoxy. Employ the correct joint like:

kai-no-kuchitsugi (貝の口継) (Shell Mouth Joint or "clam shaped splice") This joint (kainokuchitsugi) is commonly used historically in Japan for major columns/posts without advises, and is probably the better choice of the two offered.

isukatsugi (いすか継) ( halved rabbeted (oblique) scarf joint or "stork's bill scarf") if employed for a post must be in one of the "housed forms," of the joint like, sumikiri isukatsugi (隅切いすか継.)

My 2¢ at this point...

PLEASE NOTE THAT THE "FUNNY NUMBERS" ARE THE KANJI CODE FOR THE NAMES IN JAPANESE IF ANYONE CARES TO DO A PROPER GOOGLE SEARCH...JUST CUT AND PASTE...

Hmmmm, so I think I'll push harder on getting some tall timbers from another source, but if that doesn't work, I may go back to the Dutch barn design and consider scarfing the posts. They're 10x10 by the way. Where would you put the scarf? My instinct would say about the anchor beam.

Jay, do you have any images of the scarfs you're referring to? I can't seem to figure out the Kanji code stuff....

Thanks again,
B

"貝の口継"

Just take the above numbers in quotes and paste them into a google search then hit the image button. That will lead you to everything you want and feel free to email me if you have more questions.

Regards,

j

OK, that's what I did, but I was expecting something more specific, but that's still helpful, thank you.
So any scarf work I've done has been with purlins or plates, and for repairing rotten post bottoms with little actual load. I guess I wasn't thinking of employing them in new construction, but I guess if it's considered acceptable, then it's just a little more work. The posts are 10x10, so there should be lots of meat there to work with. The one in this image, is one of the more common one I'm seeing, but it looks short.

http://userdisk.webry.biglobe.ne.jp/003/326/60/N000/000/001/123842267865816317879.jpg

B

If you "dig into" the info linked to the "kanji" you can even find video of many of them being cut (though much of it is in Japanese or even Korean.) These two cultures have a much larger array of "splicing joints" and applications for them than we probably find anywhere else in the world.

They (and I) even carve them in stone for the base of post where they form both the post bottom and the plinth as one unit. Her is a link to some examples:

https://www.pinterest.com/tosatomo/stone-joints/

Feel free to email or call...the project sounds exciting.

Regards,

j

Wow, that's amazing stuff. A scarf joint in stone....whoda thunk? Thanks for the link! I'm a furniture maker and I've seen some amazing Japanese joinery, not surprised it's similar with TF!

I'm excited about the project for a number of reasons. It will be my first TF project out of my new shop, and in NB where I'll be moving to. Nice to have a client before I even move there! Also, I've never done anything in "dutch style" before so that's cool, plus the clients are of Dutch ancestry and I've never seen anything like that in the area before....so neat on lots of levels.

I may well send you an email, but the nice thing about having the back and forth in the forum is that's all down for the record and people coming along after me can learn from it. "We're all in this together" as they say!

Thanks again for the pointers!

Cheers,

Brent

Cheers Brent, great connecting and do keep us all informed of your progress with this project...Sound very cool, and I am sure you will love cutting a "Dutch y" they are one of my favorite barn types.

Any thoughts on the best place to put the post scarf in the dutch barn? I was thinking above the anchor beam as it would leave the post solid up through both ties.

Hey Brent,

Yep that sound about right...

I would come up 100 mm above the top of the anchor beam "diminish haunch" or other housing and then go up another minimum of 800 mm for the splice length.

Regards,

j

If you're considering these splices, factor in the extra time to cut them. I am sure sourcing long timber would be a time and cost savings as well as a more sound structure. Any splice is not as strong as a splice. I could see splicing a couple or fixing for repair. To install all splices is going overboard. You can cut all the other joints on the post in the time it takes to make the two halfs of the splice, fit them and have them come out nicely. If you client has cost restraints you will we working for no return.

I agree completely Tim, was thinking along the same lines, thanks for the reinforcement though. Time to talk turkey.....

B

I agree Tim, yet here are some thoughts/observations from over the decades...

I think in this case getting longer timbers is probably the much better plane, as they really aren't overly long...Not like a 40 tie beam or an 80 rafter plate, both of which are hard to work on and transport effectively or fiscally ($) easy to logistically manage either.

It does always "seems" faster in short view of this game to have full stock timber...yet perhaps the big picture would reveal more?

When we step back and really consider big stuff above 8x8 (these I think Brent said are 10x10) there is something there to think about. When we have truly examined all the logistics of log acquisition, transport, human ergonomics of lifting, moving, rolling, etc. the aspects of "splicing" starts to reveal perhaps a better path, as a smaller timber size...sometimes...may well rule out over using larger stock, or at minimum it works out pretty even.

As for strength, these joints evolved over millenia to try and incorporate as much "regained" strength" as possible...yet...I do agree they, on there own, no mater how well executed are going to be of lesser strength than a full natural timber. I would like to, however, suggest a few observations to the contrary or alternative of this.

I think when we state things like that...again we are loosing perspective of the larger picture. If we don't cut any joints in a cant (ie timber) it is strong, yet we wouldn't have a timber frame without those joints we cut. Placing joinery of all types...including splices...in the logistically correct spots they need to be is the..."art"...we practice. So adding a well planned, laid-out, cut splice to a column/post isn't really that much more deleterious...overall...than any other joints per se that we must cut...

I would also close with a very important aspect of this recommendation thus left out...glue. When this is added back into the equation for a splicing joint, we can usually not only regain complete strength back, but often (and these joints are heavily tested and even have competitions around them in japan) end up with a timber that would fail outside the area of the now "cut and glued" joint, just as rope breaks outside the knot rather than at it...

One added incentive...If after all the tally is in and it reveals a cost that is about 50/50 either way...I say lets pay ourselves for cutting neat joints and using joinery to solve our timber framing challenges...not just getting the biggest sticks we can...

Just some additional food for thought...ultimately do what feels right to you and the client with blessing from history's lessons of past timber frames...

I hear what your saying, Jay and have no disagreement. I am expressing my view. I also have a mill at hand that is capable of cutting 70' My day hours are a mix of farm/lumber/framing mix and I get ancy sometimes when some aspect take from another. I try to be aware of how my time is dispersed.

Also, after 25+ years in the trade and I'm about to hit 50 I'm always looking for shortcuts but still retain the "art". More lodging of joist and long timber. Design buildings that work for us, and less we work for it.

No worries Tim...this is a common academic discussion among all us Timberwrights.

It is more a "view on a spectrum" than a "due this or do that," kind'a thing...which I bet we both agree on 100%

Someone with your tooling and skill sets would be working against logic (and maybe common sense) to not take full advantage of the kind of tool and knowledge resources you possess. That is also why I hinted at the "chainsaw" milling aspect (or even hewing) as many project job sites have large trees "on site" that could be fashioned into very long timbers...and...that is part of our craft also.

I really do like keeping as much work "in house" as possible for each of us as Timberwrights. You like me also have experience being our own logger and sawyer...which I wish this was still a more common practice as it was with the House, Barn and Timber wrights of days gone by...

I'm actually more prone to "go big" than just joint...but...I have the skills to hew/mill my way to get what I want...just like you do. Which is better than jointing...I agree...

I was originally thinking that the scarf in a post to make it taller would be best at the base of the post. I just thought that the top above any other joints may be where there is some stress that might not be the best location.
What would be wrong in putting a "post extension" on the bottom of the post and keeping the top in tact from top tenon down to post extension scarf?

Jim Rogers
PS. post scarf location maybe a question for an engineer to answer.

Usually when we see then at the bottom (the most common location as Jim has pointed out) it is either to replace an already standing frame post bottom where the it has been comprised in some fashion or it is planned from the beginning with a stone scarfed plinth as illustrated in the link I shared.

I think, in Brent case, the goal is not having to mill or handle a really large long post. This may not be perhaps such a challenge for some, while for others, both wight/size and transport/cost logistics are inhibitive. In this case, after considering also Tim's insight and from past experience, I would centralize the splice and probably make in a meter or perhaps longer, it must be reinforce with adhesive there by rendering the timber virtually whole and solid once again. I would most likely incorporate the through tenon of the "anchor beam to also lock and tighten the scarf. In that scenario, I believe we get the best of all worlds. Two shorter almost equal sized timbers, and good location that works in concert with the other timber joinery. It may perhaps even become somewhat invisible if cut using a version of the recommend kai-no-kuchitsugi (clam shaped splice.)

That, at least, would be my solution if I had to split the timber into smaller size for any reason. I have had this discussion with Ben years ago at Fire Tower PE and noted several more "approved" forms as just described while studying the Asian original forms. I do agree with Jim, that checking in with a PE is advisable if uncertain of ones skill sets in such advanced joinery placement, or at minimum discuss all pro/con with client as it affects cost.

Regards,

j

The problem I see with scarfing posts is that you don't want all of your posts to be scarfed. On my last Dutch barn restoration I scarfed five posts, and replaced the other five. This was the architects decision. Having available material length dictate your design is really tough. You may have to broaden your search for a different mill.

I think David, that much of this is perhaps a perspective on a very subjective continuum. Scanning back through every point made by each of us has its validity either in a give situation or from a given perspective.

When discussing "new work" it is vastly different in my mind and ethos from that of heritage conservation, restoration, or reconstruction. Here I tend to be a very "hard liner" following a strict ethic as set down by the likes of the Burra Convention, where "like for like" in means, methods, and materials" is a cardinal mandate of any heritage work, with regard to architecture/artifact restoration/reconstruction. Conservation efforts are different in the since that elements of modernity are often employ, even though all efforts are suppose to be made that these be reversible.

I think the concept of placing scarfs in multiple location in "vintage material" may have some merit as the necrotic elements of a vintage frame are all that typically requires the repare, so by that nature could/would be in multiple local. Brent's dictates are different than what would be reflected in a heritage Dutch Barn. Thus far the material logistic that Brent faces may be more of a challenge and constrictive.

Material do often dictate design and for this reason we see the fast range of different timber framing modalities between regions and cultures whether it is a Japanese Minka, Indian Kath Kuni, or some Pacific North West Tribal timber structure. Material and method dictum's are the norm in my view of this craft. Kind'a like the old adage the Amish I learn this craft from would say...

"...we plow with the horse we have...not the one we wish we had..."

My point about scarfing all the posts had nothing to with restoration. I only mentioned it as a basis for my experience as opposed to just someone with an internet connection and an opinion. We would have scarfed all of the posts to save the historic fabric, but that was deemed to be inadequate by the architect, Jack Sobon, and we decided to put five new purlin posts in to give the frame more strength.

I am aware that materials dictate design, but in this case the preferred design is in the North American range of English or Dutch construction, and they use a lot of longer timbers. I don't think I've seen a thread yet were you haven't tried to mash some other, usually Asian, framing "modality" into the mix.

First David, I don't "mash" anything into timber frames...especially historic vernacular restorations, as I suggested above in a very clear foundational ethos. If Brent's goal is a 100% authentic recreation of a Dutch Barn, then I am all for making the effort to replicated and match that known vernacular in every element of means, method, and material. I have absolutely nothing against such efforts at all...

Wherever someone, be it an Architect or Timberwright, (with good counsel from our PE I should hope) cares to place a scarf joint in a frame is by all means their pejorative, and right of creativity; especially if it had...as you say... "nothing to do with restoration."

I am not sure what the comment about "someone with an internet contention and opinion" has to do with this conversation and seemed rather a hurtful intent.. I think everyone commenting here is basing their comments on experiences. I would also suggest we all have valid opinions to share and internet connection...including you. Up to now it has been a friendly discourse of sharing those ideas...At leas I thought it was...??

So...if something isn't a full historic restoration or reproduction, I don't see the reason for suggesting stifling creativity. Contemporary frames can come in any (or the many) styles or flavors the originators care to put in them, and I think many of the contemporary forms are rather stunning. Especially when these forms respectfully and appropriately borrow from other vernacular.

Respectfully, just an alternate view.

Thanks very much all, I appreciate the time to post and I am soaking it all in. My preference would be to not scarf for all kinds of reasons we seem to all agree on. I am proposing a sort of middle ground to the clients that I hope will work. I am going to try to shorten the barn a little by flattening the roof and getting approval for some lower headroom upstairs. This will make the posts shorter and with that I am going to ask the sawer to commit to sourcing and sawing as many of the timbers as he can, with the objective of getting half of them. I will then source a few from my own connections as I can, and we'll scarf the rest. My hope is that of the 12 long posts required, only 4 will be scarfed and i will make sure I get paid for them! I probably distribute them evenly along the building, but my intuition says I shouldn't put them on the ends, having them somewhere in the middle 8 posts would make more sense.

On another note, what separation between the anchor beam mortise and the lower tie mortise is typically used? I have seen lots of pics, but no measurements.

Thanks again all,

Brent

Hi Brent,

I was just in two vintage examples from 1780 to 1820 in up state New York in March this year before going to Texas for a Barn repare. Those two examples and other examples I have been acquaintance with probably average (subjective guess) anywhere from 250 mm (~10") to 400 mm (~16".) I do believe there is some recorded data out there, I will see if I can find it, unless someone can put there hands on it sooner for you...

Regards,

j

Excellent, thank you again! I think there's another way I can tighten things up a bit.

B

Jay, the comment about the internet connection was not directed at you. I was simply trying to bring some of my background into the picture as a way to add relevance to my post as compared to a lot of people that have an opinion on something they have no first hand knowledge of, as is often the case on the internet.

timberframe, what are you calling the lower tie? Is it the girt that connect each purlin post together? Or are you talking about a loft joist or outshot tie, as we call them, that goes from the purlin post to a wall post?


Here is a short video of one of the Dutch barns I restored:

https://youtu.be/6mcIrlYBua8

Sorry Dave, my terminology must not be right, I meant the two girts on either side of the anchor and a bit lower than them. So I think the latter of your two. Good to know the proper terminology, thanks.

I will check out your video!

Brent

Hi Brent,

I knew what you meant by "lower tie mortise." There are just so many freaking terms and many even specific to a certain region or county, that it can be difficult at times to get them all sorted. I have floating around here someplace the "actual" dutch terminology for these peaces and I believe it translates into "central isle post" and "eave posts" for these bent assemblies though "purlin post" and "eave post" have become standard nomenclature I here used today as Dave has suggested. If I can find that document (or someone else has a copy) please do share it.

Hello Dave S.,

I appreciate your validation, and remembered that video...(excellent model by the way)...wish that was still the practice, but CAD has won out for speed and dexterity for most of us...They do still do these for the more prepackages frames everywhere I know timber framing to still be active. Nice to see one like that. Do you have a video of the finished frame?

I apologize if I mistook your meaning and intention. The "teacher" in me is very keen to listen to everyone's views, even if it is only based on a little experience. I have learned as much from my students over the years as I have the experienced folks sharing. The "new to the craft" often have the most insightful questions and perspectives and their mind are fresh to all this stuff....

Regards,

j

I have to ask how long these to long post are..... 20'? With 6 bents and all splices(although there now seem fewer) that would be 12 post, each post having two halves for 24 pieces. Depending on the skill and tooling each could take 2-5 hours to cut. In splicing alone I can see 6-10,000 dollars in additional labor. It would also require more board feet of timber,as the short piece would require the length of the splice extra plus the dropped ends of each piece. This is decent enough justification to use long timber, let alone the structural issue it brings. I would throw some iron at it and bolt them if it came down to splices. A glued joint is going to require even more time to execute, you will need exceptional tooling and/or patients.

Also, with these splices think about the raising and how the slip of a bent would could effect this splice? Getting a bent into the air is not always a pleasant thing.

Source the correct length timber and have it shipped in.

Glad to hear J. Sobon had issues with too many splices in such a frame, Dave.

Both of the Dutch barns I restored are in storage. One is for sale the other has been sold, but the owner is on about year 5 of a 20+ million dollar office building renovation. I did models of both barns. They are a great tool to show people proportions and possibilities for the frame.

I agree, that many scarfs would be a little crazy and blow the budget I'm sure.

Well I've managed to shrink the barn by a couple of feet. Still a good pitch, and the headroom under the outshot tie is 7 feet, and the anchor almost 9' and the headroom under the upper tie in the upstairs is 6.5' but of course there's a lot more headroom between the bents. If I can get the ok on these clearances (and make sure they remember the braces too!) this would drop the big posts to 18' including tenons....which I think ought to be ok. That sawyer has already sawed me a whole bunch of 8x10 at 17.5' so....

Thanks all, I'll keep ya posted.
B

Hi folks, just thought I'd give you a little update. I kept leaning on the clients and as it turns out, they're going to get a large circular mill to cant the large timbers to a maximum of 24x24 at the butt, so they can be used with the mill chosen. This means I should be able to get the full length timbers for the aisle posts! I'll keep y'all posted.

B

hello everyone tonight

Well just had to add my 2 cents worth to this great discussion--splicing posts

Personally where to place a splice in my perspective is near the bottom of the post, and I say this from visual experience

Our 1865 Mulay Saw mill at UCV had most of it main vertical timbers spliced at their bottoms, and this was due to rot that happened on its original site where it stood for about 100 years

scarfs of about 4 feet were manufactured from old timber of original size and wood type and age--these scarfs were nothing special, just a half lap joint, and held together with 5-- 2" wood oak pins

This mill was restored under a leading restoration architect Mr Peter Stokes at that time, hired by the Ontario Government to oversee all aspects of the reconstruction of the vintage buildings on site

This was in 1961--this was 54 years ago now, and the splices have never moved or needed any attention, there was no glue, or steel added to the splices either

Now in the Gristmill restoration in 84, all the first floor horizontal timbers, had to be hollowed out and flat plates of steel glued in, this was to meet modern PE standards, even though the timbers were in excellent shape and had held countless tons of wheat, oats, barley over its years as a working mill

I did also dismantle a 100 foot barn that had 20foot bays, and the upper plate was spliced at 20 foot intervals right over the tenant on the upper end of the post at that location, this barn had also never moved was straight and graceful when stripped of its outer cladding

I had no idea that you could include that many splices and get away with it--as a final thought these upper late plates were basswood, which around here is a very soft wood, without a visible grain

NH