Author Topic: "Timber Frame" with site-built beams  (Read 7381 times)

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Offline Pallas

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"Timber Frame" with site-built beams
« on: September 21, 2015, 02:31:40 PM »
Hello all,

I wanted to run this question by the forum, in case I'm missing something obvious. In my search for plans/building methods, I came across the FirstDay Cottage kits, and while I decided they weren't for me (their standard plans are a bit restrictive), I really, really like the look of the quasi-timber frames and how accessible these seem to be by just building beams on-site:





My question: I've been looking just about everywhere for instructions on how to properly build these beams. What appeals to me about this method is that it looks like the sandwich method creates ready-made joinery (appears to be tongue and fork) for a frame that can be easily fit together. So, aside from bypassing expensive solid beams, there's the added benefit of not having to carve out tenons, etc.

I understand this is the signature building style of FirstDay, but I would assume this user-friendly framing method would have been picked up by other owner builders by now... but I can't find anything. The best instructions I've seen have been in Alex Wade's books (who worked alongside FirstDay's founder in the 80s), but these are incomplete. Can anyone out there shine some light on the matter?? A few universal rules is all I'm looking for - then I can use traditional post and beam plans and just substitute the solid beams for built-up ones.

Offline Don_P

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Re: "Timber Frame" with site-built beams
« Reply #1 on: September 21, 2015, 04:16:28 PM »
There is some info on built up columns in Wood Structural Design Data, free download from awc.org. They also publish the code referenced NDS, there is a free view only download and the supplement to design values that accompanies it for wood strength data. If you go into the supplement you'll notice that built up beams of dimensional lumber will be considerably stronger in bending than solid sawn timbers. It is easier to see the defects and they are randomly dispersed in a built up beam. Yes it is a good way to create a post and beam building.

Offline Adam Roby

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Re: "Timber Frame" with site-built beams
« Reply #2 on: September 22, 2015, 01:10:56 PM »
This is the approach I was considering as well, at least for the structural elements.
The advantage was that the posts were continuous from the ground to the roof, and gave it a lot of diagonal bracing with the walls.

http://countryplans.com/smf/index.php?topic=13596.msg177930#msg177930

Not that I have actually built anything like this, but that may be one of the next steps.

Offline new land owner

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Re: "Timber Frame" with site-built beams
« Reply #3 on: September 22, 2015, 02:22:57 PM »
I did something similar with my screen house. I used 2 x 6 material and ripped the boards so I ended up with a "6 x 6" post and beam.

http://countryplans.com/smf/index.php?topic=6670.0

Offline Pallas

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Re: "Timber Frame" with site-built beams
« Reply #4 on: September 25, 2015, 06:09:24 AM »
Wow! This is great, and exactly what I was talking about, thanks so much for the links and details - Adam Roby, definitely keep us updated if you decide to use this method. And that cabin is super cool/beautiful New Land Owner. That AWC link led me down a good rabbit hole of engineered wood standards and will keep me busy for a while.

I wonder why this method isn't used or seen more often, though - there's such a lack of information online (aside from here). I think I can figure out enough on my own about loads and spans from the code resources. However, what I'm really stuck on is the joinery, as one of the big draws here is the ability to assemble notches and tenons from the wood pieces. Like I mentioned, Alex Wade's books are the best resource I've found so far (I'm copying a very small snippet here for illustrative purposes, but I recommend everyone buy his books, as they've been great resources)




I haven't seen anything else like this elsewhere though, and I wonder how you all were able to figure out exactly how to join the beams in a structurally sound way. My plan is to purchase some traditional timber frame plans and modify them with built up members - but once the plans start using traditional joinery, I'm stuck on how this translates. Any ideas or resources I'm missing?

Offline Don_P

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Re: "Timber Frame" with site-built beams
« Reply #5 on: September 25, 2015, 02:50:11 PM »
You are stepping outside of the prescriptive portion of the code and into methods that call for engineering. The code then references the NDS for the equations and engineering. Basically the rules don't change just the methods have. The same structural requirements apply. You are collecting loads to fewer discrete points rather than distributing the loads uniformly, but, the same restrictions on maximum wood stress and allowable deflection apply. The engineering looks into things like localized crushing around post and beam connections due to that concentrated loading. If you would like some help with that part start sketching and asking questions.

Offline Pallas

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Re: "Timber Frame" with site-built beams
« Reply #6 on: September 28, 2015, 08:44:42 AM »
Thanks for the additional insight Don. I know this method will require an Engineer Stamp by NY Code, and my hope would be to come up with a build-up method that would satisfy NDS standards and an engineer can just review and confirm (does this sound like feasible or am I biting off more than I can chew?).

I'll work on those drawings for feedback. Meanwhile what I am currently working from are from the Alex Wade book. I don't think that image was pasted correctly, so here is a link to it instead:

https://www.dropbox.com/s/jekskiz5pg48rph/Alex%20Wade.JPG?dl=0

Any thoughts on that type of lapping/joinery?

Offline Don_P

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Re: "Timber Frame" with site-built beams
« Reply #7 on: September 28, 2015, 05:19:02 PM »
I think that is a good idea. The more you know...

In the pic, he's trying to intersect 2 beams at a 90 degree angle onto a post at the same elevation. I don't know the details around this case. First look at whether you need to do that. Often you can design around that situation with a little thought.

Then, in my mind and that is all it is, I would design the frames as bents. Flat 2 dimensional slices through the building. Then tip those up and insert horizontal girts between those bents. The built up girts fit into concealed flange joist hangers attached to the bent posts. So what I'm proposing is lapping in 2 dimensional bents and metal connecting the beams between bents. Sheathing braces the structure from racking.

One thing to keep in mind is the strength axis of your build up. It is strongest in the depth direction of the 2x pieces. Let the sheathing support the weak axis, nailed to the edges of the plies.

Somewhere are the papers... there, google "Bonhoff, nail laminated posts". EP559 is the official document, (EP-engineering practice) the others are research and articles it looks like.

Offline Don_P

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Re: "Timber Frame" with site-built beams
« Reply #8 on: September 28, 2015, 05:55:52 PM »
Basically this style is what I was describing
Flat 2 dimensional bents that are tipped up, in your case these are built up assemblies;
 



Then girts, purlins, brace panels, etc are bolted in between. These actually were built up assemblies, 2 ply of 4x material


Offline Pallas

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Re: "Timber Frame" with site-built beams
« Reply #9 on: October 01, 2015, 01:52:10 PM »
Don, all of that looks really great! It answered questions I didn't know I had yet - thanks so much for taking the time to explain. As I'm doing more research for drawings, I think I'm finding so disadvantages to this method. You touched on it in your explanation, that sheathing would act to brace against racking - this essentially means that the board siding/wall is a structural necessity, unlike true post and beam (am I correct here?). This would also mean that if I wanted drywall, I would have to put it over these boards instead of just the panels strapped by foam boards. This appears to be the same way FirsdDay does it, though they don't even use girts between the bents and rely wholly on the boards:

http://2.bp.blogspot.com/_9-9El-y_YPQ/R8C_H13QiEI/AAAAAAAAARY/N1yTitubhPM/s1600-h/DSC03580.JPG

Another thing I saw was the lack of "great rooms" in these models, and I'm wondering if there's something about the limited connections that prevents open space in the designs, or if there would be a way to design around it like you mentioned:

https://www.dropbox.com/s/k70hd2ztomoloee/FD%20Great%20Room.jpg?dl=0

Now my MAIN question is (it took me a while to get here, sorry): this is making me wonder if I should incorporate true timbers in my design for more traditional post and beam allowances. I was convinced that the built up beams would be a cheaper alternative, but after looking at sawmills in a 100 mile radius (not many sawmills nearby) I found the price per board foot for rough cut lumber to be only a few cents more than dimensional lumber quoted at local Lowes (for a very quick number crunch). I know shipping would be a factor, after taking into consideration the nails/brackets of site-built beams, maybe the price evens out?

Sorry to throw a curve ball in there, but I was a bit disappointed that the built-up method wasn't as transferable to timber as I thought. Any thoughts? 

 

Offline Don_P

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Re: "Timber Frame" with site-built beams
« Reply #10 on: October 01, 2015, 04:28:28 PM »
A timberframe also develops it's lateral bracing through the sheathing most of the time. Nowadays it is often through the use of SIPs to sheath and insulate the frame. I don't see a dissimilarity there... the methods used can lean more towards traditional framing if that is desired. Post and beam can go either way, it is easier to create strong moment resisting joints using steel in the connections.

Typically to allow for drywall on a timberframe, strips of 5/8 plywood that are narrower than the frame width are nailed on that face of the frame. The sheathing is nailed or screwed through that spacer. Then on the interior, after it is dried in, drywall can be slipped into those grooves that have been created between frame and sheathing. This can be done with either method.

I enjoy working in big timbers more. I would think working in solid sawn would be faster than built up. I guess tooling and species can make a big difference.  Large timbers will check as they dry. 5x5 and larger timbers fall under a different, lower, set of design strength values. Built up timbers begin with higher design values and get a 15% bump from those values for being built up and distributing defects... members can be smaller usually. A solid sawn timber needs to be larger for the same span and load, I like big wood.  Joints will move more in a large timber... although the joinery on a 1st day isn't beautiful. The radiused edges on standard dimensional lumber and the exposed nails is something to consider there as well. The species selection sure opens up at the sawmill. I prefer to work with dry material, what comes from the mill will be green and big. Pine and hemlock will dry faster than most of the hardwoods.

Either can have open plans... designers design from what they know. Some know more, some less. Then again some are not bounded by much atall. I can sit on any of about 4 sides of this conversation.

Offline Pallas

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Re: "Timber Frame" with site-built beams
« Reply #11 on: October 04, 2015, 04:43:13 PM »
Don, thank you for sharing your extensive experience on here! It’s so good to have people who clearly know what they’re doing for us novices to learn from

My end goal is to have the timber frame look –  a 1.5 floor house with the second floor area looking over a great room below. I was drawn to the FirsDay system for the assumed affordability of dimensional lumber over solid beams, and ability to build up the beams off-site on weeknights and transport on the weekends. I ordered the TF Guild workbook “14 Small Timber Frames” to see if I could modify some of these with built-up lumber and learn a bit on a smaller scale.

However, you make some really good points about the aesthetics and the exposed. I’m not a traditionalist, but this, added to the extra headache of having to modify for built up beams and then get an engineer may tip the scale. Here is the drawing I was working with so far. The top girts are two versions of how these could be fitted to the column:



If I went the route of solid beams, I would get rough cut-pine from a saw mill since they’re local and the lowest price. I’d be willing to take a timber framing workshop (at Heartwood or the Shelter Institute) and do traditional (simple) joints instead of Post and Beam brackets , since I think it would be a good investment for the general framing education (plus, the bracket/sockets would almost cost the same as a framing class for traditional joinery). Then, I would purchase plans and notch my own beams.

I’m at the early learning stage right now, though, so I don’t know if any of these plans sound feasible or friendly to a modest budget. Is it even realistic to think one could build a timber frame at a lower cost?

Offline Don_P

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Re: "Timber Frame" with site-built beams
« Reply #12 on: October 04, 2015, 06:42:54 PM »
I think that stick frame is the lowest cost. Timberframe or something with exposed beams is appealing and can be done affordably if you provide the sweat. Personally I think stick framed walls with timberframe roof elements is a good compromise. I would expect to need an engineer for either method.

The pines vary quite a bit. Mentioning those schools makes me think you are talking about eastern white pine, Which is what my shop in the pictures is built of. It is one of the most stable and low shrinkage pines but is fairly weak and needs to be carefully graded.

Of the two girts I'd go with the lesser post damage of the upper one. With a 3 ply buildup on the girt the middle ply could be inserted in a mortise in the post. But I think I'd use metal connectors for those. I would infill the beam ply at the brace layer for aesthetics, to lock the brace and to stiffen the beam. For that matter I'd probably build up the brace.

Offline Pallas

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Re: "Timber Frame" with site-built beams
« Reply #13 on: October 05, 2015, 05:13:48 PM »
Thanks again for your input Don. I'm honestly really torn between: 1) trying to mimic the FirstDay built-up system, 2) getting a FirstDay all out and save myself the headache, and 3) a traditional timber frame.

I understand that the FirstDay prices also include the guidance/coordination that come with having the company behind you and the priority is actually finishing a house build which I know is a risk many would-be builders face. However, I don't think the pricing reflects the materials and much of the value-add is the system (which may be very worth it to many people)

It seems like every day new information pulls me in a different direction. I got excited seeing some rough-cut prices, but then thought about the effort of processing/planing/joint-making green beams and for a beginner it sounds overwhelming - and there would still be a whole house to build! Timber frame kits are very expensive, but I did find what appears to be the most affordable one out there: (http://distinctivetimberbuildingkits.com/) has anyone heard of them? The pricing seems to be only about 6-7k more than the materials would cost (assuming about 10,000 board feet for a full frame) and can be put together in a few days. This would certainly be a good way to start a house project. Does it look affordable or am I just inexperienced? I wonder if I would be able to contract out joinery/planing of green beams for a lower price...

Offline Don_P

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Re: "Timber Frame" with site-built beams
« Reply #14 on: October 05, 2015, 06:38:32 PM »
Interesting, they look to be pretty basic,mostly miter and oly screws. Nice alternating stair at pic 34 in their gallery. They are doing a few things that make me think there isn't an engineer involved. That may be up to you if needed, which is probably the case with anything you bring in from out of state. The prices do appear to be good at a glance. Hmm, cutting out a small dutch frame for cost + 6-7k, I could see churning out 4 or 6 a year   :).


Offline Pallas

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Re: "Timber Frame" with site-built beams
« Reply #15 on: October 05, 2015, 06:58:45 PM »
Haha, it's a good business to be in if you've got the time and experience!

Honestly, all of those timber frame kits out there seem targeted to those looking for luxury cabin/lake houses, and not the owner-builder. I would think the cutting/notching business could really have a market, no? I think it would be a win-win for everyone involved. A set of plans + Decent $/bf on rough beams + contracted planing and cutting work = a decently priced timber frame I would seriously consider!

Offline Pallas

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Re: "Timber Frame" with site-built beams
« Reply #16 on: October 06, 2015, 10:59:43 AM »
So I spoke to the guy who does the Timber frame kits today - really nice guy and very willing to work with designs. Turns out they use Timberlok screws for the connectors - no brackets or other metal connectors. A quick search online only shows their use in rafters and small applications, so I don't know how they would hold up on a whole house frame and importantly, how the NY code or engineer would look at them.

Anybody ever use Timberlok or similar nails for large post and beam applications?

Offline Don_P

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Re: "Timber Frame" with site-built beams
« Reply #17 on: October 06, 2015, 04:34:53 PM »
 I have used them aplenty. I'm not sure that I would put them to all the uses they have. For something similar but a stronger connection in the more heavily loaded joints take a look at these,
http://www.timberlinx.com/
 

Offline alexwade

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Re: "Timber Frame" with site-built beams
« Reply #18 on: December 11, 2018, 10:39:36 PM »
I know this is an old topic, but it's the most recent one referring to myself, Alex Wade.  I designed my first house in 1959 using the framing system shown in the sketch.  I'm 82 but still designing if anyone wants to contact me.
Alex Wade, Author of several DIY housing books

Offline akwoodchuck

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Re: "Timber Frame" with site-built beams
« Reply #19 on: December 12, 2018, 12:57:25 PM »
I know this is an old topic, but it's the most recent one referring to myself, Alex Wade.  I designed my first house in 1959 using the framing system shown in the sketch.  I'm 82 but still designing if anyone wants to contact me.
Alex Wade, Author of several DIY housing books

Hi Alex! We have several of your design books in our local library, I've thumbed em pretty well over the years....never been a fan of pole foundations, but beautiful house designs!  [cool]
"The lyf so short, the craft so long to lerne."

 

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