• Post Reply Bookmark Topic Watch Topic
  • New Topic

laminating 2x4s for a small timber frame?  RSS feed

 
Gilbert Fritz
pollinator
Posts: 1340
Location: Denver, CO
25
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
I want to build a small timber frame structure, 8'x15'. I have stacks of salvaged 2x4s but no heavy posts. Could I fabricated posts and beams from the 2x4s? I'd assume that I would use bolts and glue.

I realize this would be weaker then a solid post or beam, but could I get around this by oversizing them?

Also, could I preform joinery by leaving out chunks of 2x4?

If this wouldn't work for beams, would it at least work for posts and sill plates?
 
Travis Johnson
pollinator
Posts: 1368
149
books cat chicken duck rabbit transportation trees woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Actually you have that backwards, laminated beams are actually stronger then single cut beams and posts, just use plenty of spikes when you put them together. There is no real need for bolts and glue, though you could include them if you wanted too. The strength comes in redundancy, and a lack of weak points across the whole post or beam as what happens in single cut beams. Kind of like how 1/2 inch plywood is stronger then a 1/2 inch board.

What you propose is possible, and I have seen it done. In fact my local Fast Squad built a building as you propose but used pressure treated for the posts entering the ground. They laminated it with full pressure treated wood in the ground, then above ground, started splicing in regular wood since they staggered the joints. It is hard to describe, but I am sure you can picture it. If you dislike pressure treated due to the chemicals, just substitute cedar framing, or another rot resistant wood that is all natural for the in-ground parts of your posts and sills.

I am not sure it would look quite like a real timber frame (my home is timber framed), but maybe by cleaning up the edges with a power planer, it would be close. I would think they would inevitably be out of alignment when you put them together, but a few passes with a power planer would make them smooth again.

One trick you can employ is using 1/2 inch plywood or oriented strand board (OSB) as a spacer. Lets say you are making a connection from beam to 2x4 on edge. Nailing (2) 2x4's together, which are really on 1-1/2" by 3-1/2" wide will only give you a 3"x 3-1/2" beam. To make it truly square, just add a 1/2" spacer of plywood in between the (2) 2 x 4's. This will give you a 3-1/2" x 3-1/2" beam. This also strengthens the beam as you have alternating layers of fiber and glue. It is just a pain to cut strips of plywood in 3/-1/2" strips to do so.
 
chip sanft
pollinator
Posts: 427
Location: 18 acres & heart in zone 4 (central MN). Current abode: Knoxville (zone 6 /7)
33
bike books dog urban
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
By glue I assume you mean construction adhesive -- cheaper, quicker, and stronger. Nails will work just fine to hold the 2"x4"s together and be quicker than bolts. The resulting bond, according to professional carpenter / former neighbor, will be extremely strong after the adhesive cures.
 
Joseph Lofthouse
garden master
Posts: 2616
Location: Cache Valley, zone 4b, Irrigated, 9" rain in badlands.
507
bee chicken food preservation fungi greening the desert
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Gilbert Fritz wrote:I want to build a small timber frame structure, 8'x15'. I have stacks of salvaged 2x4s but no heavy posts. Could I fabricated posts and beams from the 2x4s? 


In conventional housing, corner posts, door posts, and window posts are formed from 2X4 wood. They are not typically glued, just nailed together.

A 2x4 doesn't seem structurally sound enough to me to be spanning 15 feet as a beam. Beams for that size span are typically 6 to 8 inches or more tall, depending on load.
 
Glenn Herbert
gardener
Posts: 2256
Location: Upstate NY, zone 5
79
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
An 8 x 15 frame would take more wood for the long beams than if you made intermediate posts (two 7 1/2 x 8 sections). However, it would only require four post holes instead of six. You can make tradeoffs as desired.

I would laminate at least four 2x4 layers for the long beams, and the bottom layer needs to have no joints in the middle half. 3 1/2', 8', 3 1/2', make the middle section as much longer than that as you can. Stagger all joints in different layers, of course. I would recommend Titebond II wood glue or equivalent rather than construction adhesive for actually laminating timbers. Spread properly and clamped or nailed thoroughly, it will become just about monolithic.

What sort of sheathing and insulation are you considering? If a loose fill type of insulation, you will need a cavity wall and there is then no point to timber framing such a small structure.

If you can find rot-resistant wood like black locust, that would be the ideal base for posts. You could either build the locust into the posts by trimming and lapping, or make the in-ground posts locust and set the frame on top of them. You would then need to depend on the framing geometry for stiffness rather than the post bases. This is no big deal, just use diagonal braces where needed.
 
Roberto pokachinni
pollinator
Posts: 1428
Location: Fraser Headwaters, B.C., Zone3, Latitude 53N, Altitude 2750', Boreal/Temperate Rainforest-transition
100
bike books food preservation forest garden fungi hugelkultur solar trees woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
As has been mentioned, building posts and beams out of laminated 2X4s can easily be done, no glue necessary, but lots of spikes joining your boards.  The only caveat to that is that the boards that you are laminating have to have some length to them to start with so that they build strength together.  Laminating a bunch of two foot pieces, for instance, is not going to make a very strong beam, but doing the same with 4 to 8 foot pieces involved would be extremely strong.  If you want to go the timber frame route, then you can figure out your joints utilizing small waste ends of 2X4 ahead of time, and then when you are fabricating your posts and beams you can re-create these joints that you have trialled with the bits.  It might be easier to build post and beam without proper timber frame style joinery though.  Overbuild the strength of your posts and beams, making sure that you are laminating over the gaps with enough wood that you have no conceivable bending between your small 2X4 pieces (hence the longer pieces as opposed to shorter), and you will make a very strong structure with as large and thick of beams as you want to make. 

on a slight aside: I have seen an entire cabin built of stacked nailed lumber with waste cut ends of 2X4s from a mill that were attained for free; in this case no posts or beams were needed.  A nice hexagon cabin was built.       
 
Larry Bock
Posts: 155
8
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hello, I built my own LAMs for the king I beam trusses for my future camp. All last spring all I did was spread glue and clamped 2x8s together. In between the two I put a strip of 3/4 plywood. The longest span is 20'. I can place each end on a cinder block and two grown men can stand in the middle with very little flex. They came out super strong. The one thing I did not count on was how much glue I needed and how much the glue cost. At $26 a gallon x 6 gallons, it was no laughing matter. If you do have to do some splicing together, cut the ends on a 45 degree angle. Larry
 
James Freyr
pollinator
Posts: 440
Location: Middle Tennessee
50
books cat chicken food preservation cooking toxin-ectomy trees
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
May I suggest using plywood instead of OSB for making your laminate beams. Traditional plywood has higher tensile strength and shear strength and will structurally perform better bearing load on a span. I think you could stack two 2x4's on top of each other staggering the butt ends for a total of 7 inches tall on both sides of some plywood and create some beams that way. Those may not pass city building codes, but may function well.
 
Travis Johnson
pollinator
Posts: 1368
149
books cat chicken duck rabbit transportation trees woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Going in a totally different direction...

Have you ever considered just making real beams by hand-cutting them out of logs? It is really easy to do. That is what I did in my house and my longest beam was 16 feet long. The others were 12 feet and the posts were 8 feet. All I used was a chainsaw and axe so you would not need a special tool. I am not sure how long it took me to make each beam, but it was not long, from stump to beam maybe 4 hours?

If you are interested in this I will explain in detail how its done, just let me know. Again it really is easy.

If you do not have logs to do this with you could probably find someone. A firewood dealer would be a good start, I am sure they could get some softwood logs for you. These here are Spruce.

DSCN3929.JPG
[Thumbnail for DSCN3929.JPG]
 
Roberto pokachinni
pollinator
Posts: 1428
Location: Fraser Headwaters, B.C., Zone3, Latitude 53N, Altitude 2750', Boreal/Temperate Rainforest-transition
100
bike books food preservation forest garden fungi hugelkultur solar trees woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
There are specifications in the B.C. provincial building codes for making laminate beams.  All of these include plywood. 
 
Gilbert Fritz
pollinator
Posts: 1340
Location: Denver, CO
25
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Thanks for the answers everyone!

Somebody asked earlier about why I'm interested in timber framing instead of stick framing. The structure will serve as a greenhouse and will be fitted with a wide array of salvaged glass in many different shapes, thus I though it would be an advantage to have all the structure in the corners.

I assume outdoor timbers would be at greater risk of delaminating if done this way? I'd like to build some arbors and other structures without a roof.

Travis, I would be interested in hearing more about cutting timbers.
 
Roberto pokachinni
pollinator
Posts: 1428
Location: Fraser Headwaters, B.C., Zone3, Latitude 53N, Altitude 2750', Boreal/Temperate Rainforest-transition
100
bike books food preservation forest garden fungi hugelkultur solar trees woodworking
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Spike your nails at alternating angles and you will likely not have much issue with delamination, indoor or outdoor.  The only issue with lamination, without glue and using it outdoors is that there is more slots for fungi and moisture to collect.
 
I'm THIS CLOSE to ruling the world! Right after reading this tiny ad:
Thread Boost feature
https://permies.com/wiki/61482/Thread-Boost-feature
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!