I am a cabinet maker working on my first timber framed project. I made my fare share of pinned mortise and tenon joints over the years, but with the holding power of modern glue, the pins are effectively decoration.
So why isn't glue used in modern timber framing? would it not just provide additional strength to a joint?
Large timber dries and distorts greatly in a variety of manners depending on where it was sawn out of the log in a three dimensional fashion. Surfaces not only change in width but surfaces curl, angles change, checks open and spread and adjacent timbers grain cross with the grain moving in different directions and amount. Glue may have some elastic quality but the thin layer of glue will not cope with the far greater movement of the wood.
The other way to look at it what would be the benefits of using glue? A timber frame is perfectly fine without glue and glue would add many drawbacks. As a cabinet maker you would understand how difficult it would be to raise a frame without glue joints drying too quickly. Raising a frame can take a day or more and in that time things often need moved and torqued or in some cases a bit of rework. And pegs would still be needed to make tight joints. Glue would add cost, time, and add more difficulty in disassembling and repairs down the line.
:D
That makes allot of sense. I have scrambled around the shop more than a few times on a complicated glue up, I can't imagine pulling it off on a larger timber project.
From woodworking you would know that large cross grain glue-ups are a bad idea. A couple of inches on a mortise joint in furniture is fine because the glue will flex enough to allow for that. But the joins in a timber frame might be mortises with 8" or more of cross grain. Now a big mortise joint, with a peg or two holding things secure, allows for some drying and seasonal movement. Without your stress of a cross grain glue-up.
Only place I can see a use is laminated beams, which isn't really traditional timber framing. But it's commonly used in modern wooden building construction, even on quite large multi-story buildings.
Technically there is no reason you couldn't adapt timber frame principles to use prefabricated laminated components, but you would still want to put them together with pegs or bolts.
Also...timberframing is done with green wood. You don't use glue on green wood because it is still shrinking and moving. Pegs have worked well for 2000+ years...that's why the craft still uses them.