Hello fellow timber framing enthusiast! I was wondering if anyone had any insight on choosing between green and dried lumber for constructing a timber frame? I will be using tamarack for the posts and beams. I was told to use it green to prevent major checking and twisting? makes sense to me, but was still wondering if there are any draw backs to this.
I typically frame green, unless I am using reclaimed wood, or repairing old wood. Wood is going to twist and check, there isn't much you can do about that other than to RFKD it, then surface all four sides. A timber is squarest when it is freshly sawn. That is the best time to layout and cut your joinery. It can sit after that, and most species will do ok drying a little bit before the raising. Some won't, they will want to move and check, making adjustments necessary at raising. In some instances, you will have to replace the timber.
Thank you for the reply Dave. By RFKD, I assumed you meant radio frequency kiln dried? In my case I will be cutting the lumber myself, so RFKD-ing the wood( can I say that?lol) is out of the question for the moment. So, basically if I do all the cuts and assembles the frame right away, I should be fine? also, is there an optimal time-frame from the time you cut the tree up to assembling the timber frame?
Sylvain
Ideally you would move along as fast as possible. I don't know the drying characteristics of larch, having only worked one piece of it. Softwoods will behave better for long term storage than hardwoods. I put up a frame in November 2011 that had been in storage just over two years and it was fine. It was all white pine. There are some white oak floor joists in storage for a restoration I did that opened up over 2" through the peg hole. They were half log joists, so there was a lot of stress in them.
Yes, RFKD is radio frequency kiln drying, the only way I've heard of to dry large timbers. It's not relevant to my framing style.
I believe there a mention of the timing (yearly and months) in Jack Sobon's "Build a Classic Timber Framed House" where he says something like cut your trees down in the fall, cut your joints over the winter, erect the frame in early spring.
Take the summer to roof and enclose the frame and then by the next fall when the "heat" of the house heating system "comes on" your timbers have stood air drying for a while.
This will reduce the amount of "fast drying" that can happen and it will hopefully reduce some of the wild checking and keep your frame more stable.
People have told stories about being in bed at night when the heat is on and hear a crack or check go off and it sounds like a "shot gun" blast in the house, until the frame drys out.
If timbers are stored properly then they should be able to "sit" for a while, during the time you're cutting all your joints.
Jim Rogers
Thanks again for the info Dave and Jim!! what about the pegs? should they be dried or green? It would seem green pegs would shrink and cause instabilities in the joints.
I make my pegs out of air dried oak stock.
I take boards and rip them to squares, inspect the grain for slope and if it has a lot I chuck it out.
If it is straight then I shave them into pegs.
I don't put them in any bucket of water like others do, I leave them dry.
After you have cut your joints and test fit each one and then do the final assembly your pegs should be pretty dry.
Being that dry when you pound them into fairly green timbers they will absorb some moisture and swell up. You won't be able to drive them out if you make a mistake so be sure when you drive them in you're right.
Good luck with your project.
Jim Rogers
Ditto on Jim's advice as per timing! I would not recommend letting Larch sit around un-assembled too long. It will twist on you. Design your joinery to resist the twist if you can. Cut it in winter and assemble in the spring if you can. Keep the timbers out of the sun too. They will go crazy if piled up in the sun!
Thanks for all the info guys, definitely appreciated! I have been reading some more on Tamarack and it seems not all grow with spiral grain( which is apperently the main cause of twisting?). If you pick trees with straight grain, the twisting is kept to a minimum. I checked a few bigger ones today and they all had really straight grain and grew straightl like a board. Now hopefully they`ll stay the same after milling :/.
One thing that wasn't mentioned was sealing the end grain with Anchor-seal. That will stop moisture from quick escaping the ends of the timber. If left unsealed, the timber will dry unevenly- that is the ends will dry out more quickly than the middle and can check or move. Sealing the end grain forces all drying to occur out the sides of the timber, which will happen more slowly and more evenly and tends to reduce checking. You can also seal the ends of the log, but get the log off the ground so there is some airflow around it and don't leave them out in the sun, which would force accelerated uneven drying. Keep in the shade where there is air circulation to keep them drying slowly and evenly. Do this with an oak log and many others, and when you go to saw it, you can still consider it a green log. They don't really dry out on the inside. Once cut into lumber or timbers, They will dry out over the course of 1 to several years. The smaller they are the quickly they dry.
I will definitely seal them with anchor-seal when the time comes. Now if I seal the log end`s, should i reseal the timber after milling?
Quote from: shiver_me_timbers on March 21, 2014, 12:56:30 PM
I will definitely seal them with anchor-seal when the time comes. Now if I seal the log end`s, should i reseal the timber after milling?
Only if the end has been re-cut or a fresh cut is made. Unless the anchorseal has been rubbed off.
Jim Rogers
All the timber framers I sell wood to want green, Fresh wood, they say the frame tighten up when it drys. :)
I don't think shrinkage is the desirable feature. It's the fact that green wood is much easier to cut with a chisel and other tools when cutting the joints. The moisture acts as a lubricant and make the wood softer. You will have far less tendency to chip out like you could when working with dry wood.
I will be cutting my frame this summer, as that is when I have the free time. I will either get the frame erect and sheathed/roofed, or store the frame over winter for spring erection. Which path I take depends on timing and funds. I don't really want to put the frame up and leave it exposed all winter.
Any thoughts on timing in this case?
I'd let it dry as much as it can over winter and frame after. Winter is a time of accelerated drying. No matter if green or dry wood, you will be cutting every joint just as precisely. Given the choice, we would all want them to stay just like we made them. Yes dry wood is tougher to work, but by the same token you might gain time in the fitting phase by eliminating movement and shrinkage that occurs between framing and raising.
Anchor seal is your friend.
You really need it for woods like Ash.
Coat it as soon as you buck it.
The seal works great on getting tenons to slide in too.
Anybody else use that for tenons too?
I've been using Anchorseal2 on every joint that I cut. It only takes a few minutes and it really seems to make a difference in the amount of checking and splitting that occurs (white pine). My understanding is that anchorseal2 doesn't leave as thick a waxy layer on the surface as the original formulation (both are available) but there is still plenty to help the joint slide together (but as a disclaimer - I have not actually assembled a frame yet - still in the process, my experience is only test fitting of joints). One other note - when first applied on white pine there is a distinct yellow colour - but it seems to fade away with time.