Leaning Trees used in Timber Frame

[jacobcbass]

Hey FF,

I am in the planning process for a 36'x34' Timber Frame Carport to be logged, milled, chiseled, and raised on our farm. Jim Rogers has done the custom design, and is now finishing up the Cut Sheet Drawings. It will be all SYP that's standing right beside where the building will be raised. I will be falling trees this winter. Most of the frame will be 10"x10" and 8"x10" timbers with lengths from 7'-21' long.

My question here is: Can I use the affects of leaning trees to my advantage. I have 6-10 tall beautifully straight grained, large trees with very few knots, but they are leaning. I have other tree as well but these are really nice other than the lean. If I mark the tension/compression side of these trees, can I plan for stress tendencies as the timbers dry in my frame.

What would you use the leaning trees for? These trees are way to big and straight to not get used. I just don't have the knowledge to know what to expect from them. Where best should they be used and in what orientation? What can I expect from these trees? I'll get some pictures of the trees but not sure how well the lean will be portrayed.



I have been following along here for awhile now. I found Jim's Timber Frame class here last year, took the class, learned a ton. Then bought a sawmill, bought a tractor with loader and logging winch, and bought tons of tools! I've been reading and watching everything I can find on Timber Framing for a solid year now. I'm very excited to start this project!

Thanks for the help! Jake

[Don P]

Pine responds to a lean by producing compression wood on the underside of the lean. It is stiffer, it has a higher "E" value but is weaker in bending, a lower "Fb". That describes a post if it is not an abnormal amount of compression wood. Also pay attention to slope of grain. The downside of compression wood is similar to juvenile wood, the fibrils that form the cell wall run at a bias to the length of the cell. As the wood dries it shrinks lengthwise to some degree depending on the severity of the compression wood. If it is on one side of a timber, as in a leaning tree with compression wood on one side of the lean, it will likely bow or crook while drying. The safest bet is to pay attention to severity while sawing and dry it as much as possible prior to deciding if it is useable.

This is a pic I had in my gallery showing what is going on there;



 

[Chilterns]

Hi Jake,

You are possibly making the mistake of trying to match the timbers that you have cut to a design that has been produced independant of the trees felled.

Where you have a load of bent timbers then it might be better to consider how these could best be employed in your timber frame design. Trees that have been leaning will probably contain quite a bit of reaction wood that will cause deformation in timber following conversion and so if you can convert and use your timber in boxed heart form then the effect of releasing internal stresses can probably be kept to a minimum.

Leaving timbers to dry and relax for a while can also help reduce timber movement in the timber-frame. 

[Jim_Rogers]

As you are new to sawmilling, you'll need to learn to "read" the log. That is to watch what is happening as you mill it.
Removing one board/plank from one side of the log will release some stress/tension.
And that may cause it to move/bow. 
You'll have to then cut the opposite side of the log to try and release some tension on that side to offset the movement.
As mentioned, you'll have to view the timber and decide where it can be best used in the timber frame.
I'm not sure if I could give you any advice about using a leaning tree upfront.

Jim Rogers

[Prizl tha Chizl]

Hi Jake,
I'm relatively new here also, and my first reaction to your post was, "great question!" My mind went to the rafters and load bearing beams, after all, they would want to sag somewhat once loaded, so why not orient these guys with their reaction wood so that it will want to counteract that tendency. They always tell us to crown our rafters, right?
However, after reading the other guys' posts, and with my own limited experience struggling to fit joints in beams that had moved after they were cut, I think I'd try to stay away from using them in any of the larger timbers.

 Is there any smaller dimensional sawn lumber in your building, ie roof decking? It seems like if you sawed them into boards perpendicular to the reaction wood they should not develop too much crown. Otherwise I'd want them for braces, as they'll move less over their short length, or rafters, but this time saw them so they will tend to crown, as it's hell trying to straighten 3x or 4x once it's up in the air. If your rafters and braces are the same dimension you could saw them all to accommodate either, and then use your cull rafters for brace stock.

Please keep posting as you go, it's nice to see what other people are doing, and how it works out.

Good luck, and have fun with your project!