I am in the designing stage of building my own timber frame home and have a few design questions. A small bit of background on myself my help in getting my questions answered. I own 200 acres in the North Georgia area of old growth forest with large numbers of pine, popular, hickory, cherry, ash, and a few more. My plans of now are to supply the lumber yard with all timber that I will need to construction the house.

Here in the South the readily available and widely use type of wood for posts and beams is pine. My question is this: Is pine use because it is the best or because it is cheap? If not the best, What type of wood is and why?

And

I am wanting to span 24' across the middle of the house with no support columns with an steel "I" beam. What size "I" beam do I need to use or is this a bad idea (the "I" beam will be holding most of the weight of the second floor)?

Thanks for all the help.
Benjamin

A timberframe bent can easily clear span 24 feet(with a floor on the tie beam). Why would you want to use a steel I-beam? Over time, wood and steel don't particularly like each other. Timberframers typically like to stick to all wood. Also, I think the term lumber is typically reserved for dimensional and standard lumber sizes. Timberframes use larger, non-standard sticks called timbers.

Many woods can be and were used in timberframes. The sizing of the timbers depends on the properties of the wood species you want to use versus the loads they have to support. Shear load parallel to and against the grain are available for all the native species. Pine was used a lot probably becuase it was the most prevalent species and therefore I'm sure the cost was often times most effective. The size pine timber needed to support a given load may be equivalent to an oak timber of much smaller size. The size is also partially governed by the size mortise and tennons. They are not typically smaller than 1.5 inches in hardwood frames and there are general guidelines for the meat needed (often referred to as relish) on either side of the mortise. So that will determine the smallest size of a timber generally. Other than that, what wood species you use depends on what you want to use, and what is available to you. Some people prefer a certian grain pattern or look. You should definitely have all of the engineering calculations performed by a structural engineer lisenced in your state (preferebly with timberframe experience). All of the woods you menttioned can be used, but be careful of hickory. It can tend to check a lot when air drying and sometimes can check to the point of being unusable. Using it for braces might be ok if it is dried properly to minimize checking (seal the ends of the stock). Cherry is more often used for furniture becuase of the beauty of it's grain pattern, but I've recently seen someone make braces from it - beautiful. Black Walnut can also be a beautiful accent as a brace or spline. I have even seen it used for a post, but this is less often done becuase of the value of black walnut. It is usually reserved for furniture and the like because of it's higher value and beauty. It's one of the stronger native hardwoods though. I've recently been thinking about trying to use some Osage Orange for s spline or even a brace with some trees I've been eyeing. It's another very strong hardwood, but hard to get in any decent sufficiently clear size.
Recommended reading: A timberframe workshop by Steve Chappell

There is a ton of information listed in the archives of this forum. The "search tool" works really well. It might help you to check out this feature. It helped me.

You did not mention oak as a species in your woodlot. That wood be the obvious choice. Another tip is to talk to a sawyer and see what they like to cut. I know in my case the mill pretty much determined the maximum length of beams and the sawyer had some tips about what kinds of wood he liked to work with for certain applications.

Pine is a favoite of the mill for reasons of reliabilty and predictabilty. Good luck!