Timber Frame vs Post & Beam
What's the diffrence?
-Historic
-Structural
-Method
What is the Guilds position on this subject?
Any takers?
Can this be a new forum for debate?


[This message has been edited by wkooyman (edited 03-30-99).]

I'm not sure the Guild has a position on this so I'll just give you my personal answer.

The two methods have much in common (use of heavy timbers, methods of enclosure, and timber engineering) and differ only in the method of joinery. Timberframing joins the timbers using traditional mortise and tenons (as well as dovetails, housings and the like) and in its purest form uses nothing other than wood to secure the connections. Post and Beam relies on metal (bolts, nails, and metal plates) to secure the joints

As to history; clearly timberframing is the older method -- man had trees before he had steel. My personal theory is that post and beam evolved as a sort quick and dirty timber frame. Most joiners realized that they were spending a large percentage of their time cutting the joinery as opposed to sawing the timbers. Thus, a method that allowed quick interconnection of the pieces would speed up the process. Both methods declined in popularity as a mainstream method with the emergence of sawmills that could produce the dimensional lumber for stick framing. A stick frame is really just a post and beam with very little posts and beams.

Today there is a lot of overlap between the two methods. Many "timberframe" buildings have connections that are secured by concealed steel elements. The result being structures that can meet commercial building codes as well as achieve a higher level of engineering performance (larger free spans and simpler multi-member joints)

I agree with Brian's method of differentiation. I'm also inclined to believe that the incorporation of metal fasteners may parallel the developement of codes, engineering standards and plan reviews. Wooden joinery is very difficult to analize, due to the anisotropic properties of the basic components in the system (wood).

This problem still affects timber structures in ways that urk even the casual entusiast. For instance, timber frame bridges that have survived for over a century as true wooden trusses cannot be repaired without the addition of steel to "strengthen" the connections. Unfortunately this "improvement" invariably shortens the life of the truss, due to the incompatability of the materials, which is multiplied in an outdoor environment.

In a nutshell, timber framed vs post and beam is a classic example of you get what you pay for. Unfortunately, some customers don't realize they are paying for one, and getting the other.

I feel so enlightened. Prior to this reading I would have said "timber frame" and "post&beam" were just different terms for the same thing. I also learned a new word, "anisotropic" was it? I know an engineer who took down a 150 year old timber frame and re-erected it as a post&beam. One thing I did notice is that the steel joinery "sweats" in the summer and doesn't seem to be doing the timbers any favors.

I'd like to elaborate a little bit on the answers that have already been posted on this issue. The way I view it, post and beam is a structural system, while timber frame is a construction method. Any time distance is spanned by a horizontal member transferring its load to vertical members, it is post and beam. Timber frames are post and beam, as are modern timber homes with steel connectors. The Parthenon and other structures from classical Greece are post and beam. Modern steel skeleton skyscrapers are post and beam. Pole barns are post and beam. And stick-built houses are post and beam, as has been said, with the posts and beams reduced to minimal size. I would even maintain that geodesic domes are post and beam, although the demarcation between what is a post and what is a beam is somewhat blurred, since the whold structure forms a complex three-dimensional truss. Examples of construction that are not post and beam include log building, in which loads are transferred directly from one horizontal member to another until they reach the foundation; structural masonry, where horizontal lintels carry loads to solid walls on either side of the opening; and arches, both round as in the aquaducts of ancient Rome or the barrel vaults of the Washington DC subway system, and corbelled as in the temples of precolumbian mesoamarican civilizations. Anyone care to comment or elaborate?