Timber Frame Questions and Answers
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Q: How does timber framing fit in a green building environment?

A: Use local materials. That to me, is one of the major components of a sensible building system. In New England, where I live, our forests are mature again and we have plenty of good timber that can be sustainably and selectively harvested and processed at local sawmillls. Portable sawmills are also very popular that can go right into the woods. All of this avoids the transportation costs, embodied energy and fuel associated with materials shipped from far away, and it supports the local economy. Even with certified timber I would hesitate to buy it if it came from across the country. So for you folks out in the desert or plains without trees, I suggest you look to one of the earth based building systems using local materials, at least for the walls, if you're trying to be truly green.     

Timber frames also are valued more highly, are usually inside the building envelope, and are thus cared for better than a light-framed house. So they will generally last for centuries, as opposed to less than 100 years for a typical modern house. Thus, for about the same amount of framing wood, you get a house that will last 2-3 times longer.

Q: How are timber frames enclosed?

A: The majority of contractor-built timber framed homes use Structural Insulated Panels (SIPs) that get nailed onto the outside of the frame. (SIPs can be the subject of a lot of debate - they have some advantages from a green standpoint - but we'll save that for later.) These go on very fast, thus saving labor (=money), and make a very energy-efficient envelope. But if you're doing your own labor, there are other alternatives such as light framing and Larsen trusses nailed outside the frame that allow you to use conventional insulation or sprayed-in systems, or you can use strawbale or slip-formed earth systems. One thing that is common to all of these systems is that they are outside the timber frame, thus keeping the frame exposed to the warm interior where it is protected. This is important in a cold climate; burying the frame in the wall could cause condensation and rot if the sealing details are not done well. This is not as big an issue in a dry or warm climate, but you still have the problem of finishing your infilled wall up against the sides of the timbers that you avoid by putting your wall outside the frame.

Q: I'm looking for a primer on building with roundwood. That is, I would like to learn how to do framing with non-milled poles. You will occasionally see beautiful natural buildings (cob, strawbale, slipstraw, etc.) that are supported in this way. I have yet to find a guide that addresses joinery and design.

A: Log Construction Manual by Rob Chambers, available from the International Log Builders Association. And the three part series of articles on scribing that appeared in the quarterly journal Timber Framing   from the Timber Framers Guild.

Q: What is the best way to get the bark off of timber and why is it advisable to do this?

A: (Kelly) It is easiest to debark trees when they are still wet with sap, since the bark will often peel off by just pulling on it; once they are dry, it is often necessary to use a draw knife, or some similar tool to debark them. Leaving the bark on can provide a place for insects to reside, either living there before or after  installation. Also the bark is much more likely to shed debris over time.

Q: Why do you ignore log home structures as a natural alternative? Built with standing dead wood the structure is masssively energy effecient, is a huge carbon sink, and left to to decay in the forest re-emits the carbon it absorbed when living. I would love to know why a sip panel is promoted and a log wall is not. A sip carries a huge carbon footprint during the manufacturing process. The efeciency of both walls are the same but the log wall is purely a natural fiber and a sip is a massive synthetic. Don't understand your rational.

A: (Kelly) I like log homes, and in some circustances it makes a lot of sense to build them. This is generally true when there is a local source of surplus logs that need to be thinned sustainably from the forest. Otherwise, to harvest logs just for a log home when it is necessary to either cut down productive forests or to ship the logs much distance it doesn't make sustainable sense. It takes a lot of logs to build a log home. Another issue with log homes is that they do not naturally provide very much insulation, compared to many other materials.

I feel that too often log homes are promoted as natural alternatives without attention to these factors, so in the interest of saving our forests (which sequester much CO2 and provide needed habitat), I have not devoted much attention to them. I do adovocate the use of logs for timber framing under similar circumstances. I don't really promote SIP's; I only recognize that they have a place in the realm of sustainable building, just as log homes do.