Basics of Log Home Building and Timber Frame

Our third type of alternative housing construction... minor editing... from http://www.smart-homeowner.com/ME2/Audiences/dirmod.asp?sid=&nm=&type=Publishing&mod=Publications%3A%3AArticle&mid=8F3A7027421841978F18BE895F87F791&tier=4&id=65CBA1EE3F6142C2ABB71B19F8A0D430&AudID=Better%20Home%2C%20Better%20Planet

Log Homes
Thermal mass is a term you hear a lot when considering a prefabricated log home. It has been a touchy point when log home advocates debate proponents of other types of home construction. To understand it, a working knowledge of how log homes are built is essential. Log homes today are far more than rough logs stacked one on another, as was the case in Abraham Lincoln's day. Still, log home walls are essentially solid wood. The same timber that faces the outdoors also has a side that faces indoors. But that's where the similarities end. The 'logs' of today are more akin to carefully cut timbers, fitted together for maximum airtight integrity. Indeed, the only thing that looks like a debarked log is the exterior-facing, finished surface. The ends of these 'logs' are notched in the traditional manner, interlocking at the corners of the structure. But along the mating surfaces, most logs in kits fit together like stacked tongue-and-groove lumber, usually with a weatherproof sealant at the mating surfaces for good measure. When finished, the only insulation between you and the elements is that wall of logs. Some have argued that an 8-inch wall of wood does not have as high an R-value as a standard 8-inch wall filled with insulation. That's true. But log home advocates quickly point out that the thermal mass of the logs prevents heat loss in the manner in which heat is rapidly lost through an ordinary wall. Many experts agree and have concluded that heating or cooling a log home is about on par with most other modern building methods. Beyond that, log homes lend themselves strongly to an open approach to interior design. Although newly cut softwood logs are a creamy whitish or light brown color when first installed, they do darken considerably over time, becoming various shades of medium to dark brown, depending on the species of wood used. With a fairly open interior and a generous amount of natural lighting, the gloominess these colors impart is easily dispelled. For the environmentally conscious log-home builder, the National Association of Home Builders says log homes are no threat to the nation's forests. The association says that 37 percent more timber is grown than harvested each year and that all new-home construction accounts for barely 50 percent of that harvested timber anyway. (The rest goes to pulp and paper manufacture.) Moreover, log homes account for only 3 to 5 percent of all new homes built, the association says. So it appears a log home has little impact on ecological concerns in the nation's forests.

Timber Frame
The big sticking point with the post-and-beam revival in the 1970s and 80s was the demand for extra materials and high labor costs. In essence, those early timber-framed homes were built twice: once for the labor-intensive, post-and-beam skeleton and then again using variations on standard stud framing for the surrounding shell of energy-efficient walls, roof, windows and doors. Now, both the labor and materials problems have been largely solved. Precutting all timbers at a central mill has reduced labor. This controlled environment offers much-improved results over earlier on-site efforts. When milled offsite, the timbers can be monitored for structural viability and moisture content, both crucial factors in the long-term stability and appearance of the house. They can also be cut more precisely, so the integrity of the joints is never left up to how somebody feels on a given workday. Both materials and labor have been saved with the advent of special structural panels for the exterior walls and roof of a timber-framed home. These ingenious panels are like a big ice cream sandwich with the exterior wall on one side, the interior wall on the other and, in between, a hefty layer of solid foam insulation. The R-value for such a panel (often called a stressed-skin panel) is well above the R-20 generally recommended for walls. The panels are locked together by using one of several clever building devices and, if done correctly, an airtight structure is assured. Little tunnels for plumbing and electrical necessities are cut in the foam before the panels go together. It's all a remarkable step forward from 'the good old days' of timber framing. The interior surfaces of these wall panels are basically the same as surfaces in homes built by more conventional means. Thus, in interior finish work, you can design anything from the rustic, open approach to a more refined 'paint-and-paper' interior. Of course, kit construction does put some limitations on the design of your timber-framed home, which will cost 10 to 20 percent more than a comparable stick-built home. Some manufacturers will precut a custom-designed home, but that drives up the costs again.

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