I’m always searching for new ways to utilize small diameter poles, which are abundant throughout western US forests and elsewhere. Because of poor forestry management, U.S. forests are now choked with small diameter trees. Thinning these trees has become a Forest Service priority to reduce the risk of forest fires that destroy around 5 – 10 million acres of timber every year and endanger many communities. What a waste! With an inexpensive firewood permit (about $25) anyone can obtain this wood for building. Even though this wood could be used for firewood, it’s more valuable as a building material. This article describes an alternative roof design for those building in areas without building codes.
This double pole roof design is very simple. Roof poles are raised on a frame wall to create sufficient space for a superinsulated roof. From below, the sloped ceiling features exposed wood poles, and tongue and groove wood. The drawing is pretty much self explanatory, but a few points are worth noting.
A center pole design such as this is suitable for round, octagonal, hexagonal and similar shaped structures. Instead of a center pole, you could build a column using CEBs, adobes, stone or other suitable material. I have one house plan (see Native Spirit design) that uses a high mass column like this with a wood stove pipe going up the center. For rectilinear designs, a similar double pole roof could be built with a bearing wall or beam down the center.
Choose poles that are straight as possible. You may want to use a power planer, circular powersaw or chainsaw to straighten out the top surface. Otherwise, the T&G ceiling and roofing will be wavy and more difficult to build.
Wood in the round is about 20% stronger than standard dimension lumber. Just be sure to look carefully at each pole for defects: cracks (especially those perpendicular to the grain), insect damage and any soft areas. Remove the bark and always keep the bow up for maximum strength.
If you decide to build this way, draw a roof plan. It will help you visualize details such as framing members between poles. Most likely some extra framing will be needed. More poles could be used for this or you may opt for dimension lumber to help create a flat surface. Either way, poles and dimension lumber can be coped on the ends to fit against the main roof poles.
Use the roof plan to check how poles will fit together. For instance, you may have to build a larger column or fabricate a steel bracket to get all the poles to fit at the peak.
A key benefit of this design is using wood that is sustainably harvested in a manner that improves the health of the forest and reduces forest fires. Using locally available wood reduces construction costs and avoids supporting environmentally irresponsible logging companies.
Timber-frame or pole construction is also more aesthetically pleasing than conventional wood-frame construction covered with sheetrock. A little extra effort working with poles will reward you with a stunningly beautiful wood ceiling and superinsulated roof at very reasonable cost.