A tree is a tree – what’s the difference?
In short, the species of tree you choose for your log home can make a huge difference. Northern White Cedar (Thuja occidentalis) provides many advantages over pine, a commonly used wood in log homes.
Rot Resistance & Insects
- Northern White Cedar naturally produces preservatives that make it one of the most decay and rot resistant of woods, as well as insect tolerant. In a 1995 study, cedar flake board panels in Hawaii showed no symptoms of termite attack, despite two years of extensive termite exposure.1 Cedar displays minimal cracking or checking because of its lower moisture content, and any checks will not penetrate through the heartwood of the log.
- Pine is not naturally resistant to rot or insects. Pine requires kiln drying to kill insects in the wood, and preservative treatments to prevent future rot and insect damage. Surface treatments for pine lose their protective abilities once logs begin to crack and open up untreated areas. Large cracks in pine are common because of the higher moisture content.
Water Content
- Northern White Cedar has less water content when green weighing about 3500 lbs. per cord.(2) Katahdin naturally air dries to a desirable 14-16 percent moisture level in a fairly short time, as little as three months. Air-drying allows the wood to acclimate to a new moisture level without harming the wood fiber’s molecular structure. Depending on the weather, a brief finishing may be necessary. Katahdin’s “green” kiln is heated using their biomass boiler to create steam heat.
- Green pine weighs an average of 4700 lbs per cord, with more than twice the water content that cedar does.(2) Pine characteristically retains its water and usually is dried in a kiln to season the wood. Because the water is forced out quickly, cell rupture becomes a possible risk, which can weaken fibers and lead to cracking.
Durability
- Untreated Northern White Cedar possesses high natural durability. A study conducted by University of Maine found that surveyors’ cedar corner posts and rail fences were still serviceable after 50 to 60 years of use.(2)
- Untreated pine has a life expectancy of 3 to 7 years when in contact with the ground.(3)
Thermal rating (R-value)
The R-value is used to measure how well a material resists the flow of heat through it.
- Northern White Cedar has an R-value of 1.41 per inch of thickness, the highest R-value of any of the species used in log homes.(4)
- Pine species used in log home construction have an average R-value of 1.25 per inch of thickness.(4)
Thermal Mass Factor
Another measure is Thermal Mass, which reflects a material’s density (in pounds per cubic foot) and its specific mass. The higher the R-Value/Thermal Mass Factor, the easier your home is to heat.
- Northern White Cedarhas an R-Value/Thermal Mass Factor of 3.78.(5)
- Pine has an R-Value/Thermal Mass Factor of 2.76.(5)
Sustainability
- Northern White Cedaris a renewable resource that is actively managed to ensure biodiversity, wildlife habitat and high-quality forest products.
- Pine plantations are able to produce usable timber in relatively short periods of time, but they require a tremendous amount of resources to stump, seed, and prepare seedlings. Unlike cedar, which has natural resistance to insects and other pests, pine plantations need to use phosphate fertilizers, herbicides and insecticides to maintain healthy growth.
Sources:
- Haataja, B.A. and P.E. Laks. 1995. Properties of flakeboard made from northern white-cedar. Forest Products Journal 45(1): 68-70
- University of Maine-Orono – Forest Products Laboratory and Forest Service, U.S. Dept. of Agriculture
- Forest Service, U.S. Dept. of Agriculture
- U.S. Dept. of Agriculture – Wood Handbook
- ASHRAE Handbook, American Society of Heating, Refrigeration and Air-conditioning Engineers