Log Homes - Choosing a Wood Type

Softwoods such as the pines, cedars, and spruces, are generally chosen for log home construction because of their superior thermal characteristics, ease of handling, attractive appearance, relatively low cost, and ready availability. But other types are used as well. Therefore, we'll present you with the information and you can make up your own mind.

Each wood species has both advantages and drawbacks. No single species can be considered absolutely "best" for log home construction. Some of the characteristics to consider are: appearance (color, grain, knots), stability (resistance to warping, shrinking, and checking), resistance to decay and insects, thermal qualities (how well it insulates and reduces heat transfer), workability, ability to accept protectant stains, and of course, cost.

Here are some of the most common wood species used in log home construction:

White Pine - Very popular species for log home construction in the Eastern part of the U.S. Light color (white to pale yellow/brown), lightweight, soft, easy to work with, straight uniform grain, moderately resistant to decay, relatively inexpensive, strong, very stable when dry (low shrinkage and warping) , takes preservative stains well, ages to a deep orange color. Because of its low density, it has excellent thermal characteristics. In summary, White Pine is an excellent choice for log homes because it is readily available, not expensive, stable, easily worked, and is attractive.

Red Cedar - Along with White Pine, Western Red Cedar is one of the most popular wood species for log homes. Beautiful color, aromatic, red heartwood, white sapwood, soft (low density, lightweight), low strength, low shrinkage, straight grain, easy to work, resistant to weather decay and insects (good for wet climates), low initial moisture content, non-resinous, and excellent thermal performance. It is relatively easy to stain and moderately expensive. In summary, Red Cedar is a good choice for log homes, although somewhat expensive, because it is naturally resistant to water and insects, looks good, smells good, and is easy to work with.

White Cedar - Northern White Cedar is similar in characteristics to its Western Red Cedar cousin. Because it also has a low initial moisture content, it can be easily air dried. It is also very resistant to decay and insects.

Yellow Pine - Harder than White Pine, relatively easy to work, pale yellow with brown knots, dark and light grain pattern, not as good as White Pine for accepting stains. It has a high resin content, is more decay resistant than other Pines, but not as good as Cedar, is relatively inexpensive, is less dimensionally stable than other woods. Great for floors, framing, and furniture, but White Pine is better for log home walls.

Red Pine - Sometimes called Norway Pine. Almost identical to White Pine in characteristics although a little heavier, stronger, and more resinous. Found primairly in the Great Lakes region and New England. Color is pale red to reddish brown.

Oak - Not used often in log homes, various colors from pale white-brown to reddish, beautiful grain, heavyweight, very strong, stable, difficult to work. It is very resistant to water and decay, expensive, and accepts stains very well. A good choice for log homes if you can find it and can afford it.

Douglas Fir - Very strong, stiff, soft, straight grain, medium weight, easy to work, beautifully uniform light reddish brown color, relatively decay resistant, and accepts stain moderately well. May be susceptible to warping and checking in dry climates. Excellent thermal performance. Inexpensive. Commonly used for long beams and trusses where strength is of concern.

Spruce - Principally in the Northern parts of the U.S. and Canada, light in color, straight grained, small knots, soft, lightweight and resinous. Spruce dries easily and is very stable. It is moderately strong, stiff and tough, is soft and easily worked and stained. Only slightly decay resistant and good in dry climates. Relatively inexpensive.

Lodgepole Pine - Found in Western North America from California through British Columbia into the Western Yukon, beautiful wood, soft, is stable and resistant to checking in dry climates, easy to stain. A popular choice for handcrafted log homes in Western U.S. and Canada.

Hemlock - Western hemlock is found in Western states although used by log home companies in other areas, is off-white in color with small knots, soft and lightweight but strong, straight grain, easy to work, stain, and is stable. It works well for log homes because it can be produced in long lengths. Relatively inexpensive, not accounting for any long-distance shipping costs.

Cypress - Found in the Southern U.S., cypress is a dense wood that is very decay and insect resistant and durable, but difficult to work with. Light brown in color, it is dimensionally stable when dried, but very difficult to dry properly. Smells like Cedar, no resins, takes stains well. Moderately expensive.

Definition of Characteristics

Cost - The cost of logs of a particular wood species depends on availability, market prices, and shipping costs. In general, you'll achieve the lowest costs by selecting wood types that are readily available in the area in which the log home company facilities are located, which is usually the wood type recommended by the company.

Appearance - Beauty is in the eye of the beholder, as the old adage goes. Wood characteristics that contribute to appearance are color (sapwood and heartwood), uniformity or variation in color contrast, grain pattern, grain straightness, knots (or absence of), density, and end grain (affects corner appearance).

Softness/Hardness - Soft woods are generally lightweight and easier to work with but can scratch and dent easily. Care must be taken at the factory, during shipping, and during construction to prevent damage. Most woods used for log home construction are in the softwoods category.

Workability - Woods that are easy to work make the manufacturing process easier, less expensive, and produces more consistent results. Construction work at the job site goes better when cutting, trimming, drilling, and fastening are easier. Labor costs are lower for woods that are easy to work with.

Strength - A wood's ability to resist bending under load is important when long lengths are used in wide load-bearing walls and for beams or trusses.

Thermal Performance - Although all logs have good thermal properties, some are better than others. Thermal performance is a combined measure of both the heat conductivity ("R" value) and thermal diffusivity, sometimes called thermal mass effect. Less dense woods, such as cedars and pines, have higher "R" values (make better insulators), but lower thermal mass (heat storage and transfer delay). High density woods, such as the oaks, and hickories, make poorer insulators (lower "R" value) but are better in heat storage/delay. The best woods are those that have the best combination of the two measures: moderately dense woods such as some pines, Western Larch, and Douglas Fir. Large diameter logs have better thermal performance than small diameters. For additonal information on this topic, see this page.

Decay and Insect Resistance - Some woods, such as the cedars, have built-in preservatives that help prevent decay and insects in unprotected logs. However, all woods should be protected with artificial preservatives and stains, even the cedars, because natural preservatives will degenerate over a period of time. Therefore, a wood's natural ability to resist decay and insects should not be an overriding factor when selecting a wood type.

Ability to Accept Protective Stains - Some woods accept protective treatment and colored stains better than others. Generally, those woods with high resin content tend to be the worst. Very soft woods, even though they accept stains well, tend to stain unevenly, which can create a blotchy appearance.

Stability - Highly stable woods are not susceptible to excessive shrinking, cracking, bending, warping, or twisting after they've been dried and used in home construction. Some woods work better in dry climates, others are better in more humid climates. A general rule of thumb is that a wood specie works best in the same kind of [humidity] environment in which it grew in the forest.

Summary

Generally, you should be careful when deciding on wood types based on general definitions of characteristics. Trees from different stands in the same forest can differ in characteristics. Individual logs of the same variety can have significantly different characteristics, often greater than the general differences between varieties.

For a very detailed and technical treatment of wood types and characteristics, see the U.S. Department of Agriculture - Wood Handbook.

+++