Logs boast a natural characteristic called “thermal mass”. This means that logs have the ability to absorb heat, keeping the house cool in the summer and conversely, storing that same heat in the winter and gradually releasing it at night, warming the house. This wonderful effect reduces overall energy needs and costs by as much as 30% over a conventional home, according to studies by the National Bureau of Standards.
It is important to understand that the “R” value (A measure of resistance to the flow of heat) is not the only method to quantify insulating qualities. The fiberglass insulation industry and the Federal Government established “R” ratings in an attempt to set standards for energy efficiency. The “R” value of fiberglass insulation is determined by passing heat through the material when dry. There is no consideration given to radiation, solar input, storage capabilities or moisture. A log is a solid mass that absorbs and stores energy in its cellular structure and is able to release the stored energy back into the home maintaining a stable comfort level. Studies have found that the majority of heat loss is due to air leakage around doors, windows and outlets, just as in conventionally framed homes. The log home industry has made major strides in improving joinery and sealants which has substantially reduced air-infiltration rates.

Aside from energy efficiency, thermal mass also provides a quieter environment than a conventional frame home, thanks to the sound-deadening effects of wood, according to the Log Homes Council of the National Association of Home Builders. “The acoustical benefits of a log wall, therefore, are the reduced transmission provided by its solid mass and the sound deflection provided by the profile of the log (the angle, shape, and texture of the log surface).”
Species R-Value/Inch

Douglas Fir 0.94

Douglas Fir South 1.01

Hem-Fir 1.08

Mountain Hemlock 1.02

Alpine Fir 1.34

Engelmann Spruce 1.26

Lodgepole Pine 1.08

Ponderosa Pine 1.12

Idaho White Pine 1.19

Western Cedars 1.33

Western Hemlock 1.01