This invention relates to modular construction panels for use in building residential homes and farm buildings. In particular, the invention relates to a solid wall construction panel made from indigenous natural resources.
Many designs exist for the construction of log-type buildings. Standard log construction demands a large supply of long (20 feet or more) uniform from top to butt logs with few knots. In a typical situation, pine logs having long lengths, little taper and few knots are often turned on a turning mill machine, then grooved and channeled for chinkless installation as the outer wall of a log home or cabin. Trees indigenous to the upper Midwest, such as Balsam, Spruce, Aspen, Cottonwoods and Fir fail to have long lengths, non-tapering trunks and often have many knots. Their uses hereto now has been relegated to the pulpwood industry for making paper, chipboard or fuel pellets with only a limited application as lumber.
U.S. Pat. No. 1,445,738 to Adams discloses a portable bungalow built of vertically disposed logs which must be generally non-tapering in order to align side-by-side. A log cabin patent, U.S. Pat. No. 1,980,660 to Bonn, discloses an outside wall made of staggered, semi-circular logs designed to butt together and, therefore, must be generally non-tapering from top to bottom. Yet another design, U.S. Pat. No. 1,902,309 to Muffley et al discloses a wall structure for a log cabin wherein each log must mate in substantially flat contact with an opposing log, thereby requiring that the logs do not taper along their length.
Timber tree species native to the upper Midwest and found throughout many areas of the United States have very high insulating or "R" factors. At 12% moisture content, the following table gives some representative species and the corresponding "R" factor.
______________________________________ Species "R" Factor Per Inch ______________________________________ White Cedar 1.41 Balsam Popul 1.33 Black Spruce 1.16 Aspen 1.22 Cottonwood 1.23 Jack Pine 1.20 Balsam Fir 1.27 ______________________________________
The "R" factors in the table are high in contrast to White Oak which has an "R" factor of 0.79 per inch. All of the listed species are moderately easy to work with and generally low in shrinkage, which are desirable qualities in log construction.