Wood technologists tell us that the fiber saturation level of wood is reached when it holds a moisture content of about 28%. They also point out that wood shrinks approximately 1% for every 4 percentage points below the 28% level. To insure maximum satisfaction, the lumber should be dried or “pre-shrunk” before installation. Changing conditions such as rain, temperature, sun, shade, and relative humidity will all affect the moisture content of wood. Thus, some changes in its size can be expected. Experience has shown that lumber dried to 19% moisture content, installed outdoors, will undergo limited dimensional changes. Warpage, another result of lumber shrinkage, is also minimized when the wood has been properly dried prior to installation. All lumber shrinks as it dries. The place for this shrinkage to occur is under controlled circumstances at the treating plant, not after it is erected in a home or other structure.