The pickets of the fence in the picture above are going to be Western Red Cedar Pickets
Western Red Cedar
This species of lumber is best for any type of board or picket fence – as long as the bottom of the fence is not continually touching the ground. Cedar is a very stable wood. It does not warp, shrink, or check, (split), as pressure treated pine will likely do eventually. Pressure treated (PT) pine boards can warp and shrink as quickly as one month after installation. At 10 years, a fence using cedar boards will have a much nicer appearance, compared to a pressure treated pine board fence.
The pickets of the fence in the picture above are going to be Pressure-Treated Pine Pickets
This pine, after it has been cut to size, is first kiln dried to remove most of the moisture. Then it is bundled up and put into huge cylindrical tanks. Next, a water based solution of micronized copper azole is forced into the wood fibers using pressure. This process makes the wood very heavy and gives it a dark green appearance.
Pressure-Treated Pine is supposed to go up to 20 years without decay or insect damage. It is not guaranteed against shrinkage, warping, or checking (splitting). We do not guarantee that this will not happen, because it often does. When PT pine starts drying out, it can develop “checks” which look like splits or cracks in the posts or boards. This is a common complaint from new owners of wood fencing. Actually, the wood is shrinking slightly, a natural seasoning (drying out) of any piece of lumber.