Species & Sizes of Pressure Treated Wood

Treated wood is generally available as dimensional stock in 2x4’s, 2x6’s, 4x4’x, and 2x2’s for rail components. 5/4x6’s and 2x6’s for decking. 2x8’s, 2x10’s, 2x12’s for joists, stair stringers, and beams. 6x6’s for support posts. Also plywood.

The predominant species of treated wood is a regionally available softwood.  Most common are:

Southern Yellow Pine - Southern Pine is the most common deck framing material in eastern United States. It is strong and stiff. SYP logs yield a high proportion of sapwood which works well to absorb preservative.

Red and Ponderosa Pine – Less strong than SYP, found in Northern U.S. and Canada. 

Douglas fir – It is very strong and is less prone to warping and spitting than SYP. Predominant material found in western United States and Canada

Hem-fir – It is weaker and more prone to warping and splitting than Douglas fir, but more receptive to preservation. It encompasses a group of western species.

Wood Materials