Everyone needs to understand that the construction grade Douglas fir that is sold at stores like Lowe's, Home Depot, and the local Mom and Pop lumberyards must meet or exceed certain industry standards to be called construction grade lumber.
As the lumber mill, cuts the trees into usable lumber, they will inspect and make sure that their lumber meets this standard and reject lumber that do not meet it. What that means to Airplane builders is that occasionally we can find lumber at the store, that not only exceeds the standards of building lumber for our home....but that it will meet the standards required for aircraft wood too. It takes a careful eye and some knowledge of grading lumber to discover these hidden treasures. I will warn some you that lumber marked HEM/FIR and often sold as Douglas fir is in fact a mixture of hemlock wood and species of fir (not necessary Douglas fir). Then there is also the issue of moisture content to contend with. Brant Hollensbe DSM Iowa Bhollensbe at mchsi.com
