If Fred plans to build a plane from wood purchased from Home Depot, he
should also build a pine box. He will need it. I have never found
wood acceptable for aircraft at HD or any other such outlet. Why pass
on such bad information?

Must disagree with this. You should look a little harder. I have many
board feet of really tight grained, vertical sawn, dry, straight
hemlock (not hemfir, a fast growing commercial mutant wood) found right
in the trim/banister section of our local Sutherlands. Our
independant lumber outlet occasionally has 8/4 shop doug fir that also
meets AC standards for all criteria. I know of a couple of Piets built
long ago with white pine ribs with hardware store flashing leading
edges.

Years ago, I heard one of the FAA guys give a lecture about final
inspections and the use of AC grade materials. At that time he made a
comment that homebuilders were the ones that certified the materials
and that as far as they were concerned you could use wet cardboard and
shaving cream to build your plane. As long as you could back up your
material choice with a least some data anything went. However, he did
mention that they could also restrict you to 200+ hours ground (taxi)
testing prior to flight.

Even Rutan ignored the AC quality thing on the first Vari-eze since
there wasn't ( and may still not be) anything such as AC certified foam.