If I make it stronger

"Jerry J. Wass" wrote in message ...
Yep, the good old Forest Products Laboratory--book---Now, if Mr. Mitchell
could tell us where to find the B.S.V.36 (is the B British?) I would be
greatly appreciative.--Jerry

Try this link to what appears to be a renamed standard:
http://www.techstreet.com/cgi-bin/de...uct_id=1108781
But then again, maybe it's this one:
http://www.techstreet.com/cgi-bin/de...uct_id=1113167

Notice that the first document refers to spruce and fir. I suspect if
you use the usual standards for spruce on fir, regarding grain
orientation, etc. you'll be fine, without spending big bucks on a
British Standard that may not meet your objective.

So, to repeat links already shared, methinks these two will do you:

http://www.fpl.fs.fed.us/documnts/FP.../fplgtr113.htm FPL
manual

http://www.moneypit.net/~pratt/ac43/ac43chp1.zip AC 43.13, or the FAA
link:
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/99c827db9baac81b86256b4500596c4e/$FILE/Chapter%2001.pdf

Rather than Douglas Fir, if you live in the Western part of North
America, consider "Western White Wood", which is a catch-all for
various hemlocks, firs, and larches. The strength properties are
acceptable, and the grain is far easier to deal with than Douglas Fir.
Available at Home Depots everywhere, just select with extreme care,
and start by looking in the shelving and trim wood section.