Jesse R Strawbridge :
If I have my facts straight, fir would be lighter than pine and more
resistant to rot/water damage.

That's true, and should be available for not too outrageous prices (this
is a lumber wasteland). Now that you mention it ISTR that birch is
rather rot prone as well. Leaves the choices of luan plywood and fir. If
I could get ash for a decent price...

/Par

--
Par
Men never do evil so completely and cheerfully as when they do it from
religious conviction.
-- Blaise Pascal (1623-1662)