I am considering proposals from two roofing companies to reroof my
home in the San Francisco Bay Area.  The roof has a normal slope and
is about 2700 square feet in size.  Both proposals call for the use of
40 year shingles on top of #30 felt.  Below the felt, Company "A"
proposes using a layer of 1/2" CDX Plywood; Company "B" proposes using
a layer of 7/16" OSB Ply Decking.  Briefly describe the cost,
compostion and qualities of each of these two materials.  Compare the
two for use in my home's new roof.  Mention any pertinent differences
including weight, strength, moisture tolerance and fire safety.  The
answer is required by 9/01/2004.  Thank you.

Switch to a metal roofing product.  Do an internet search for "metal roofing".
That will solve your problem.  May cost a bit more but metal roofing
is the premium product.