On 2008-04-06, DerbyDad03 wrote:

I have 3/4" tongue & groove under the shingles, not plywood. He didn't
look in the attic.

If you are in a high wind or seismic area, you may wish to consider
going over all the T&G 1x with 1/2" plywood to improve the shear
resistance of the roof. Of course, the wall sheathing would be more
important to strengthen, but it is presumably not accessible.

Cheers, Wayne