Quote Originally Posted by Frank Broughton View Post
Two not trues, you are just assuming there are many homes with 3 4 or 5 layers. I call that one out, no way on 4 or 5... it is impossible almost. Second, roofs are not striped to the joists. With the old shake shingles there were nailing strips of 3/4 lumber nailed to the joists. You strip to that, then add 1/2 osb or plywood. No one strips to the joists. That would be a nightmare as no way the old houses are 16 on center.
When I said 4 or 5 layers...it was worse case with houses 100 years old and counting old shake singles which the COB considers one roof, then many times roll roofing is found , and other layers, sometime 1 or 2 layers of 240lb asphalt shingles...many of the new suburbs, this is not the case but I speak from experience as an owner of homes nearly 100 years old, in the city.
and yes, there are slats across the rafters, but if they are rotted as in worse case scenarios, I have seen them pulled of which is an expensive nightmare, especially where rafters are not 16" o.c., but 23 /24" o.c. and 3/4 plywood cdx, not 1/2 partcle sheathing as is usually used.