I agree with Grumpy's advice to correct the ventilation problems and address any mold problems, but...
And while it is probably best to remove the old sheathing before installing the new...
That does not really address the question of adding new plywood over old.
As long as your building code permits its and it does not add too much weight to the existing roof rafter system, there is no reason I can think of that would prevent the addition of a new roof deck over the old.
As long as the new plywood itself can span the distance and carry the roof, wind, seismic and snow loads for your region, adding new ply over old is just fine.
The new plywood thickness should be at least equal to the exusting plywood thickness.
|
Member Since
01/29/2003
Total Contributions
2225 Posts
|
Moderated by Handyman 
