|Posted on Monday, May 26, 2003 - 11:35 pm: ||
I know that the recommended roof deck is rough sawn 1" boards, and I have found a local supply. The problem is the building department, a hurricane prone part of Florida. They insist that plywood is necessary to provide lateral bracing and a diaphram to transfer wind loads from the gable to the walls.
My question is this, would 3/4" BC Exterior Rated plywood be Ok under slate, or should I try and fight the inspectors for approval? It seems to me that most plywood used on roofs is CDX, which is only rated exposure 1 (not for permanent exposure to the elements). Could I prevent future delaminating by using a thicker, true Exterior rated plywood?
|Posted on Thursday, May 29, 2003 - 10:14 pm: ||
Yes, you can slate over the plywood and it may last quite a long time if the plywood is a true exterior rated material. However, it will probably not out last a natural board and it will probably be a lot more expensive, which is why I recommend board decking (and for other reasons as well). However, it would be better to install a slate roof on an exterior 3/4" plywood deck than to not install slate at all.
|Posted on Monday, October 06, 2003 - 11:47 pm: ||
Well I am in to deep. I am building a new house in New York City and I have already installed 5/8” CDX plywood as per my engineer. I want to install 12” long ¼” thick random width Vermont slate. The engineer told me that the weight will not be a problem. But after reading this massage board I now realize that I have a problem. I hear that it is impossible to nail the slate proplery into the 5/8” CDX, can I screw it in? Is there any way around this. Can I nail lath board on top of the plywood if so what size board? Help!!!
|Posted on Tuesday, October 07, 2003 - 12:26 am: ||
I would nail 1"x4" lath board on top of the felted plywood. If you are actually installing 12" long slate (which is *extremely* short), with a 3" headlap, then you would have to install the lath boards every 4.5" on center. Double the lath at the bottom of the roof and at the top (or install a wider board at the bottom and the top).