In a few weeks I hope to have installed a photovoltaic roof (electric solar power). The design is basically that of a concrete tile roof, because the solar cells are mounted in a tile (see at www.openenergycorp.com).
I live on Long Island, NY, USA. In this area just about everything is asphalt shingles, so expert advice is hard to find. The roof is to be installed by both a roofer and solar installer. This will be the first such install in this area.
Here is the design:
35 degree pitch (about 8 in 12 I think).
600 sqft rectangle.
The underlay will be 100% Grace Ice and Water Shield.
The tiles will be mounted to battens.
Battens will be 1x4 pressure treated wood, with all fixings made from stainless steel.
2 layers of Ice and Water Shield will be at eves and gabels, with metal gabel end flashing and eve drip edge sandwitched between the two layers.
Any repairs to the roof would be complex because of the mixture of concrete tile and solar tile, so it is important to get it right first time.
Is it worth using 2 layers of Ice and Water Shield across the whole roof surface?
I am having a hard time deciding between using elevated battens or counter battens. Both will give me the air flow that I need under the tiles and allow water shed. What are the pros and cons of counter battens vs elevated battens. As I see it:
Counter battens might protect from water penetration a little more, but allow a little less air flow and use more matterial.
If I use elevated battens the elevators will be made from small sections of 1x4 pressure treated lumber, with a nail driven through the batten elevator deck and into the beams.
Grace advise to use smooth shank hand driven nails with Ice and Water Shield to get the best sealing. But ring shank nails have greater wind resistence (higher pull out force) and a nail gun is so much faster! What are peoples’ experiences?
Is it good to use a liquid sealer even when using Ice and Water Shield?
There will be a ridge vent cut in the attic. I want the air from under to tiles to vent. If I rely on natural convection (no fans) is there a risk of hot air from under the tiles getting into the attic, or vice versa. The plan is for hot air from the attic and hot air from under the tiles to both vent to the atomosphere.
There will be a parameter of concrete tiles around the solar tiles. One area of concrete tiles will be a natural place to walk. The tiles are standard weight. I plan to fill the void under two columns of concrete tiles with Great Stuff expanding foam (probably the pro version since it has lower application temperature). Any comments?
If you have good advice on only one of these issues please post a reply.
thanks in advance.