Post Number: 547
|Posted on Monday, November 22, 2010 - 08:25 pm: ||
S-1 slate is very dense and hard and will not absorb water, so it is not bothered by the freeze thaw cycles. You store it outside in the weather and it doesn't bother it in the pallet, so why would it bother it if applied correctly on a roof?...It doesn't!
A lot of slate has been installed over 3/4 inch plywood, but that is not the ideal substrate. With the good ventilation and the extreme slope involved, I would have no problem at all with the application. Go for it!
Post Number: 1
|Posted on Monday, November 22, 2010 - 02:24 pm: ||
For a few months now I've been enjoying posts and resources from this group and Mr. Jenkins. I'm wondering if there is a limit to slate in areas of +200 days of freeze/thaw cycle. While people on this board mention the issue, I cannot find a definitive post on the topic. Assuming one is prudent in their selection for such a climate, choosing S1 grade with a min 3/8" thickness, what are the general limits?
The example I have in mind assumes a good installation meeting basic criteria such as headlap, flashing, number of nails appropriate to slate thickness, etc. The slope of this example is 60 degrees (roughly 21/12). As I said above the freeze/thaw cycles are intense, but it's a rather dry climate. (rain fall intensity is just over 2, but they get a lot of snow -- roofs to withstand 75 psf) The decking is 3/4" plywood, and the attic is non-conditioned but adequately ventilated.
So far I've heard mostly skeptical remarks, but then again, not from slate experts. I would be grateful for any thoughts on the suitability of slate in this instance.