Answers

Question

Geoff Graham of Ken Thieneman Builder Inc. ^PRO asked:

Mar 25, 2019

What is the minimum pitch for a slate roof?

I'm contemplating a slate roof for the new building. The main structure's roof is 8:12, and I'd like to continue with slate for the porches, which will have a much shallower pitch. The building will be in the Western North Carolina mountains in an area that gets regular snow (less than a foot each snowfall, and generally under six inches) and above average rain (about 70 inches per year). Is 3:12 adequate?

Exterior construction & repair, Exterior remodel

Answer 1

John Peil of JPS Roofing Solutions ^PRO answered:

Mar 27, 2019

The minimum pitch for an asphalt roof for Asphalt shingles is 2/12 or more as long as you use at least one layer of ice and water shield and one layer of synthethic felt under the architectural shingles. I would never use a three tab shingle on this low pitch roof. Below 2/12 pitch, I would use either an EDPM Membrane or the Resisto 2 0r 3 ply roll roofing membrane system.