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rturner1 04-09-2013 06:24 PM

How to chose the right roofing product
I need to replace the asphalt shingles on my roof. I have a gambrel roof and the roof pitch is 2:12 and 10:12. I want to use a good quality product: a 30 or 40 year roof with an architectural shingle. I currently have a cheap 3 tab shingle; however, because of the rather flat pitch on top, there has been a lot of wind damage (singles being blown off). I got 3 estimates; however, one of the contractors recommended I still use a 3 tab shingle. He believes that because of the steep pitch on part of the roof that the architectural shingles may seperate and slide off if the temperature gets above 100 degrees. It does get above 100 degrees 5 or 6 days each summer and some of the roof faces the southwest. Additionally, I do not have any attic - the roof is 2 X 6 knotty pine, 1 1/2 " of rigid foam, 1/2" plywood, 15 pound felt, and then the shingle.

joecaption 04-09-2013 06:45 PM

Not much of a roofer in my opion if that's what he suggested.
A 12-2 is a bare minium pitch for any shingled roof.
A three tab as you know is not going to work out long term.
Pick a brand of shingle and go on line and look at there install suggestions.
Bet they suggest doubling up on the felt and less exposure on the shingles.
With that low a slope I'd be looking at standing seam metal roofing, EPDM, anything but shingles. (no rolled roofing).

PatChap 04-09-2013 07:30 PM

I agree, anything but shingles on the 2/12, but for the 10/12, that's perfect for shingles
Though if your house is a true gambrel the walls are likely much steeper than 10/12, most I see are around 20/12. Either way, laminated shingles, installed properly will hold up fine, I would require 6 nails per shingle and whatever else is required for the manufacturers high wind spec.

joecaption 04-09-2013 07:46 PM

One trick to make that style roof shingle work out on that style roof is to lower where you nail the shingles so it catches both layers of shingles.
Where the angle breaks I install the shingles as if it's two differant roofs.

On the upper roof I use flashing that bent over the steep part, a starter course, then run the shingles.

Some roofers try to bend the shingles over the break, huge mistake.
The shingles will crack everytime.

GBrackins 04-09-2013 08:06 PM


Originally Posted by rturner1 (Post 1155662)
roof pitch is 2:12

2:12 as mentioned is not the best pitch for a shingle roof. I would recommend covering the sheathing for the 2:12 section with ice and water shield. This should help in the event the wind drives rain under.

as Pat said are you sure on the 10:12 pitch on your gambrel. got any photos you could post?

Good luck! :thumbsup:

jagans 04-09-2013 08:39 PM

2/12 is too low of a slope for asphalt shingles, but Most sheds are not very big. On the low slope area, use double ice dams material, and envelope a metal drip edge at the break, as the other poster recommended. I am pretty sure your slope on the steep area is much more than 10/12 on your gambrel roof. (10/12 is less than 45 degrees.) On the steep area, use 8 nails per shingle and set every tab (low and steep slope) in a dab of elastomeric flashing cement. You should be OK.

Take a look at the Certainteed Landmarks. They would look good on a Gambrel Roof IMHO

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