How to chose the right roofing product

rturner1 · 04-09-2013, 07:24 PM

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, 07:45 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, 08:30 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, 08:46 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.
http://www.bing.com/images/search?q=...ectedIndex=116

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

GBrackins · 04-09-2013, 09:06 PM

Quote:

Originally Posted by rturner1

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!

jagans · 04-09-2013, 09:39 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

04-09-2013, 07:24 PM	#1
rturner1 Newbie Join Date: Apr 2013 Location: Northern CA, northwest of Sacramento Posts: 1	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.

04-09-2013, 07:45 PM	#2
joecaption Member Join Date: Nov 2011 Location: Hartfield VA Posts: 18,821	How to chose the right roofing product 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). __________________ Please edit your profile so it shows your location! No one here knows exactly where on the planet you may be so how can we ansewer a code, building, or insulation question without it?

04-09-2013, 08:30 PM	#3
PatChap Member Join Date: Nov 2012 Location: Hamilton, Ontario Posts: 69	How to chose the right roofing product 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.

04-09-2013, 08:46 PM	#4
joecaption Member Join Date: Nov 2011 Location: Hartfield VA Posts: 18,821	How to chose the right roofing product 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. http://www.bing.com/images/search?q=...ectedIndex=116 Some roofers try to bend the shingles over the break, huge mistake. The shingles will crack everytime. __________________ Please edit your profile so it shows your location! No one here knows exactly where on the planet you may be so how can we ansewer a code, building, or insulation question without it?

04-09-2013, 09:39 PM	#6
jagans Roofmaster Join Date: Oct 2012 Location: Maryland Posts: 3,145	How to chose the right roofing product 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 __________________ " A lot of men build things, and a lot of things fall down "

How to chose the right roofing product