best for low pitch roofs
I have an older house near Pittsburgh and we need to redo the entire roof. The front is a steep pitch but due to a remodel by the former owner the back is a low pitch, according to one roofer who has given us an estimate. He told us that if the pitch is less than 4:12, a conventional roof using asphalt shingles over felt with drip edges and ice barriers under the first 3 feet up from the low edge won't provide sufficient protection for leaks and he seemed to at least hint he wouldn't give us a guarantee if we told him that's what we wanted.
He recommended something called flintboard made by certainteed for the back side of our house. As a compromise, he said if we didn't want to do that, he would at least recommend ice barrier under the entire back side (the low pitch side), instead of just the customary first 3'.
Is he blowing smoke at me or is he on the level (even if my roof isn't?!)
I've looked at the flintboard stuff on the certainteed home page and even though I'm an engineer with 40 years' experience managing large complex engr/construction fixed price projects I can't tell if this guy is giving me straight dope or not.
I don't know anything about the flintboard, but he is correct about the I&W. As long as it's not surrounded by trees or has no way of drying, it will be fine with I&W on the whole thing and shingles.
Some of the other pro's here may have suggestions for low slope stuff. I don't do alot of it. Have used torchdown before and rubber with good results, and have heard good things about peel n' stick stuff from GAF. No first hand knowledge with the GAF stuff though.
He's not blowing smoke, but he may be a little inexperienced with low slopes if he's never installed shingles on a 4/12,
I have worked in the Pittsburgh area many of times and there are homes in that area in which the entire roof is 4/12 pitch just like here in Youngstown.
On a 3/12 pitch we would install i&w the entire way,
a 4/12 we run 6' high off the eaves in valley's and around all penetrations.
"Absolutely never hire some one who won't guarantee their work, no matter what the reason"
He could be referring to the fact that the shingles on the flatter '4/12' section will not offer the same life span as the shingles on the steeper front side, flatter slopes never last as long as steeper, in that case both
Certainteed and GAF's low sloped solutions seem to be the better deals and either will give you a life span closer to that of the shingles on the steeper side..
Coupla things in reply:
First, thanks for the feedback I got from you both. It helps.
2. I measured the pitch, roughly, from the ground, using simple things like a horizontal measurement I could take from the ground combined with measuring on the ground the height of the number of pieces of horizontal siding it appeared to take to go up to the peak of the low pitch part of my roof, etc. Using that rough technique, I believe the pitch of the low part is steeper than 2:12 but less than 3:12. Definitely not as steep as 4:12.
3. MJW, you remind me of a factor I failed to mention. Our lot IS surrounded entirely by large oak trees. Our entire house is almost always in nearly full shade. We know from the appearance of the roof that it does have trouble drying; moss growing under low hanging branches, etc. So that factor could influence our choice of product, I guess; I'm just not sure what it suggests I should consider!
4. Fox, your comments about how the one roofer I spoke of discussed the issue of guarantee are spot on. In fact, now that I think about what he said, I do think that in fact he was saying exactly what you said: the mfg's guarantees depend on what's used in what circumstances, and that's all he was summarizing to me. I do NOT believe he was raising a red flag with respect to his own work, and I appreciate your insight on that issue!
So, all that having been said, IS a conventional shingle roof using ice and water protection all the way to the peak on the low pitch side and just 3' up on the two parts of the roof that are 4:12 or steeper going to be sufficient?
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