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Confusion Over Shingle Warranty

In the item about shingle warranties with unvented roofs (Q&A, 1/10), the first sentence clearly states that GAF’s warranty is still valid when the shingles are installed over a roof deck insulated with SPF foam. But later on in the same response, the author says, “since GAF-Elk does not supply the sprayed-in-place foam insulation, any damage to our shingles — or any other roof-related problems attributable either to sprayed-in-place insulation applied to the roof deck or to a lack of ventilation — is not covered by the terms of our warranty.”

What kind of double-speak is this? I’ve read the response over and over again, and I still don’t know if the company covers the shingles or not.

Rob Knorr Nordic Construction Pound Ridge, N.Y.

I wanted to comment on the shingle warranty Q&A. I love how a manufacturer will, in the same answer, say, “GAF-Elk’s shingle warranty is still valid when the shingles are installed over a roof deck insulated with SPF foam,” and then, “since GAF-Elk does not supply the sprayed-in-place foam insulation, any damage to our shingles — or any other roof-related problems attributable either to sprayed-in-place insulation applied to the roof deck or to a lack of ventilation — is not covered by the terms of our warranty.” I read the response very slowly three times in order to believe what I was reading; I would appreciate it if JLC would screen such nonsensical answers.

I’m also unclear what he means by, “The issue ... is that the insulation can retard or block moisture-vapor migration through the roof assembly, where it can then condense in the framing, sheathing, and insulation.” If the insulation blocks moisture, how can that moisture then condense? The shingles have nothing to do with condensation caused by interior vapor drive, so why mention it?

Mr. Woodring does not allude to another problem, which is that shingles can curl prematurely — or worse, in hot climates — on an unvented roof, especially on the south aspect.

Jim Olson Viroqua, Wis.

Q&A author Bill Woodring, director of technical services at GAF Materials, responds:GAF/Elk’s limited shingle warranty covers manufacturing defects in the shingles and remains valid if the shingles are installed over a roof deck insulated with SPF. The warranty does not cover everything that can go wrong in the roof system.

It’s like a tire warranty: If the front end of your car is out of alignment and the tire wears out prematurely and fails because of the misalignment, the tire manufacturer will not pay for the new tire. However, if there were a manufacturing defect in the tire that caused the tire to fail, this would be covered by the manufacturer’s warranty. Likewise, if an issue develops with the decking or substructure that causes the roof to leak or the shingles to fail, this would not be a shingle manufacturing defect and would not be covered.In answer to Mr. Olson’s concerns, spray foam insulation will retard moisture-vapor movement to varying degrees depending on the foam. However, condensation can occur within the insulation and roof assembly. That’s why I recommended that the designer or specifier run dew-point calculations when using spray foam insulation underneath the roof deck to confirm that the proposed roof assembly will not have a condensation issue.As for premature curling of shingles, this can occur with an unvented roof assembly, but historically it’s been an issue with organic-felt asphalt shingles rather than with glass-mat asphalt shingles.


Low-Flow Caution

Regarding the story by Leigh Marymor on high-efficiency toilets (3/10), I agree that less is better, most of the time. However, low-flow toilets can create a problem when they are not used often; this can happen, for example, if you have three people living in a three-bath house. Given intermittent use, if the drainpipe to the septic system is long, matter dries in the pipe and clogs things up because there isn’t enough flow to move the material downstream. Testing to see if the bowl stays clean or how well matter makes it through the toilet is only part of the picture.

Jeffrey Price, Esq. Gainesville, Fla.