Odd shingle failure

[Marc]

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This is an upscale 16 yr old house with laminated shingles, likely 30 year or heavier. I can't figure this failure mode unless it's a manufacturer defect. Seller's getting a little heated over my recommendation to replace it, especially since it looks normal from the ground.

It's a blotchy kind of granule loss with what I think might be hollow cavities behind the surface of the shingle.

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Marc

[Ben H]

Is the whole roof like that or just a few spots?

[Marc]

It was pervasive throughout the few roof surfaces that I was able to mount. Most of the roof was greater than 12/12.

Marc

[mgbinspect]

I'd suspect under-ventilation. Huge attics typically do very well, but hip roof systems are notoriously under-ventilated - plenty of soffit ventilation, but not enough ridge or roof vents toward the top. Is there a fan, and is it working?

You might remember last year when I had an attic with a hip roof with temps in the 165 range.

The shingles look like they're getting cooked.

[Mark P]

Looks sorta like 'roof blisters" I've seen on 3-tab shingles, but maybe these are bigger There have been some discussions here on "roof blisters". I'd also look at ventulation. Regardless the shingles have more life behind it then in front of it.

[Jim Katen]

Possibly rash blisters.

Have you considered hail damage, though?

[Marc]

Possibly rash blisters.

Have you considered hail damage, though?

No, but hail occurs less than once per decade here. I've seen it twice since I was a teenager. I'll google rash blisters.

Mike B, this house has several attics. A couple were no longer accessible because of ill conceived DIY 'projects' that converted some portions of attic space into conditioned (or semi-conditioned) space and left the balance of that attic space unaccessible. You may be onto something.

Marc

[Chad Fabry]

When I saw the title I was super excited because I racked my brain trying to figure out what would affect only every other shingle. A prime number conspiracist? An OCD roofer compelled to nail only even shingles? Imagine my dismay to discover an ordinary case of IKO disease.

Roof blister/ rash blister. Defect. Around here IKO's are famous for the issue.

With all this talk about blisters I bet this thread comes up in Herpes searches.

[Ben H]

Possibly rash blisters.

Have you considered hail damage, though?

No, but hail occurs less than once per decade here. I've seen it twice since I was a teenager. I'll google rash blisters.

Mike B, this house has several attics. A couple were no longer accessible because of ill conceived DIY 'projects' that converted some portions of attic space into conditioned (or semi-conditioned) space and left the balance of that attic space unaccessible. You may be onto something.

Marc

Seems like 95% of the attics converted into living space I see always have the insulation stuffed against the sheathing with no gap for air. Plenty of soffit vents, with no where to go.

[Marc]

When I saw the title I was super excited because I racked my brain trying to figure out what would affect only every other shingle. A prime number conspiracist? An OCD roofer compelled to nail only even shingles? Imagine my dismay to discover an ordinary case of IKO disease.

Roof blister/ rash blister. Defect. Around here IKO's are famous for the issue.

With all this talk about blisters I bet this thread comes up in Herpes searches.

Thanks for the info. Nice bedside manner BTW.[]

A distributor search at the IKO site yields nothing within a 100 mile distance which is as far as their search function will go. I've never seen a bundle with the IKO name on it. I don't think they've ever been here. Bust this myth.

Marc

[mgbinspect]

Possibly rash blisters.

Have you considered hail damage, though?

No, but hail occurs less than once per decade here. I've seen it twice since I was a teenager. I'll google rash blisters.

Mike B, this house has several attics. A couple were no longer accessible because of ill conceived DIY 'projects' that converted some portions of attic space into conditioned (or semi-conditioned) space and left the balance of that attic space unaccessible. You may be onto something.

Marc

Yeah, well converting attic space to finished space without throwing baffles in will fry a roof too. It could always be a materials defect exacerbated by under-ventillation.

[Jim Katen]

It's not limited to IKO. I've seen it happen on Pabco, Malarkey, Certainteed, and GAF. I suspect that every manufacturer turns out a batch now & then.

BTW, I'm not at all convinced that lack of ventilation or stuffing insulation against the underside of a roof makes an appreciable difference to the temperature. Experiments that I've done on my own house bear that out as do the odd experiments done by others.

There are good reasons to ventilate the spaces under roofs, but keeping the shingles cooler isn't one of them.

[mgbinspect]

When in doubt, get the materials sales rep out. That's typically a highly educational exercise. I used to do it often with masonry materials, and sometimes the big wigs would show up.

[mgbinspect]

It's not limited to IKO. I've seen it happen on Pabco, Malarkey, Certainteed, and GAF. I suspect that every manufacturer turns out a batch now & then.

BTW, I'm not at all convinced that lack of ventilation or stuffing insulation against the underside of a roof makes an appreciable difference to the temperature. Experiments that I've done on my own house bear that out as do the odd experiments done by others.

There are good reasons to ventilate the spaces under roofs, but keeping the shingles cooler isn't one of them.

(I realize there's some truth in what you're saying, since they've started applying expandable foam to the backside of roof sheathing. I'm stiill scratching my head on that one...)

[Jim Baird]

That chimbley column looks mighty short.

Beside the point, but I wonder if any where in the report the word "ugly" popped up?

[Marc]

That chimbley column looks mighty short.

Beside the point, but I wonder if any where in the report the word "ugly" popped up?

No. What is it that seems ugly?

Marc

[Richard Moore]

I wouldn't go so far as to call it ugly, but the large, plain roof does make it look like a glorified Pizza Hut sign. It needs some details...

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[John Kogel]

I wouldn't go so far as to call it ugly, but the large, plain roof does make it look like a glorified Pizza Hut sign. It needs some details...

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Nice work, Richard. I thought I was looking at Marc's pic, then I flipped back to his post. Wow.

You've fixed the attic venting, too.

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[inspector57]

I'm betting on moisture blisters from a manufacturing defect or improper storage.