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Cracked defective shingles


Neal Lewis
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Yeah, you're right. They're torn, not cracked, and there are sections like this throughout. No problem with the structure at all.

I see this frequently with older fiberglass strip shingles and with architectural shingles from the 80's. There was the class action lawsuit with GAF Timberline.

But why the heck does it happen, especially in rows?

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After hurricane Hugo in '89, under pressure from the insurance industry, several shingle manufacturers increased the bonding strength of the tab adhesive. With normal expansion and contraction, the shingle mats perform like a single membrane and large tears form.

When many of the tears are vertical, across several courses, it usually indicates the shingles were installed with the vertical joints laddered rather than staggered up the roof.

Also, many three tab shingles back then had very thin mats, that wouldn't meet current tear-resistance requirements.

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It's always been my theory that they glued together too effectively and as the glue lost its resiliency the shingles tore in high stress areas. Whenever I see these tears the roofs are melded together like liberals at a Jesse Jackson rally.

On a hot day the shingles are baking and then a rain contracts the top layers while the 170 degree attic heats the bottom layers creating a differential expansion like a head gasket between an iron block and an aluminum head.

Please, consider the source.

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