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only 9 years and this?


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Just about every 3 tab made in the last 15 years does that, it's how they keep them under $100 a square.

I see lots of cheap 3 tab shingles around here that do not have that issue. They wear out at around 13-15 years unless hail or wind gets them first but cracking like that does not happen unless it is a manufacturer defect. Lack of ventilation will be blamed but I rarely see shingle problems on HOT, HOT attics with little to no ventilation. Defects seem to be equally distributed among both houses with good and bad ventilation. I'm not saying ventilation has no effect but I think it is more of a cop out for shingle manufacturers than an actual verifiable reason.

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The claims-guy up here at the roofing manufacturing plant in the next town over calls that 'cracking in the applique' (versus "cracking thru the fiberglass-mat") and says 'it's not a defect that leads to leakage.. "..

Some kind of crazing/shrinkage in the asphalt on the reinforcement .. I guess...

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Yes. It's cracking in the bitumen application, not the mat. I see it all the time, and I've never seen it cause any particular problem. My take is it's the downgrading of the bitumen due to environmental regulations and manufacturer processes to decrease cost. If one has ever seen and smelled an old (like from the early 20th century) coal tar pitch roof system, one knows it's something different from todays materials. I could be wrong on that last bit; it's just my WAG.

It's not ventilation because it's well established that vents do nothing to reduce roof covering or attic temperatures. Ventilation is about condensation and moisture issues, re: Joe L.

And the whole thing with statistical lifespans........

There's no such thing. Roofing performs as well as it drains. I actually saw a 67 year old roof last Spring; it was on one of those English Cottagey type designs with roof pitches that were about 20:12.

There is no reliable data for declaring statistical lifespans. All the statistical lifespan charts one sees are pulled from other charts pulled from other charts ad infinitum....if one followed the path, it would probably end up at the first chart.

There is something called a probability distribution, based on analysis of multiple random variables. What we do is based in random variable analysis, although that idea is disputed by most HI's. Most HI's like stat charts.

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Just did a quick look-up in my Haag Engineering guides. Below is their comment for such defects:

"Manufacturing Issue:

Craze cracks, due to shrinkage and embrittlement of unreinforced asphalt only in the "applique" portion of a shingle.

The applique is an extra layer of asphalt and granules added on top of the original layer of asphalt and granules to make a three-tab shingle look like a laminated shingle."

Above is a direct quote from their Composition Roofs Damage Assessment Field Guide.

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It's not ventilation because it's well established that vents do nothing to reduce roof covering or attic temperatures. Ventilation is about condensation and moisture issues, re: Joe L.

It does in my area. In extreme cases involving low attics it's a definite factor in the life span of a shingle covering. A lack of ventilation in low attics can also result in longitudinal cracking of structural wood members. I see it with my own eyes every once in a while.

Marc

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Jerry and Marc, go to Joe. Read up.

Wood cracking? Of course wood cracks in a hot attic. But, venting the attic makes little to no difference in attic temperature, and it doesn't make shingles fail.

UV makes shingles fail. Other things might make them fail. But, hot attics do not make them fail.

Physics indicates a few roof vents cooling an attic is not possible, at least according to Joe.

Argue with Joe, not me. I'm just the messenger.

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Just did a quick look-up in my Haag Engineering guides. Below is their comment for such defects:

"Manufacturing Issue:

Craze cracks, due to shrinkage and embrittlement of unreinforced asphalt only in the "applique" portion of a shingle.

The applique is an extra layer of asphalt and granules added on top of the original layer of asphalt and granules to make a three-tab shingle look like a laminated shingle."

Above is a direct quote from their Composition Roofs Damage Assessment Field Guide.

I've seen that type of layered 3 tab shingled before. That's not was I was looking at in this case.

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Addendum....

I can't find the link to the study, but there's a fair amount of credible evidence to show that one of the critical factors in shingle lifespan is color.

White shingles last longer than black ones, for the obvious heat retention characteristics.

Also, angle of the roof, i.e., is the sun beating down on it at 90deg, or is it an oblique angle. That might explain Marc's experience with "low attics".

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That's a good one, but that's not the one I read recently. I think it's one of his InSights where he flat out says roof vents don't do anything to reduce attic temps; the physics of trying to cool a couple thousand square feet of sun blasted roof with a few square feet of ventilation just doesn't add up.

A quote taken from your link though.....highlighting is mine....

"All other things being equal, applying the Arrhenius equation (Cash et.al, 2005), a 10 percent reduction in useful service life should be expected. This is comparable to the effect of the installation of radiant barriers. What is more significant to note is that the color of shingles and roof orientation have a more profound effect on the durability of shingles than the choice of venting or not venting (Rose, 1991) ? double or triple the effect of venting/non venting."

Where this plugs in most significantly is useful life expectancy. These are some of the random variables I was talking about that effect lifespan.

And, I think William B. Rose's work is where I first read about this stuff. He was getting it all right >20 years ago.

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Also, angle of the roof, i.e., is the sun beating down on it at 90deg, or is it an oblique angle. That might explain Marc's experience with "low attics".

That's more a factor in shingle temperature though it affects attic temps also.

Look at it this way: A natural draft water heater needs a flue of a minimum vertical feet to accomplish a draft. The vertical height of the flue pipe and the heated air work together to move air upwards. Consider a low attic as a short flue pipe, it doesn't have enough height to take advantage of the ventilation openings and heated air to get air to pass through it.

Marc

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Yes. It's cracking in the bitumen application, not the mat. I see it all the time, and I've never seen it cause any particular problem. My take is it's the downgrading of the bitumen due to environmental regulations and manufacturer processes to decrease cost. If one has ever seen and smelled an old (like from the early 20th century) coal tar pitch roof system, one knows it's something different from todays materials. I could be wrong on that last bit; it's just my WAG.

It's not ventilation because it's well established that vents do nothing to reduce roof covering or attic temperatures. Ventilation is about condensation and moisture issues, re: Joe L.

And the whole thing with statistical lifespans........

There's no such thing. Roofing performs as well as it drains. I actually saw a 67 year old roof last Spring; it was on one of those English Cottagey type designs with roof pitches that were about 20:12.

There is no reliable data for declaring statistical lifespans. All the statistical lifespan charts one sees are pulled from other charts pulled from other charts ad infinitum....if one followed the path, it would probably end up at the first chart.

There is something called a probability distribution, based on analysis of multiple random variables. What we do is based in random variable analysis, although that idea is disputed by most HI's. Most HI's like stat charts.

Kurt,

I have a real problem with quantum mechanics too.

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For those who think that lack of ventilation has a profound effect on shingle life, why is it that shingles installed over wide eaves and overhangs don't last longer than shingles on the unvented portions of the very same roof?

It's not a profound difference.

As for why eaves shingles don't age as fast, who's looking? There isn't much difference to see.

The worst cases will have about 2 to 4 years taken off the life of 3-tab shingles. 19 years for 12/12 pitch, high attic. 15 to 18 years for 4/12 and an attic about 2 or 3 feet high. Or thereabouts. It's anecdotal.

Marc

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