Poor Ventilation???

[Mark P]

I thought this roof interesting. It was not the house I was inspecting, but across the way. What do you think the cause no lower vents?

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[kurt]

Nah. It's been established that vents don't do anything to extend roof life. The single characteristic that has the most effect is shingle color.

The lower shingles are black, the upper are white (-ish). The black shingles are falling apart, the white one's are ok.

[Mark P]

The lower shingles are black, the upper are white (-ish). The black shingles are falling apart, the white one's are ok.

Yes Kurt I realize that. I find it interesting that the advanced deterioration is so precisely defined along the course of shingles that corresponds to about where the attic floor starts. I think ventilation played a role in this pattern of deterioration and it was not just by chance the shingles aged this way.

[Bill Kibbel]

I think ventilation played a role in this pattern of deterioration and it was not just by chance the shingles aged this way.

If it was caused by lack of ventilation, the shingles over where the roof extends beyond the gable-end wall would not have the granule loss.

[Marc]

A fire in the attic? Shingles were still young so they didn't want to pay to re-shingle the entire roof surface. Or the insurance was finicky.

Marc

[Stephen Lagueux]

Nah. It's been established that vents don't do anything to extend roof life.

I guess it's all in the wording. You are right when saying ventilation won't EXTEND roof life. According to my sources, ventilation will help PREVENT premature deterioration of the shingles.

Unless the following 2 groups are wrong, I would love to be pointed to the right direction so I could learn.

http://www.asphaltroofing.org/sites/def ... acts_0.pdf

http://www.casma.ca/en/bulletin_01.shtml

[kurt]

If it was caused by lack of ventilation, the shingles over where the roof extends beyond the gable-end wall would not have the granule loss.

Yes. Attributing it to lack of ventilation is a red herring. It could have been a lousy pack of shingles; that bad patch looks like (about) a shingle pack size. Coulda been a lot of things.

Probably not much to do with ventilation, though. Joe L. has run the numbers on actual temperature differences provided by various ventilation practices, and temps are not hugely effected by ventilation.

[kurt]

I guess it's all in the wording. You are right when saying ventilation won't EXTEND roof life. According to my sources, ventilation will help PREVENT premature deterioration of the shingles.

Unless the following 2 groups are wrong, I would love to be pointed to the right direction so I could learn.

http://www.asphaltroofing.org/sites/def ... acts_0.pdf

http://www.casma.ca/en/bulletin_01.shtml

Both studies are manufacturers and industry folks. They've hung on to all sorts of code stuff that we know is wrong. This isn't a battle I'd hang the war on, but my own experience and half assed experiments show it's all about shingle color, not ventilation.

[John Kogel]

Huh? I see a bad batch of shingles, followed by a batch of better shingles.

[Jim Baird]

I see a cheapskate repair job that left a lot of shingles that shouldna' been left.

[Jim Katen]

Either what John or Jim said and I'm much more partial to Jim's explanation.

There's no way that the roof would have behaved like if all of the shingles were the same type and age and simply exposed to different amounts of ventilation.

[inspector57]

Either what John or Jim said and I'm much more partial to Jim's explanation.

There's no way that the roof would have behaved like if all of the shingles were the same type and age and simply exposed to different amounts of ventilation.

Yep, looks to correspond to different shingle batches.

It may also be age related with the deteriorated shingles older than the rest.

The ones under the tree also look better, maybe the shading of the tree reduced the UV effect.

I typically see more wind damage in the upper third or so of roofs.

We get lots of wind from thunderstorms, micro bursts, straight line winds, etc. that gets lots of shingle damage.

Insurance companies don't pay well for spot damage and I could easily believe the newer shingles were all they would pay for to repair the wind damage.

[Mark P]

I just found it interesting - I'll go play by myself now.

[hausdok]

The pattern behind the tree tells you what's going on. The shelter from that tree slowed down deterioration where the tree was shaded but the entire roof was long past end of service life anyway. They probably had a good wind storm strip off a whole bunch of shingles and the owner, obviously a cheap SOB who probably never replaces a roof until it starts leaking faster than he/she can dump the pots catching the water, based on the condition of the lower part of that roof, only replaced what needed to be replaced to stop any leaks. It's probably just coincidence that it corresponds to the attic floor height.

Don't totally rule out ventilation issues though. Ventilation is more about removing moisture than it is about lowering surface temps. Combine a humidity filled home with a poorly ventilated attic and one sees lots of stuff happening above the second floor ceilings that doesn't happen lower down - paint blistering off all the way down to the wood - sometimes filled with water, warped siding, weeping underlayment, etc. If that humidity moving up and outward can cause those issues to the walls of a house why can't it affect a roof cover in similar fashion?

Owner is still a cheap SOB.

ONE TEAM - ONE FIGHT!!!

Mike