I installed these shingles about fifteen years ago. My roof has absolutely no ventilation underneath because it is a century old house and has solid wood soffits, not perforated. So I added the nine vents you see and figured that hot air would escape out of the four top vents and cool air will flow in through the bottom five. This part of the roof faces south.
Obviously it did not work. Why? I am curious as to what is wrong with my reasoning. Also, if you notice, the shingles at and above the upper vents have not deteriorated, which is the exact opposite of what I was expecting. Strange.
I am redoing the shingles and plan to eliminate most of the vents, perhaps just leave a couple of the top ones.
Roof Shingles Deteriorating From Poor Ventilation?
- Thread starter George7941
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I installed these shingles about fifteen years ago. My roof has absolutely no ventilation underneath because it is a century old house and has solid wood soffits, not perforated. So I added the nine vents you see and figured that hot air would escape out of the four top vents and cool air will flow in through the bottom five. This part of the roof faces south.
Obviously it did not work. Why? I am curious as to what is wrong with my reasoning. Also, if you notice, the shingles at and above the upper vents have not deteriorated, which is the exact opposite of what I was expecting. Strange.
I am redoing the shingles and plan to eliminate most of the vents, perhaps just leave a couple of the top ones.See http://www.certainteedshinglesettlement.com/identifyshingles.cfm
Do not remove the vents. If you want a really durable roof, look at standing seam steel.
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4WD
$50 site donor 2023
Needs intake of cooler air - either vent skin or soffit vents ...
It needs to take air from a shaded area - not where the sun beats down ...
My shingles are organic but not Certainteed, they are IKO shingles.
Also, since the shingles at the top have not deteriorated, it looks like the issue is not with the quality of the shingles.
4WD
$50 site donor 2023
What about your wall construction ? Is there air intake at the base (of exterior wall) that flows into the attic ?
I had my roof reshingled in 1997 with "20 year" shingles. The year before I had a powered roof ventilator installed near the ridge line. It has a thermostat to turn it on when the temp inside is over 130 degrees. A recent roof inspection said the roof is in excellent shape. Static vents don't seem to do much, you need something to either push or pull the air out.
Originally Posted By: 4WD
What about your wall construction ? Is there air intake at the base (of exterior wall) that flows into the attic ?
4WD
$50 site donor 2023
Are you able to add soffit vents ? - no matter if you use those box vents, ridge vents, or even power vents - need intake of cooler air (just a little cooler matters) to generate the thermal flow ...
My house is semi-detached, so the part on the left is my neighbour's roof. His shingles are much newer, so there is no way to compare. I do think my shingles would have not deteriorated so badly had I not added the vents.
The flat part of the roof actually peaks in the middle, at the dividing wall between the two houses, so the roof slopes from left to right. That is why the seams run the way they are. It is not rolled roofing but torch down membrane. It has survived very well and I am quite proud of my handiwork, considering it was the first time I had handled torch down membranes.
My house is the one at the bottom of the picture and you can see the v-shaped wood soffit. I really have not examined it closely but I doubt there is much space between the soffit and the roof sheathing. I will go into the attic and take a closer look.
The bottom row of vents was my effort to provide cooler air. Someone mentioned that that part of the roof is hot, but the ambient air there is free flowing and somewhat cool and not superheated like in an attic.If the roof is packed with insulation, the air cannot flow. There needs to be a vent channel between the insulation and underside of roof deck. Formed styrofoam channels are made to staple under the deck to provide air flow and keep the insulation away from the deck. Air should enter low at the eves and exit at the ridge.
You need to call a professional in order to really determine what is going on. Someone who knows roofing systems and can get up in the attic and assess the problems. Anything here is simply speculation. It's clear they are getting way too hot, and it's clear that the DIY venting system you tried to put in place failed miserably. Heat rises, and your DIY venting system doesn't create air circulation from rising air currents (that's why venting should start at the soffits that face down). Given what
I can make some guesses, but without actually getting eyes on the situation that's all it would be. You also need to get someone in that attic space to look for mold or other issues that your DIY roofing has caused.
That simply isn't correct. Improperly done static vents don't do much (as noted in the original poster's pictures), but properly done static venting works quite well. Our roof is 21 years old and the 50 year warranty shingles still look like new.
Originally Posted By: Piston_slap
Static vents don't seem to do much, you need something to either push or pull the air out.
I've sold shingles since 2000 but have never seen a failure like that! Where I live it's hot and dry and we don't use 3-tab or organic shingles so I might be on the wrong track but... If this wasn't a flat out failure I'd think this was due to cold rather that hot. Is your attic hot it the winter? Do you have ice on the ridge only? You might be heating them from the bottom while they are exposed to freezing air on the outside. Take pictures of the roof with frost and you can see exactly where heat is. Materials in general like to be hot or cold but not hot and cold at the same time.
I keep my house pretty cool in the winter, at about 16C/61F. I am the only one in the house. I don't think my attic gets hot in the winter. I have never had ice dams on the roof.
Originally Posted By: bugeye
If the roof is packed with insulation, the air cannot flow. There needs to be a vent channel between the insulation and underside of roof deck. Formed styrofoam channels are made to staple under the deck to provide air flow and keep the insulation away from the deck. Air should enter low at the eves and exit at the ridge.
Rent a thermal camera in the winter and you will see exactly what is going on.
4WD
$50 site donor 2023
That is exactly how my patio roof works - it has endless soffit vent (perfs) and then flows into the attic - then under the radiant barrier - then out of the ridge vents.
The two roof pitches look like mine - only composite shingles cover both with synthetic under layer.
JHZR2
Staff member
I agree with Pop. You need to get a pro in there, and assess properly. Given your latitude and the look of things, I'd have to wonder if the lifting and damage was due to ice, not heat.
Where are the images from the inside?
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