I’m stumped on this one. Yesterday I looked at a two story house where the owner, among other things, noted buckling roof shingles and black stains under the roof sheathing.
Easy, I figured. Not enough insulation and/or air sealing in the insulated attic floor, and probably no soffit or ridge vents.
Well, there are propa-vents, leading to vented vinyl soffits, and there is a properly installed ridge vent. The attic floor had additional joists to raise the floor level enough for 8-10″ of blown fiberglass on top of the original 6-8″ of fiberglass batts. There is probably not enough air-sealing, and an insulated air duct runs through the space, but it looked about as well done as I’ve seen.
The owner had a fan installed in a gable end vent, wired to a humidistat set to turn the fan on when the humidity reached 35° or so.
So the question is, why is the roof sheathing black, and why are the shingles buckling?
Replies
It's black from mold - probably the most on the north side -- probably above kitchen and/or bath areas.
I'd look for (a) a very damp craw space/basement (b) waste vents discharging in the attic (under the aded insul?)
Unless there are really great reasons to buy, I'd shy away from a resale point of view. That's a subjective view.
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Bob, to keep things short I left out:
Very nice dry full basement.
South side (pictured) and north side appear to have equal amounts of mold/mildew. Kitchen is two floors below.
I'll check on waste vents, didn't think of that one, but the quality of construction looked pretty good up there so I'd be surprised if that was the culprit.
This is a service project for past clients we did a kitchen and bathroom addition for. They're a retired couple, own the house and aren't going anywhere. They just want things fixed, and fixed right. The buckling shingles look weird to me and the roofer (high-end) who looked at another part of the project with me.
You know, you reminded me that after we did the kitchen ten years ago, we remodeled their master bath on the second floor about five years ago. I'll check that we didn't mess up the vent fan there.
Have you seen shingles fail prematurely like this, about ten years into what look like 25yr 3-tabs? Could interior moisture contribute to shingle failure? I suppose if the plywood is saturated it could have delaminated. I'll check on that too.
Don't think it is the source of your problem, But I understood it was a No-No to combine gable vents, especially power vented, with ridge venting.On second thought maybe that is problem. The gable vent is drawing air backwards through the ridge vent and the system is not able to function properly.
TFB (Bill)
That's an interesting thought. There are propa-vents at the eaves to act as insulation baffles, but they don't run all the way up the rafters. Maybe closing the gable vents, leaving the fan off, and allowing the stack effect to do its thing with the propa-vents is the way to go.
sound like gabel fan could be creating negative pressure in the attic to the extent that it is causing tar to diffuse through your ply and quickly killing the shingles. ever heard of that before? curious..."A small leak can sink a great ship."
-Benjamin Franklin-
sound like gabel fan could be creating negative pressure in the attic to the extent that it is causing tar to diffuse through your ply and quickly killing the shingles. ever heard of that before? curious...
Interesting thought, but there are ridge and soffit vents, so I seriously doubt there is any negative pressure involved. It's not that big a fan.
Have certainly heard of 20-25 year shingles failing in less than ten. Just ask thousands of people who got Certainteed shingles some years back in the Midwest.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
Have you seen shingles fail prematurely like this, about ten years into what look like 25yr 3-tabs?
Mike, I have a shingle warranty claim right now I am trying like hell to get the BP rep to come and look at. Been after his invisible arse since October and I'm getting cranky....
Same basic problem--buckling and cupping 25-year 3-tabs after 9 years--but only over one small area of the roof, and it's the porch roof at that (no heated space under it).
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We figure it was a bad lot of shingles; I checked my bills for that job and found we had two batches delivered because of a screw-up in ordering.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
talk w/ the manufacturer, man ... don't guess about what it may or may not be. The manufacturer knows what will cause his product to go bad. At least START there. Without that, you don't have a leg to stand on anyway. Know what will cause the condition and determine if that house has the condition. THEN you can talk about what to do or what MIGHT happen ... talk is cheap ... follow up on it.
talk w/ the manufacturer, man ... don't guess about what it may or may not be. ...At least START there. Without that, you don't have a leg to stand on anyway. ... talk is cheap ... follow up on it.
"I am trying like hell to get the BP rep to come and look at. Been after his invisible arse since October and I'm getting cranky...."
What part of the above extract from my original post did you not understand the first time around??
The rep is hiding. My dealer has 5 unresolved, uninspected (by the mfgr) warranty claims on his desk, and has had some of them there for a year. Mine's been there since last October. The rep has turned into an anwering machine that listens but does not call back.
I went in in person again two weeks ago and witnessed the dealer leave yet another message on the rep's voice mail. Still no answer. If I don't get an inspection sheduled for this week, I'm calling the mfgr's main office direct and am gonna make a very hairy nuisance of myself....
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
That's what I meant, no installer, no local rep ... straight to the manuf. If they have unrealiable people installing or representing their product, maybe they're interested in that fact.
Okay, we misunderstood each other.
The claims weenie at the main office said it would take 4-5 weeks for an inspection; I told him his local rep had already stalled for 7 months so he could stuff that. Sent him some of those pix by e-mail and am supposed to have an answer by next week.
We'll see. I may wind up covering this one outta my own pocket; thank bog it's only a couple of square out of a 10-square job.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
That looks familiar. That's only 9 years old? Wow.
Yeah, I did that job in 2000. It actually looks worse than some parts of a job I did in 95 using el-cheapo 10-year 3-tabs. Weird. The affected area is only about 75-100 sq. ft. You can see by the photo that the rest of the roof is in perfect shape.
This is the only problem I've ever had with BP shingles in over 16 years; I prefer their stuff to IKO as there is better uniformity in cut and colour...but I am getting pretty bent about the damned rep hiding out so he won't have to come up with a lousy four packs of shingles on a 30-square job.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
Check w/ the shingle manufacturer; he will tell you under what kinds of adverse conditions that shingles will fail. It's usually fairly specific if I recall ... like auto mechanics ... not a lot of guess work.
Because it should have been a 'de'humidistat? I'm sure that is what you meant, though. There is a difference and if you assume one is the same as the other ... maybe that IS the problem. Also humidistats/dehumidistats tend to be problematic in that they don't have staying power ... should maintain/replace every few years ... maybe more.
The switch is activated once the humidity reaches a certain level. I've never heard the term "dehumidistat," care to educate me? Is it an "on" switch instead of an "off" switch?
It looks like this: http://www.nextag.com/Honeywell-H46C1166-Humidity-Control-88515317/prices-html
A dehumidistat works just the opposite of a humidistat. I don't recall the details of how they work. A dehumidistat is often used to control e.g. a bathroom fan ... shutting it off when it senses the shower moisture has been removed. We used them often in the pacific NW where controls were required by energy codes. It was one option.
Due to their sensing technologies, humidity sensors are much more prone to failure than e.g. a sensible temperature thermostat. The part that senses humidity is very sensitive and prone to 'fowling' (for lack of a better word). In an attic, it may be much more prone to dust/dirt affecting it ... don't know.
Either way, once the humidity reaches a certain level a switch is activated. I can't see how a humidistat could be that different from a de-humidistat, other than one opens the circuit and the other one closes it. Good tip on the propensity for failure though.
We just discussed it briefly in our office and decided that we will recommend closing off the gable end vents and deactivating the fan, to let the stack effect ventilate the attic. If it doesn't work it can be un-done.
Also leaks in the ducts can be VERY detrimental in terms of pumping unwanted air into the attic. If they aren't sealed, all the insulation in the world won't do them any good.
Also leaks in the ducts can be VERY detrimental in terms of pumping unwanted air into the attic. If they aren't sealed, all the insulation in the world won't do them any good.
Good point, I'll check on that too.