I’ve got what looks to be a serious problem and need an informed diagnosis.
I’ve been battling squirrels (rats with longer tails) in my gutters for a couple of months. Over the weekend I went up to the attic to see if they had gotten through my last line of defense. While I was up there sweating I found what appears to be a more serious problem.
My 13-year old Craftsman style house seems to have developed some sort of roof or moisture problem. The roof is conventionally framed with 2x6s supporitng OSB. The eaves are fairly wide like many Craftsmans. What I found in the attic were dark stains at the very end of the OSB where it meets the far edge of the soffit. I would normally associate dark stains like this with moisture problems. I have an attic fan that runs regularly and I’m fairly certain high humidity in the attic is not the problem. I’ve attached two photos illustrating the stains (apologies for the scale, but I also can’t figure out how to make the photos smaller before attaching them.)
My 30-year asphalt shingles have never had a problem and there are no visible leaks in the roof. I suppose at this point I’m trying to answer two fairly simple questions: (1) Is the staining on the OSB water damage or could it be from something else? and (2) If it is water damage, where could the water be coming from? The stains appear to be starting at the farthest edge of the eaves, at the very end of the rafter, and working up toward the ridge, but not more than about 18 inches in any location. Also, the stains cover probably 20% of the perimeter of the attic and are not localized.
I’m stumped. Do I have a leaky roof? Ventilation problem? Mold problem?
Any ideas apprecaited.
Replies
First step is to resize these down in size and then repost.
First pict is too fuzzy to determine any thing the second was much better. Still thinking about what I saw.
irfanview is how to resize them, IMHO I think it's water getting back under the shingles, mabey something around the drip edge, probably a reroof is in your future
The next level is here.... Turning.
Hmm. My first thought would be ice damming. Less than stellar roof insulation & wide overhangs is an invitation to freeze-ups and water backing up under the shingles. But, that said, I see you're in Atlanta -- don't imagine ice damming is all that common there?
Mike Hennessy
Pittsburgh, PA -- Where we DO have ice-damming -- or used to before global warming. ;-)
My first thought before seeing photos and his location was the same - ice damns.After thinking of his location, I figured it was poor ventilation allowing condensation at eaves.After seeing the photo, I knowhis insulation is woeful, so a combination of bad venting and lousy insulation seems to be the cause, except that the spot is very contained and limited, looking more like a leak.S I would be checking the roof surface itself
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Thanks for the advice and technical assitance with resizing the photos.
If water is getting back under the shingles, could it wick up as high as the staining? As I said earlier, at some locations the stains are about 18 inches high.
If this is the cause, one explanation could be that the guards covering the gutters are causing water to pool against the roof sheathing. I've got a big oak tree partially shading the house and needed "gutter-guards" to keep debris out of the gutters. I'm not sure what brand of gutter covers I got (10 years ago), but they're the kind that water flows up and over while debris flows up and off. They are plastic and are installed by sliding one edge under the first row of shingles and snapping the outer edge onto the gutter. If water pooled on the guards, it would have fairly easy access to the sheathing.
Has anybody ever heard of gutter guards causing problems like this?
How about some pics of the same area from OUTSIDE the house? That might give us some more clues to work with.As steep as the roof appears to be, I doubt gutter guards would ever back water up.
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I am not familiar with that kind of guard, but gutter guards do often cause problems and I would be very leery of one that required fitting under shingles after the roof is done. I'd be willing to bet that they damaged the roof when they installed these. Like I said, trip up a ladder to see the specific locations where you have water sign is needed.
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My investigation continues and I'm trying to narrow in on an answer. At this point the leading theory seems to be water riding up the gutter guards and getting under the shingles and onto the sheathing. The gutter guards are white plastic and come in 4' sections. I had them all taken off today and inspected them. Because they are white, they show dirt and water streaking pretty clearly. The exposed part (not under the shingle) was dirty with pollen / grit, but the part under the shingle was noticeably whiter. At least 8 or 10 of the guards had streaks that traveled across the under-shingle white part. I can't imagine how streaks like this got there unless water was backing up the to edge of the guard, which would then make contact with the sheathing.
Aside from the fact that I've had the guards on for 10 years and never noticed a problem, the only thing making me question this theory is that upon a closer inspection, the sheathing damage appears to be all the way down one side of the roof. and part of the way down the other side. (My house is in Atlanta on a 50 foot lot; it's about 35 feet wide, but 70 feet deep) This would seem to indicate a more widespread problem like moisture being pulled in from the vents. I have no doubt that humid Atlanta air is being pulled through the attic by the fan, but can the temperature difference of an eave really cause condensation and that much damage? Wouldn't I see water coming back through the soffit vents?
One last question. Which of these for-hire guys is most likely to figure this out for me? A Roofer? Gutter installer? HVAC guy? Home Inspector?
Back to your picture. Am I wrong in not being able to see the ends of roofing nails stick through?
I see the big long guys that were supposed to hold the sheathing down, missing the rafters, but only one or two roofing nails.
Guys, could this be the result of using too short of a nail? Or is there a nailing problem here?
An experienced HI or a general renovation/remodel guy who understands moisture issues.I can't help much without those exterior photos of specific places where you have the water sign.You have said several times that this is all the way along, but the photos from inside show it in more specific spot locations and not generalized all the way along, so we have a problem with terminology. Do you mean several specific spots along the whole eave?And what are those spots relative to on the outside?
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To update my previous posts:
I talked to an old-timer roofer and explained the problem to him and he said he could diagnose it without even seeing it. He said the problem was due to shoddy roof installation when the roof was originally put down. Specifically he said some roofers use "toe-boards" near the eaves when installing roof material. While apparently there are devices to do this without damaging the roof, some guys will just nail the boards through the shingles. This will cause a tiny leak that won't show up for years. According to this roofer, this is most common on steeply pitched roofs like mine. I'm trying to schedule him to come out and confirm this is the cause, but we haven't gotten together yet, and he seems pretty convinced even without seeing it.
Has anyone ever heard of this problem? Any opinions on whether nail holes could cause damage like this? I have crawled up under the eaves from the attic and looked for nail holes but can't find any obvious entry points.
Any opinions on whether nail holes could cause damage like this?
It's a possibility. http://grantlogan.net
.......nature abhors a vacuum cleaner.....
Sounds like quite a stretch to me. I've used those brackets a lot. When I use them, I put a row every 5' or so up the slope of the roof. So if nail holes were the problem, I think there would be other holes as well.
No one ever sat their way to success
very believeable to me. He undoubtedly knows his area and some of the shoddy practices used around there nbetter than we do. I have always used roof jaccks to hold planks up, but I have sometimes seen after I leave a job where painters nail a toeboard on as described. Never seen a roofer do it, but I suppose that haks learn new tricks the rest of us never dream of.
This kindof damage is very similar to what I have seen and had suspected happened with the gutter screens - that poor qwuality installation had included poking some holes in the roof.The fix is fairly easy.
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Around here, the "new construction" roofers nail toe boards thru the shingles frequently. They pick up 2x4's laying around the site vs. re-roofers who have to buy and haul toe boards with them. I usuallly buy PT 2x6 so they last longer.http://grantlogan.net
.......nature abhors a vacuum cleaner.....
hacks
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Hey, I am most definitely not a hack and have done as you describe with one exception. After pulling the board I lift the shingle and put a shot of geocel into the nailhole and then set the shingle back into the caulk. You get a good seal, you can't see it, and it works great on a 7-8/12 where you dont really need a full jack board but it's nice to have something there. Never had a problem.
Just my .02 =)
Naive but refreshing !
Edited 8/5/2008 11:22 pm ET by woody1777
86,
Does your roof have the metal drip edge?
If it does, check under the first course of shingles to see if the felt paper is over or under the metal drip edge at the eaves. Should be over the metal drip edge at the eaves.
If under then any water that gets past the shingle at the edge due to the gutter screens will run behind the drip edge and across the end of the OSB sheathing and be soaked up by the OSB.
Keep in mind that the OSB will wick water uphill quite a distance and from the pics you have posted it appears that the leak is at the roofs edge.
While you are up there check out how the shingles are laid. Do the ends of the shingles in consecutive courses line-up? or every other course?
Are there any valleys involved?
I also do not see enough nails poking through on the bottom side of the decking.
Tell me what you see.............Iron Helix
I also do not see enough nails poking through on the bottom side of the decking.
Yeah - I noticed that as well.http://grantlogan.net
.......now there's a Batman.....
It seems the simplest answers can be the hardest to find.
I had the old-timer roofer I mentioned earlier come out yesterday. He not only confirmed his earlier opinion of the problem as nail holes from a toe-board, but took me up on the roof to show me the holes. They were small, and you wouldn't notice them unless you were looking for them, but they were in a straight line about a foot above the edge of the roof.
It took 13 years for the nail holes to leak enough water for me to notice the rot in the sheathing, but it happened.
Thanks for the help. Time to get on with the repairs.
It isn't the toeboard nailing I have a problem with. It is leaving an ungaurded hole to leak, assuming that it self helas like some do.I prefer to also slide a slip of metal in where the hole is, under the shingle in addition to the dab of geocell.Just yesterday, I had to mount some roof jacks on the surface to provide access for somebody. When I remove them, I will be sliding metal up under and caulking it too.In most cases, your dab'o'Geo trick will do it. with low slope and snow build, I would expect that it would not last as long as the shingles tho. 'course, you don't need the toeboard with low slope - unless you are a painter.
;)
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I will be sliding metal up under and caulking it too.
My prefered method is to lift the shingle and squirt a little Geocel under and then drive a sliver of shingle down into the hole. If the caulk squirts up thru the hole, you can sometimes spot it shining from the ground. The sliver trick is about impossible to spot. If the shingles are well sealed and there's a risk of tearing them if I try to pull them apart, I just drive the sliver in, especially on steep roofs. http://grantlogan.net
.......now there's a Batman.....
Why do I only see a few roofing nails coming thru? Where's the rest of them?
"except that the spot is very contained and limited, looking more like a leak."
I thought that at first, but then I think the photos showed the damage in more than one bay. Maybe a bath fan vented into the space?
OP: Leaf guards could easily cause this if you lack ice & water shield and the clogged guards (which cause more problems than they solve, IMHO) backed water up onto the roof. Or, as Piffin observes, it could be water vapor condensing on the underside of the sheathing near the cooler (due to eve vents) edges of the roof. Look for sources of water vapor (like a bath or kitchen fan vented into the space) and check the underside of the sheathing some cool morning.
Mike HennessyPittsburgh, PA
Do you run the attic fan when it's raining? Could it be pulling rain in?
The attic fan is on a thermostat, so it would run during rain assuming the attic was hot enough. If the fan is pulling in water it would have to be through the soffit vents, which I suppose is possible. This would be consistent with the location of the water damage.
I also had the gutter guards taken off this morning. They are the plastic variety and over the years, had begun to "cup" which in some locations could have left standing water against the shingles. The top part of the guards is fairly long and extends well into the first row of shingles, and with the steep pitch (8/12) of the roof, I'm not sure if water could get all the way up to the sheathing. I'll have to put a few back on and get out the hose for a little experiment.
These are the two leading theories. Is there an easy way to test the first one?
Hey 86
probably not ice damming since you dont get much ice in Atlanta. (assuming you are in atlanta, ga and not atlanta, Idaho or Atlanta, Mo)
I am guessing, since it is a high humidity environment, that you have air flow issues.
Are there soffit vents in the soffits?
Are they continuous?
The poor insulation (the insulation should be 12" thick at the end or there should be a baffle and batts stuffed in there to provide the most insul) might cause the cool air to push thru and cool the roof to the point that you are getting condensation there if there is minimal air flow. I think that is a bit of a stretch of a guess but Ir recon that in theory it is possible.
what do you have in the way of ventilation?
What is age? Do you know how roof was installed?
Picts of exterior might be good too.
I am guessing that it is probably leak but you need to give more info.
Sounds to me like your problem is most likely a combination of improperly installed gutter gaurds and a lack of drip edge.