What to look for and how to fix leak


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Old 07-02-07, 08:57 AM
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What to look for and how to fix leak

I've never done anything with a roof, so was hoping for some pointers on what to look for, other than walking around with tar and glopping it everywhere suspicious. The roof is about 15 years old now, shingles, and our home inspector said it looked like we should expect at least another 10 years out of it.

The roof has a bit of a leak, but only during serious storms and never right away. I've never gone into the attic at the right time to catch moisture and the rafters are already water stained from before the roof was last replaced (presumably). I eventually notice a small amount of moisture on the dining room ceiling in the corner under the eaves. The problem is this is under an edge, and there is a fireplace, so it seems like it can be flowing from just about anywhere up to the peak. Is there something I can look for? Since it only happens in thunderstorms, can there be wind lifting the edge shingles or something like that? What can I do about that? If I see cracked sealant around the chimney (haven't gone up there yet), is that a likely culprit? Is it reasonable and useful to just run more sealant everywhere there currently is sealant? Is there something I should look for at the ridge vent?
 
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Old 07-02-07, 09:08 AM
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Correction: two edges

To clarify, this leak is under TWO roof edges ...

The roof above the dining room is a little higher, so has an "outer" corner. There is a vertical wall, maybe 2', covered with vinyl siding, then the lower garage roof, with an "inner" corner. About halfway up the slope, there is a chimney between. The attic is all one, just two different roof levels, but I haven't seen moisture anywhere except the dining room ceiling.

For this "inner" corner, I guess I have to look for flashing or cracked sealant? What about the vertical wall: likely things to look for? or fixes?
 
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Old 07-02-07, 11:45 AM
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Rather than running more sealant on top of your existing cracked sealant, it's often best to chip the old sealant off with a hammer and chisel (a stiff putty knife or glaziers knife). Yes, the chimney sounds like a good place to start looking. If it's brick, it could be the cap or the area where the flue comes out. It could also be the step flashings in the brick- sometimes thunderstorms (wind) will blow water back into the counterflashing that is tuck pointed into the brick. If you have brick you can also look for cracks in the mortar. These are best fixed with new mortar, not with caulk. But it depends how extensive the cracking is I suppose.

As far as the wall-roof connection is concerned, it's hard to say, but the biggest problems I've seen are contractors who use continuous flashings instead of individual step flashings (continuous flashings allow water under the shingles, sometimes water migrates off the flashing before it terminates) and bad flashing techniques on the outside corners of walls. Sometimes these problems are increased if a lot of water is getting behind the vinyl siding. You'd really have to remove all the vinyl siding to see if everything behind it is flashed properly, and I really hate to recommend you do that if you are just investigating.

Like you suggested, getting into the attic when it's raining is really the easiest way to start diagnosing the problem, but I know that's hard to do. At least that gives you an idea of where to start looking, realizing that water runs downhill at least you would know where to start tracking.
 
 

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