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How to Locate and Fix a Roof Leak

  • Transcript

    LESLIE: Charles in Pennsylvania is dealing with a mysterious leak. Tell us about it.

    CHARLES: Well, I have a – it’s the section of the house that – in front of the one wall is the garage and behind it is the wall to the house. It’s a family room. And one side, going towards the garage, was having seeping water coming in. I thought it was the roof but I had the roofer who just put the roof on about 18 months ago come check it. He can’t find anything wrong with it. It stopped; it hasn’t done it for a while.

    But I noticed that as I went into the garage the other day, I saw that some of the drywall has started to turn black so, obviously, the inside of the drywall, there’s mold. And I’m trying to figure out where it’s coming from: number one, so I can fix it and number two, of course I’ve got to fix the issue with the mold. Any ideas about where that might be coming from? It’s over the garage for the – the garage roof.

    TOM: And is it near where the garage roof intersects with anything else? Is it intersecting with the house?

    CHARLES: Well, it – the garage roof covers this whole section that – I’m actually sitting in that room right now. And then it goes out and connects with a sun-porch area in the back. But it wasn’t coming from that side; it was coming from the inside wall, which seemed weird.

    TOM: Well, here’s the thing: you may be getting a leak that’s caused just by rain that blows in with some wind pressure behind it: sort of a directional leak. A roofer looking at this and of course, you’re asking him to figure out what’s wrong with your roof and of course, he knows darn well that he put the roof on and he’s not going to be willing to admit very readily that there’s anything wrong. But the truth is you may have a leak that’s caused by driving rain and that’s why it may not happen all the time.

    It’s pretty common, actually. It usually happens at an intersection point, not in the middle of the shingle. Usually at a point where it intersects with something else.

    LESLIE: When you’ve got wind-driven rain and your wind is lifting up a shingle and the rain is, you know, falling horizontally because of the wind and getting up and under.

    CHARLES: Yeah. We had never had this problem – like I said, the roof is new and – it’s relatively new. About 18 months old. And until about 3 months ago, about 15 months of it, there had never been even a sniff of a leak.

    TOM: Well, roofs are always expanding and contracting and they can develop these types of leaks. One way to try to diagnose it, if you don’t see anything that’s visually wrong, is to go up there with a hose and start low and run the water down the roof, again, towards the low side and then bring it up higher.

    CHARLES: The hose?

    TOM: And see if you can actually physically make it leak.

    CHARLES: Yeah, yeah. I see what …

    TOM: And that will kind of show you the general area.

    But if you find it, then what you have to do is take the shingles apart there and reroof that particular spot.

    CHARLES: Yeah.

    TOM: Now, in terms of the area of the wall where you’re seeing these black stains, that may or may not be mold. I mean when drywall gets wet, it does tend to turn dark and it may not be dark with mold. But what I would do is I would prime it with an oil-based primer. And so I would prime the surface and then put a top coat of paint on it. If you just paint it, the stain will come back through; you must prime it first.

    CHARLES: Well, I’ll give that a shot. I’ll give that a shot. Alright. I thank you very much.

    TOM: Good luck. Thanks so much for calling us at 888-MONEY-PIT.

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