Roof "hog valley" leak problem

[jj3000]

My home has a valley where a roof joint another roof and it is a V shape, I believe it is called a hog valley.

From the center of the valley there are no roof tiles for about 1 foot in both directions.

The problem is that this area holds standing water and I'm having trouble with some water leaking into the attic and studs in one particular spot. I had a roofer came and he had coated it with what looks like some tar and then a silver aluminum colored paint/coating.

It's been raining and that spot is wet again. I think the roof guy will warranty his work but I might have to find a way to fix it myself because I'm in CA and it doesn't rain very often. My roof is about 8 years old and it's got a layer of old roof below it already. It could be leaking down from some other spot but I would think it's likely the valley..

Any advice is appreciated.

[John B]

Yes. You have a tough one. That's because you have two layers. But your "outer" roof is still young. The leak is higher than your roofer suspected; I know that because he didn't fix the problem. Maybe you didn't tell him that you have two roofs. The wet spot you see is a consequence of the OLD leak in the UNDERLYING roof. IOW, the new roof is leaking at a higher eleveation, and the water runs between the layers, only to percolate through the aforementioned old leak. Why do roofs leak? Sometimes because heavy feet damage the membrane. So suspect the pathway commonly, and casually, used on the roof. But on a roof so new as yours, look for outright tears and cracks. And don't forget to inspect flashing and the caulk that may be required. Is there a chimney in the mix, here? If you want to fix a leak, you must "think like water." And look beyond "hog valley." The water is running to the valley, after entering in a place you least suspect.

"jj3000" wrote

[John B]

Well, if you're gonna troubleshoot a leak, and you have enough patience, then you apply water to the lowest suspected elevation, and check for leaks. You progress higher and higher, until you score. Of course, you might have leaks in two places, etc. "Goedjn" wrote

You gotta be kiddn'

Fix the damn leak!

[Goedjn]

Wait until everything dries, and ppour a bucket of water into the valley. If it ends up inside, then that's where the leak is.

Drill a 4" hole in the lowest part of that valley, and install an internal drainpipe. This is why only people with more "artistic" sense than common sense build roofs that way.

[Roger T.]

A flat or hog valley is usually avoided by builders, as they are nearly impossible to waterproof due to lack of proper slope. Here is a link to what you may have on your house;

One of the posters above suspect the leak may be above the valley, but whenever I have had leakage, I found a flat valley to be the cause, even though the area looked well sealed. As others have suggested, pour from a bucket or better yet or run water from an open (no nozzle) hose, to see if leak is really where you suspect. If it doesnt leak, dam up the valley so it backs up a little, simulating heavy rain. If the leak is there, then I would be seriously tempted to re-pitch the valley, or rebuild the decking in that area so there is rapid drainage. I know this isn't what you want to hear, but valley leaks, if you have one, are damn hard to cure with sealant, tar or other roof repair goop.

[jj3000]

Thanks for the advice, I'm going to fill the valley up when it's dry to make sure it is NOT the valley's fault first.

However we are going to have rain this whole week.. how can I minimize the amount of water getting into the house? Perhaps a big tarp?

[John B]

[John B]

Yeah, you can do that. But you have to tarp from the bottom to the top; the entire watershed. Layer it, and fasten it somehow to preclude wind damage. If your house has no parapet with drain holes (like a commercial building) then there is less threat of catastrophic roof collapse, in the event that a tarp manages to obstruct drainage holes. I have not seen a picture of your roof, so you'll have to evaluate any such threat yourself. Painter's tarp, as comes in a big roll, either 9' or 12' wide, is one way to go. Sunlight will disintegrate the plastic if you leave it up there for three months or so. "jj3000" wrote

[jj3000]

Hi John B,

The roofer came back to check out the situation, I shown him the valley coating did not fix that previous leak.

He looked and measured for a while, and found that the flashing isn't dropping down to the scrupper, he explained to me there were 2 flashings for the valley. The top flashing seem to be leaking down to the bottom flashing at the edge, the bottom flashing is about 10 ft long each and soldered in the middle (and eventually leaks), which is about where it is leaking inside the house.

He hammered the lip down and applied some flashing cement with a layer of fiberglass tape and that should make sure the water doesn't leak into the bottom flashing. I hope that will fix the problem..

[John B]

Jeremy, It's amazing how much water can come through a tiny defect, in a hard rainstorm. Good luck. There are some great tapes out there. John