How do you locate roof leaks?

Question

Sometimes the source of a roof leaks is difficult to find.

The best approach that I've found for locating the leak is to have someone watch where the water is coming into the house (may be easiest if this can be done in an attic) and have a second person spray the roof with a hose. Spray first at lower elevations and keep spraying the same spot for at least a minute to give the water a chance to make it inside. If the water doesn't show up inside then work your way along the roof at the same elevation. Then work your way from the bottom to the top until water starts coming in. The source of the leak is likely close to the spot you're spraying or where you sprayed last.

What techniques have you found useful?

Answer 1

I had a leak caused in a sun-room that was hard to identify. It turns out the roof to wall flashing wasn't properly secured under the siding. It only ever leaked when there was enough water weight to push the flashing down causing it to pop out from behind the siding.

Long story short, ensuring that the flashing is properly secured is one of the first things I check.

Answer 2

Old question, but we had a leaking roof that would only cause a problem when we had very heavy rain and strong southerly wind. Our builder had to cut a hole in our ceiling (it was already water damaged and had to be replaced) and stick his head in the roof during such a storm (Saturday night of course). Even after that, he could not find a leak. The fix was eventually to lay down more and more lead flashing until the leak went away.

Then it came back, so they siliconed up the titles to the edge of the roof. That seems to fix the leak.

Then another part of the roof started leaking.... yet to find that one.