How do I trace a most bothersome roof leak?

January 4, 2005 10:26 PM

Roof leaking. Brain hurting. Help.

How do I trace a most bothersome roof leak. We've patched w/tar on some places we though were obvious and now it's just worse. And no, we don't have the money to hire someone. And yes we know we need a new roof. Ideas?
posted by damnitkage to home & garden (9 comments total)

A flight into town on a clear day reveals that many in the vicinity of Seatac International Airport have embraced the tons and tons of blue tarps method of roof repair. It sucks, but it might provide a temporary fix.
posted by stet at 10:41 PM on January 4, 2005

1. Look for wood rot;
2. Or, grab a pair of walkie-talkies; you on the roof with a bucket of water, friend/SO underneath; pour a little bit of water on different areas of the roof until you get a leak underneath, and communicate what you're doing
posted by AlexReynolds at 10:44 PM on January 4, 2005

I googled "finding roof leaks" and came up with this (among other things): "If, after a thorough external inspection, you are unable to locate any obvious sources of the leak, it's time to do an internal examination of your roofing structure. To do this, you should enter your attic on a bright, sunny day. Then turn off any lights and cover any windows in the attic to darken the space. Any light then seen shining through will reveal cracks or holes from which your leak may surely stem. Be sure to also inspect the areas around vent pipes, chimneys and skylights; these are places that have had the roof decking cut and resealed, so they are often culprits for broken seals or flashing. Should all else fail, you may need to flood the suspect area of the roof with your garden hose while someone in the attic watches for the drip to appear."
posted by LarryC at 10:54 PM on January 4, 2005

Assuming it's a flat tar roof. I've seen around ten leaks here in NYC on tar roofs, and they've all been under areas of significant roof sag. It's never been my responsibility to fix it, luckily enough. Google told me that stuff about tar joints around vent pipes and chimneys as well.

Putting some of your left over tar around the edges (the high edge if there's any slope at all) on that blue tarp^ might be the budget fix.

Check your drainage as well. A big puddle means water sitting on areas that wouldn't normally be covered. There's not a lot you can do other than making sure the drain is clear, but I have to scrape leafy muck out of mine a couple times a year.
posted by Jack Karaoke at 11:49 PM on January 4, 2005

I went up on my roof with a pro. he found a crack across the roof I didn't see during my original inspection, about six feet upslope from where the leak appeared in the attic, so do a close inspection with good light. water sometimes travels under the roof a ways before it appears below. good luck.
posted by hortense at 1:25 AM on January 5, 2005

What LarryC said, except I'd add that looking for light only goes so far, since water can turn corners that light can't. Look for dark spots and lines. Attic + Moisture == Mold, and with a leaky roof, you only need follow the mold.
posted by Laen at 2:41 AM on January 5, 2005

I've got a hip-and-valley shingled roof, and recently discovered a single nail that was wicking rainfall through to the attic, so it could be things as (seemingly) trivial as that.
posted by adamrice at 7:09 AM on January 5, 2005

Do you have snow/ice on your roof? If so, you likely have an ice dam.
What happens is the heat from poor insulation and poor roof ventilation melts the snow/ice on the roof. As the meltwater runs down the slope of the roof, it refreezes at the eaves (where there's no heat escape). This forms a dam of ice at the eaves and a standing pool of meltwater just above it. Standing water will leak through nailholes into the house. The best way to (temporarily) fix it is to melt the ice dam with a heater cord (check your hardware store) to allow meltwater to drain away. The best permanent solution is to reshingle and put a heavy membrane along the bottom 6 feet of the roofline.
posted by rocket88 at 8:06 AM on January 5, 2005

Having been married to a roofer once upon a time, I think that the "light in the attic" approach is useless. Water can enter the ceiling well away from the leak, and insulation is going to make it even less likely that you'll see daylight through the roof.

Your course of action really depends on what type of roof you have. Shingle, metal, asphalt, tile, slate? Flat, sloped, or steep?

You could have an ice damming problem, like rocket88 suggested, or your chimney flashing could be the culprit. Unless you are really comfortable with self-diagnosis, I'd get a contractor to look at it.
posted by tizzie at 12:49 PM on January 5, 2005