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Locating Flat Roof Leaks

Tips on Locating Flat Roof Leaks

Flat roof leak roofs can be a devil to locate. The reason is that water can enter one spot and not really express itself inside until it is far away from the leak. The same thing can happen on sloped roofs, however, you can usually discount all the roof area below the area where you see the leak.

Why? Because water doesn't generally flow uphill from the leak location. Flat roofs allow the leak to travel in any direction from the leak point. That is why they are tough to locate.......

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Start With a Dry Roof

If you have a flat roof that leaks, get up on it when it is dry and cool. You want to look for trouble spots that generally are the primary source of leaks.

I always start at flashings. Flashings are transitional roofing materials. A flashing connects a roofing membrane to something that is not a roof. For example, If a plumbing stack or chimney pops up through the roof, it will be surrounded by a flashing. Often the flashing materials are metal.

Look for cracks. Look to see if the flashing overlaps the roofing material such that downward falling water will be deflected away from the chimney, wall or plumbing pipe.

Check the edge of the roof. Often flashings are used at these points as well. See if they are secure. Look for little cracks, openings, or breaks in seams in these flashings.

Dry Mini Lake Beds

Often water will pond in low spots in a flat roof. You will see evidence of these areas on a flat roof. Look for concentric rings of dirt as the puddles dry out. Look here for tiny holes or splits in the roof.

Seams - A High Priority

Any seam in the roofing material is a natural spot for a leak. Look closely at all seams. Do you see cracks or holes of any type? Is there a place where you can lift a small edge of a seam?

Testing For Leaks

You can test for leaks using a hose. But you have to be patient and you need to work backwards away from gutters or center drains. It can take hours, as you need to let the water run slowly over areas you think are trouble spots. Remember, it can take 10 minutes or more for the water to begin dripping inside. Start near a drain and let the water slowly run.

Periodically, adjust the hose so water flows across dry portions of the roof. You will need tremendous patience, especially if all portions of the roof appear tight.

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Related Articles: Newer Rubber Roofs, Membrane Roofing Types, Membrane Roofing, Manufacturers

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5 Responses to Locating Flat Roof Leaks

  1. Thank you Tim,
    This article was useful. I actually contacted you regarding my flat roof leak, and you asked for photos. I sent you some on the 18th July. Probably you missed my reply. Anyway, we laid new concrete, sealed it, and then put down some tiles, as the people who live above wanted this. I put a decent slope on the roof - about 6 inches for 15 feet. The people upstairs were pretty angry about the slope, but I wanted to stop the leak - so far so good. Anyway just wanted to say thanks and wish you a pleasant Christmas Holiday. Paul

  2. My flat roof is not exactly level as the whole plane of the roof is slightly tipped toward one corner to a roof drain. The roof is concrete with ceramic tile pavers. We have developed a leak. After the drip inside ceased I used the garden hose method starting on one side uphill from the drip leaving the hose run for about 3 days and moving the hose slightly every few hours. Eventually I got a drip !. It may well be where the roof abuts the parapet wall. My question is: Is there a
    detector that will show me where the moisture is below the slab ? I have read that infrared photos would show that and I should take the pics at night when the roof is dry. The moisture below the roof would show up in the pic because it would be warmer than the exposed dry roof.Have you heard of this and do you know of some device that
    would give me this info ? I don't have an infrared camera. Obviously
    I don't want to tear up any more tile than necessary

  3. I have a fall roof that leaks during heavy rain only I have tried to stop it by looking at water drips inside of home but I was unsuccessful can you give me some advice on how to stop the leaks , I don't have the money to replace the roof ps rain coming later tonight please help asap may God bless you

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