How to Diagnose and Track Down a Roof Leak

Culprits May be Chimneys, Flashing, or Asphalt Composition Shingles

Aug 25, 2009

Finding a reason for a leaking roof isn't always easy. In easy cases, a homeowner can find it and repair the shingles. A roof contractor can save time on hard cases.

The ways in which rainwater gets past asphalt composition shingles and roofing felt before making it through the ceiling are many. In some cases it's just an old roof and is worn out. In this case it doesn't make good financial sense to do major repairs, although a patch job with roofing cement will sometimes stretch it until the federal income tax return money arrives.

Then it will be time to hire a competent roofing contractor to re-roof the home with high quality shingles, or even a metal roof if that's in the budget and allowed by the neighborhood homeowners association.

Attics with Radiant Barrier Foil are a Special Case

Withenergy costs escalating so rapidly, many homeowners are opting to install radiant barrier foil in their attics. When stapling it to the rafters or trusses is the installation method, the leak will likely become apparent on the bottom of the fascia boards, perhaps dripping out from the soffit vents.

Determining where the water has made its way through the attic insulation and drywall ceiling is a logical first step. Although this location won't pinpoint the spot on the roof up above, it can narrow it down to a quadrant of the house or so.

Next, go into the attic and examine the spot from above. With any luck, there will be evidence on the roof sheathing directly above. Otherwise, check for water stains on rafters or trusses where the water may have run down with gravity before dripping down onto the attic insulation.

Examine the Roof from Above

Be sure to follow all ladder safety rules when going on top of the house. Examine the suspect area. Look for things like dislodged flashing at the chimney and plumbing vent stacks. These are easy to seal with roof cement.

Look at the mounting bracket for any TV satellite antenna in the area. Antenna installation techs are not always well-versed in making waterproof installations.

Do all the shingles lay flat? Popped nails can let enough water in during a heavy rain to cause damage.

Finding Leaks on Newer Roofs

If the home itself or the re-roofing job is less than about 3 years old, it's a good bet that the problem is not due to the age of the materials. One possible problem is where the roofing contractor used shingles with continuous seal-down strips. These strips are those mastic strips on the back side of the shingle Some manufacturers will make shingles this way; Easier production is one explanation.

The strip should be discontinuous, like the stripes down the center of a highway. This allows any rain that gets blown under the side of the shingle during high winds to exit the bottom and escape down the roof's slope, following gravity. Without this gap, water travels horizontally until it finds the seam between adjacent shingles.

At this point the water is on the felt and is free to move until it finds a way into the home, usually a perforation where a nail head doesn't make a good seal.

The bottom line is to use quality building materials and a reputable roofing contractor.

The copyright of the article How to Diagnose and Track Down a Roof Leak in Home Renovation/Repair is owned by Kelly Smith. Permission to republish How to Diagnose and Track Down a Roof Leak in print or online must be granted by the author in writing.