Spotting evidence of a roof leak is never pleasant. When you see water stains on the ceiling or running down a wall, it can be difficult to pinpoint the problem area. But if staining occurs after heavy rain, ice, or other inclement weather, there’s likely a roof leak that can lead to mold, damaged ceilings, destroyed insulation, and rotted framing.

How to Find A Roof Leak

There are several types of roof leaks, but a homeowner’s first mission is to find the leak, then repair it to mitigate the damage. The leak may be several feet to the side from an interior water stain. You should therefore visibly inspect the roof, starting uphill of the stains. Check for penetrations in the roof, including plumbing and roof vents, chimneys, etc.

Start your leak detection strategy by looking for attic condensation. However, you may need to get onto the roof if you have a vaulted ceiling. If you can’t find the source, spray a garden hose above the suspected area. Start uphill of, for example, the chimney, and have someone inside check for dripping water. If this doesn’t help, remove shingles to look for water staining, rotted wood, or discolored felt paper.

Most Common Areas for a Roof Leak

• Shingles: Leaks may come from cracks or where a nail has lifted out of the roof sheathing. The roof field itself can have many leak points, including the slate. Check the vertical knockouts of each shingle for damage. It’s easier to walk around a roof if it’s made of asphalt, while other materials such as concrete or clay tile can be more difficult.

• The Valley: Located where two roof planes intersect, valleys can be problematic leak points if your shingles aren’t properly trimmed. Cutting a shingle results in a chisel point, which requires a second cut to make it point like an arrow. Otherwise, water will flow from the top of the shingle into your house.

• Flashings: Roofs that stop at a vertical wall have head wall flashings to direct water away from where shingles end. Step flashings used if the roof climbs alongside a vertical wall can develop rust or holes. Other problem areas can be plumbing vent flashings with cracked rubber around the pipe. Similarly, furnace or B-vent flashings can be leak sources, especially if a metal storm collar (used around vertical piping extending through the roof) is loose.

• Chimneys: There are four types of flashing used for chimneys, as well as counterflashing for the brick mortar joint. Just a hairline crack above the flashing can trigger a leak. Soldered flashing corners can break or develop holes. Caulking is not an effective repair for this type of problem.

• Ice Dams: When ice forms on the roof, it blocks any water from flowing down naturally. When the water backs up, it can seep under shingles, flashings, and tar paper. The dripping can continue for days and cause slow, but significant, damage.

Roof leaks can occur even if your roof is in good shape. Wind can blow rain under roofing materials from across the surface. Missing siding above the roof can cause a leak as well, while some leaks don’t come from the roof at all. They can come from attic condensation or cracked chimney crowns.

If you suspect a leak and don’t know where it’s coming from, contact Window World of Boston’s roofing contractors, who can thoroughly inspect your roof, install waterproofing, and even provide you with a Total Protection Roofing System®. Request a free estimate or call our Shrewsbury, Pembroke, or Woburn office for more information.