If your roof is now leaking water into your cottage, here’s what to do.
Finding the leak
Roof leaks are vexing. Most hide during fine weather, only springing to life during bouts of precipitation, and, because of this, they can sometimes take weeks to discover. Montreal-based roofing consultant Paul Grizenko recommends looking for wet or stained drywall, bubbling paint, pools on floors, wet insulation, and mould. From there, use a flashlight and a thermal imaging camera to trace your leak to the source. It’s often in the attic, says Grizenko. Usual suspects include bad seals or failing caulking on roof penetrations—think vents, plumbing stacks, and chimneys—and cracked or missing shingles atop compromised underlayment. Also common are ice dams (often around roof eaves and valleys), where winter ice buildup causes snowmelt to back up and seep beneath shingles and underlayment.
Stopping the leak
Grizenko recommends roofing cement for small jobs, such as repairing a cracked asphalt shingle. “It’s not pretty, but it works as a temporary patch.” If you’re heading to the roof immediately, Grizenko suggests driving a screw from the attic through the roof deck at the leak area so it’s easier to locate from above. Once on the roof, mark the area and remove the screw.
Next, sweep or brush loose asphalt, dust, and debris from the repair zone. Use a putty knife or a trowel to work layers of the sticky cement into the crack, filling it completely while maintaining a fairly thin cover of roofing cement on top. Trowel the outer edges of the patch flush with the surface. For best results, read directions carefully (cements differ per manufacturer) and choose a mild, dry day. Grizenko says roofing cement is too viscous in the cold and too runny on hot days.
Leaks from faulty seals around flashing (the thin metal sheets on roof seams that direct water away) and roof penetrations will likely require new caulking. “Between ultraviolet exposure and thermal expansion, caulking becomes brittle and pulls away from whatever it’s protecting over time,” says Grizenko. Use a utility knife to cut away the old caulking and clean off the old residue with acetone. When the surface is dry, apply new, high-quality roof caulking, such as Through the Roof! sealant. If the leak stops, you may have solved the problem, but only for the life of the caulking.
If you can’t get to the roof right away—say it’s raining or you’re preparing to leave—tarping can serve as a short-term stopgap and is best left to professional contractors. “It takes experience to know how to secure a tarp that won’t blow off or rip,” says Grizenko.
Fixing the leak
To properly fix a leak stemming from a broken asphalt shingle on an otherwise-healthy roof, use a flat pry bar to gently bend up the shingle(s) covering the one you’re replacing. Next, use the pry bar to remove the nails securing the faulty shingle: again, gently. Pull out the broken shingle and slide the replacement beneath the upper course, nailing it down using the same nail pattern as the rest of the roof. Apply roofing cement beneath the tabs and on the nail heads of the new shingle, then press the shingles into place. Book the job for a mild day, when asphalt is less likely to crack.
If you notice many lifting, missing, or broken shingles, plan a new roof—and consider everything from the sheathing to the water barrier. Also, don’t cheap out: “If the person who is charging more can explain why, and give clear indications of the extra steps they’re taking, they may be the cheapest person to hire in the long run.”
Related Story 3 leaks you can patch (and 2 you can’t)
Related Story How to fix a leaky pipe at the cottage
Related Story Cracked canoe or kayak? Here’s how to fix your leaky boat