How to seal and repair roof leaks

If rain drops keep falling on your head when you’re standing in the kitchen, it’s time for some repair work. Once you’ve located the source of the leaks, here’s how to seal those roof leaks.

What You'll Need

  • 1

    Gather tools

    You’ll need:
    • Through the ROOF!
    • Utility knife for removing old caulk, opening the caulking tube, and cutting shingles to the right shape
    • McKanica® Silicone Caulk Remover or similar product if silicone is present
    • Matching shingles
    • Caulk gun (for cartridges) or foam brushes (for brush-on grade)
    • Trowels or foam brushes for tooling
    • Mineral spirits for clean up
    • Proper safety equipment to access the roof top
    • A spy glass to take a quick look around the neighborhood, since you’ll be on the roof anyway

  • 2

    Find the leak

    If it’s not obvious (like your skylight is dripping on you), you’ll have to dig a bit deeper. If you have attic access, the easiest way to track down a leak is to go up there with a flashlight and look for the evidence: water stains, black marks, mold, etc. If attic access is a problem or you have a vaulted ceiling, time for a trip to the rooftop. (Be careful!) Start by checking all roof penetrations (vents, boots, flashing, etc.) Still can’t find it? Time to contact a pro.

  • 3

    Clean the surfaces

    Through the Roof! Roof ApplicationIf you want your caulking job to stick and stretch for years to come, make sure you clean the surfaces. Remove old caulk, loose asphalt, loose shingles, and clean the surface of any dust, oil, pollen etc. If silicone is present, use a silicone caulk remover.

  • 4

    Apply the caulk.

    Apply the bead at least 1/8” to 1/4” wide to ensure there’s enough there to both stick to the joint and stretch with movement. If applying the brush-on grade, apply between 1/8” to 1/4″ thick.

  • 5

    Smooth (tool) the bead

    IMG_0178 Use your finger, a beading tool or foam brushes, along with soapy water or mineral spirits, to smooth the bead. This provides best adhesion and greater longevity. (Skip this step for brush-on grade.)

  • 6

    Clean up

    Use mineral spirits to clean up tools and surfaces.
    Now, test it. Find a friend who is a risk taker, then take a hose to the roof to see if your newly-sealed roof is truly leak-free. (We’re pretty sure you’ll still be friends because this stuff actually works.)

 Special Tip

Use Through the Roof! to seal penetrations from the attic side to help prevent ice dams in winter. We can’t promise the kids won’t be a bit disappointed by fewer icicles. If they do complain, direct them to this post on how to seal roof leaks and maybe they will understand.