How to Seal Skylights
- 1). Lift the roof shingles from around the perimeter of the skylight to expose the skylight's flashing.
- 2). Place a layer of roofing cement where the edge of the flashing meets the roof. Use a medium-size putty knife to apply a 1/4-inch-thick layer of roofing cement around the entire skylight.
- 3). Using the putty knife, layer more roofing cement on the underside of the roof shingles that you lifted in Step 1. Press the shingles back into place.
- 4). Seal the edge of the shingles where they intersect the flashing of the skylight, applying the roofing cement with the putty knife.
- 5). Apply more roofing cement to the tops of these shingles along their edges where they intersect with adjoining shingles, completely sealing their edges with the roofing cement. Completely encircle the skylight, sealing the edges of the course of shingles next to the skylight. Pay particular attention to the shingles that are higher up on the roof than the skylight, but don't shortchange the shingles lower down on the roof, either.
