How to Trim a Skylight Opening

If your skylight already has flashing installed, pry it off carefully using a pry bar or putty knife. Be careful not to damage the skylight or the surrounding area.

Step 2: Apply a sealant

Apply a bead of sealant to the inside perimeter of the skylight opening. This sealant will help prevent water from leaking into the skylight well and causing damage.

Step 3: Fasten the Z-flashing

Cut the Z-flashing to size and fasten it to the skylight opening using screws. Make sure the Z-flashing overlaps both the roof shingles and the sealant.

Step 4: Install a drip cap

Install a drip cap over the top of the Z-flashing. The drip cap will help direct water away from the skylight and prevent it from pooling.

Step 5: Seal around the drip cap

Apply a bead of sealant around the perimeter of the drip cap. This sealant will help prevent water from leaking into the skylight well.

Step 6: Install trim or siding (optional)

If desired, you can install trim or siding around the skylight opening to give it a finished look.