How to Repair & Caulk a Roof Dormer

Find the exact point on the dormer that's leaking. Use a flashlight to inspect the attic floor for a puddle of water when it rains, and locate the leak from inside. Inspect the caulking for holes, missing sections or cracks around the dormer window. Water seeps its way through the damaged caulk, behind the flashing and into the house. Check the shingles on top of the dormer for damaged, loose or missing sections that may be causing the leak.

Set a sturdy ladder against the exterior wall and climb it to access the roof. Inspect the edges of the dormer for peeling or cracking. Also inspect the flashing to determine whether it has rusted or come undone.

Position the tip of a putty knife on the caulk around a corner of the dormer. Tap the putty knife gently with a hammer so it loosens the caulk and makes a hole. Insert a pry bar in the hole and pry the dormer up to loosen and release the caulk surrounding it. Continue this process until you remove the caulking around the dormer.

Inspect the shingles around the area to determine if they can be lifted without breakage. Keep a few shingles at hand in case you need to replace any. Carefully lift and fold the shingles until you remove the caulking.

Grasp the old flashing and carefully pull it away from the dormer and shingles. Clean the exposed surface with a brush to remove accumulated dirt or debris, or use a stiff scraper to remove rust deposits.

Measure the flashing and cut a new sheet of metal flashing to size using tin snips. Push the new flashing to fit directly under the folded shingles and around the dormer. Pound nails into parts of the flashing that don't fit under the shingles, and cover the exposed nail heads with roof putty or caulk.

Replace the shingles back over the flashing, ensuring they're flat. Apply a bead of silicone latex caulk around the edge of the dormer and each shingle. Press the caulking with your finger to make it smooth all the way around and to remove air pockets or bubbles.