In this video, This Old House general contractor Tom Silva installs a new skylight into an existing opening.
How to Replace a Leaking Skylight
- Use a flat pry bar to remove roof shingles, starting three or courses above the skylight.
- Then pry up roof shingles from each side of the skylight, revealing the step flashing.
- Unscrew and remove the counter flashing from around the skylight.
- Pry off the step flashing from the sides of the skylight.
- Unscrew and pry off the head flashing from the top end of the skylight.
- Use a utility knife to slice through the ice-and-water membrane around the skylight curb.
- Peel back the membrane to expose the metal brackets holding the skylight to the roof deck.
- Unscrew the brackets from the skylight curb, then pull the skylight from the opening.
- Slice through the membrane along the bottom to free the skylight from the roof.
- Before installing the new skylight, mount the solar-powered window shade and the interior wooden trim package.
- Nail vinyl strips around the perimeter of the roof opening to cover the exposed edges of the drywall.
- Set the new skylight into place, centered in the roof opening.
- Secure the skylight by driving 2-inch galvanized ring-shank nails through the mounting brackets and into the roof deck.
- Apply self-sealing ice-and-water membrane along the bottom of the skylight.
- Lift the rubber gasket attached to the lower end of the skylight, and slip into place the bottom flashing.
- Nail the bottom flashing to the sides of the skylight curb and down to the roof deck.
- Cover both sides of the skylight and bottom flashing with continuous strips of self-sealing membrane.
- Reinstall the roof shingles removed earlier, starting at the bottom and working up the roof.
- Along the sides of the skylight, install a piece of step flashing in between each course of shingles. Nail the step flashing to the skylight curb, not to the roof deck.
- Continue to install roof shingles, making sure you don't nail through the step flashing.
- Install counter flashing around the perimeter of the skylight, starting at the bottom.
- Then attach counter flashing along each end and finally across the top of the skylight.
- With the counter flashing installed, screw the head flashing into place. Be sure the upper edge of the flashing is tucked beneath the roof shingles.
- Install the remaining shingles above the skylight.
- From below test the operation of the solar-powered window shade.