Skylight repair and replacement for Phoenix roofs

A skylight faces the sky almost flat, so it takes the full force of Valley sun for most of the day, most of the year. Acrylic domes, the most common type on homes built from the 1970s through the 2000s, slowly break down under that UV. The surface crazes, clouds over and loses impact strength. Roof surfaces reaching 150 F to 170 F in July also expand and shrink the frame every day, which gradually works the seals loose.

Heat gain is the other side of it. A clear single-pane dome can pour a surprising amount of heat into a room, and plenty of homeowners end up covering theirs with a towel or tinted film. Current skylight glass, with a low-E coating and an insulated unit, cuts that heat sharply while still bringing in daylight. Tubular daylighting devices, often called sun tunnels, are another option where a small, cool light source is all a hallway, closet or bathroom needs.

When a skylight leaks, the dome usually takes the blame, but most of the time water is getting in at the flashing. On tile roofs, the skylight curb sits in a field of tiles, and the flashing has to carry water around the curb and back onto the underlayment. If the underlayment around the curb has dried out, or tiles were cut short when the skylight went in, water finds the gap. We lift the surrounding tiles, check the underlayment and replace the flashing kit before resetting the tile.

On foam and other low-slope roofs, skylights sit on raised curbs that need to be wrapped and coated as part of the roof system, and cracks in the coating at the curb corners are a common failure. On shingle roofs, step flashing and a head flashing do the job. In every case, we'd rather fix the flashing properly than smear more sealant around the frame, because sealant alone rarely survives more than a couple of Phoenix summers. If water has traveled well beyond the skylight, our leak tracing and repair work finds where it's going.

If the frame and curb are sound and only the dome is crazed, a replacement dome can sometimes be fitted to the existing frame, which is the least invasive fix. If the skylight is 20 years old or more, the seals are failing and the flashing is tired, a full replacement with a new curb-mounted unit and flashing kit usually costs less over time than patching it again and again. A fogged insulated glass unit is always a replacement.

Some homeowners decide they want less skylight. A large dome over a family room can be swapped for a smaller unit, or closed in completely and roofed over to match the surrounding tile or shingles. Others trade an old dome for a sun tunnel, which brings daylight through a reflective tube with far less heat. If a new roof or a tile underlayment job is coming up, that's the best time to deal with skylights, since the roof around them is already open.