Should a skylight be repaired or replaced?
Short answer. Repair a skylight when the unit itself is sound and the problem is flashing, a gasket, an exterior seal or debris, and replace it when the glass is fogged between panes, the dome is cracked or yellowed, the frame is rotted, or the unit is around 20 years old. If the roof is being replaced anyway, replacing an older skylight at the same time is usually the better value.
Usually repairable
- Leaks at the flashing while the unit is in good shape: reflash it.
- Dried exterior gaskets or seals on a curb-mounted unit: replace the gaskets or reseal.
- A debris dam on the uphill side: clean it out and check the flashing beneath.
- Condensation: improve ventilation and run exhaust fans; the unit is not failing.
- A broken operator, motor or screen on a venting unit: replace the part.
Usually a replacement
- Fog between the glass panes, which means the insulated seal has failed and will not clear.
- A cracked, crazed or yellowed acrylic dome, including hail cracks.
- A rotted wood frame or curb.
- Leaks that return after a proper reflash.
- Old single-pane units that pour heat into the room every summer.
Replacement options
- A same-size unit with a new flashing kit, the simplest swap.
- Converting an old curb unit to a deck-mounted one, which may need some reframing.
- Replacing a large skylight with a tubular unit and patching the roof and ceiling.
- Removing it entirely and roofing over the opening if you no longer want it.
Timing
Skylight flashing is woven into the shingles, so the most economical moment to replace a skylight is during a reroof, when the shingles are off anyway. See skylights and roof replacement and roof flashing explained.