Quick Answer
Skylight leaking is most often caused by damaged or improperly installed flashing, clogged drainage or weep holes, worn seals, or condensation that drips and looks like a leak. The fastest fix is to determine whether the water appears only during rain (roof or flashing issue) or during cold and humid conditions (condensation), then address the true source.
Why This Happens
A skylight is a roof penetration, and roof penetrations rely on properly layered flashing to keep water moving away from the opening. The National Roofing Contractors Association explains that flashing is what prevents water entry at roof penetrations like skylights.
NRCA Roof Builders Handbook – Flashing and Roof Penetrations
Not all skylight leaks are structural. Moisture can also come from condensation forming on cold glass and dripping down, especially in humid rooms. This is commonly mistaken for a roof leak.
Family Handyman – Skylight Leaks vs Condensation
What NOT to Do
Avoid these mistakes that often make skylight leaks worse:
- Do not smear roofing cement or caulk over everything
- Do not ignore small drips or stains
- Do not assume the skylight is always the problem
- Do not climb steep roofs without proper safety equipment
- Do not paint over water stains before fixing the moisture source
Step-by-Step Fix
- Determine if the leak only appears during rain or also during dry, cold weather.
- Inspect the skylight glass for moisture buildup that suggests condensation.
- Clear leaves and debris from around the skylight exterior.
- Check for clogged weep holes or drainage channels.
- Improve indoor ventilation if humidity is high.
- Dry all affected areas immediately to limit damage.
The EPA recommends drying water-damaged materials within 24–48 hours to help prevent mold growth.
EPA – A Brief Guide to Mold, Moisture, and Your Home
Alternative Fixes
If the leak continues after basic checks:
- Have flashing professionally inspected or replaced
- Use manufacturer-approved flashing kits
- Replace older skylights with failed seals
Family Handyman – Making a Skylight Leakproof
Prevention Tips
Reduce the risk of future skylight leaks by:
- Keeping the skylight and roof area clear of debris
- Controlling indoor humidity
- Running bathroom and kitchen exhaust fans
- Inspecting the roof after major storms
FAQs
- How can I tell if it’s condensation? Condensation usually appears on the glass and can happen without rain.
- What is the most common structural cause? Improper or failing flashing.
- Can clogged weep holes cause leaks? Yes, water can back up and spill inside.
- How fast should wet areas be dried? Within 24–48 hours.
- When should I call a professional? If leaks persist or roof access is unsafe.
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