By Skylight Experts
What is flashing?
Flashing is the sheet metal or waterproof membrane that seals the joint between the skylight and the roof. It directs water away from the opening and prevents leaks. Even high‑quality skylights will fail if flashing is poorly installed. Modern flashing systems include step flashing for tile roofs, apron flashing at the downhill side and saddle flashing at the top.
Why high‑quality flashing matters
The Department of Energy cautions that skylights can create unwanted heat gain in summer and heat loss in winter if not properly sealed. Sunsquare’s guide notes that professional installation is “non‑negotiable” because poor flashing undermines thermal performance and leads to leaks. Thermally broken frames and insulated glazing only achieve low U‑values when correctly integrated into the roof.
Tips for effective waterproofing
· Use manufacturer‑supplied flashing kits to ensure compatibility with the skylight model and roof type.
· Maintain adequate slope – domed or pyramidal glazing sheds water and prevents pooling.
· Inspect seals and membranes regularly and re‑seal where necessary.
· Consider exterior shades to control solar heat gain.
FAQs
Q: Can I install flashing myself?
A: Specialist knowledge is required to integrate flashing with roofing materials. DIY flashing often fails within a few years.
Q: Does flashing differ for metal, tile and membrane roofs?
A: Yes. Tile roofs require stepped flashing, while membrane roofs use continuous membranes.
Q: How long does flashing last?
A: With quality materials and proper installation, flashing can last as long as the roof, though inspections should be scheduled annually.
