Should You Replace Skylights When You Re-Roof?
Decide before the old roof comes off. California's code has the flashings rebuilt on a re-roof (R908.6), so every skylight gets new flashing either way; the question is whether the unit goes back in. Replace it if water comes through the unit itself, if the glazing is cracked or a plastic dome has yellowed, or if a film has formed between the panes, which VELUX's warranty attributes to a failed hermetic seal. A replacement has to be tested and labeled to the North American fenestration standard (CRC 2025, R324.6.9) and, on a roof flatter than 3:12, sit on a curb at least 4 inches high unless the maker's instructions say otherwise (R324.6.8). Under the 2025 California Energy Code, in effect since January 1, 2026, a replaced skylight needs a U-factor of 0.40 or less and a solar heat gain coefficient of 0.30 or less (Section 150.2(b)1B, Exception 2). In a wildfire zone, the glazing also needs at least one tempered pane or another listed option (CWUIC 504.8).
Keep or replace: what to look at
Look at each unit from inside and from the roof before the quote is final.
| What you see | What it points to | For the re-roof |
|---|---|---|
| Stains on the ceiling or well around the skylight | The flashing, or the unit's own seals and frame | The flashing is rebuilt anyway; check the unit before it goes back |
| Water on the inside of the glass on cool mornings | Condensation from indoor humidity, which VELUX's warranty says isn't a leak | Not a reason to replace the unit by itself |
| A film or haze between the panes | A failed hermetic seal in the insulating glass, per VELUX's warranty | Replace the unit or its glazing |
| Cracked glass, or a crazed or yellowed plastic dome | Damaged or aged glazing | Replace |
| A unit you'd rather not reopen the new roof for later | Age and remaining warranty | Replacing now avoids cutting into new roofing later |
Glass replaced in an existing sash and frame, or sashes replaced in an existing frame, count as repairs under the energy code if the replacement performs at least as well as the original (Section 150.2(b)1B).
What a replacement skylight has to meet
- Glazing materials. Laminated glass, fully tempered glass, heat-strengthened glass, wired glass or approved rigid plastics (R324.6.2). Where the inboard pane is tempered, heat-strengthened or wired glass, a broken-glass retention screen goes below it, with exceptions for smaller, lower tempered units and none needed for laminated glass (R324.6.3 to R324.6.5).
- Testing and label. Unit skylights have to be tested by an approved independent laboratory and labeled with the maker, the performance grade and the inspection agency under AAMA/WDMA/CSA 101/I.S.2/A440 (R324.6.9).
- A curb on low slopes. On a roof flatter than 3:12, a unit skylight sits on a curb at least 4 inches above the roof unless the maker's instructions specify otherwise (R324.6.8).
- Energy performance. A U-factor of 0.40 or less and a solar heat gain coefficient of 0.30 or less for a replaced skylight; the 2022 code allowed a U-factor up to 0.55. Adding new skylight area brings in other rules (Section 150.2(b)1A).
- Fire zones. Multilayered glazing with at least one tempered pane, glass block, glazing with a 20-minute fire-protection rating, or glazing meeting the State Fire Marshal's standard 12-7A-2, and operable skylights get a noncombustible mesh screen (CWUIC 504.8, 504.8.2); more in WUI roofing requirements in California.
- No cricket needed. A unit skylight installed to the code and flashed to the maker's instructions doesn't need a cricket on its uphill side (R903.2.2); the rest of the roof's flashing rules are in roof flashing types.
Flashing and the leak warranty
Skylight flashing is part of the roof, and it's the maker's kit for that unit and roof covering that the warranty counts on. VELUX, for example, warrants for 10 years that its current deck- and curb-mounted skylights (the A21 series) and their flashing won't leak, provided it's the original installation on a house with one layer of properly installed roofing, installed strictly to VELUX's skylight and flashing instructions. Read the leak terms for the product you're buying, and since that coverage is tied to the original installation, ask the maker how it treats a unit taken out and put back under a new roof.
If solar is coming
An array has to work around skylights, so settle them before the panels go on: on a Long Beach roof in May 2023, the array was split into groups sized to the gaps so the skylight stayed clear (the Long Beach case). How skylights, vents and chimneys shape a solar layout is in chimneys, vents and skylights on a roof.
Frequently asked
Should I replace my skylights when I replace my roof?
Does a replacement skylight need a permit or meet the energy code?
Is condensation on my skylight a leak?
Do skylights need a curb?
What glass does a skylight need in a fire zone?
Related reading
Sources & methodology
Code sections, rules and figures on this page come from the primary sources below. Codes, local requirements and product terms change; each was verified October 9, 2026.
- California Residential Code 2025, Chapter 3 Building Planning, R324.6 Skylights and Sloped Glazing (UpCodes)
- California Residential Code 2025, Chapter 9 Roof Assemblies, R903.2.2 and R908.6 (UpCodes)
- 2025 California Energy Code, Title 24, Part 6, Section 150.2 (ICC)
- California Wildland-Urban Interface Code 2025, Chapter 5, 504.8 and 504.8.2 (UpCodes)
- VELUX America, Limited Warranty (products purchased on or after May 1, 2026)
We check every skylight before the old roof comes off
Call (323) 844-7777. We look at each skylight's frame, glazing and well, tell you which can go back with new flashing and which should be replaced, and put the flashing and any new units into the quote. Have ready the address, a photo of each skylight from inside, and when they were installed if you know.
Prepared by Cali Energy, October 9, 2026. This article is for general educational purposes only and is not legal, tax, financial, engineering, or utility advice. Rates, incentives, codes, permit requirements, equipment specifications, prices, and program terms may change; figures and timelines are estimates, not guarantees. Confirm current requirements with the applicable utility, AHJ, program administrator, manufacturer, or a licensed professional. See our Content Disclaimer. Cali Energy · 19201 Parthenia St, Unit E, Northridge, CA 91324 · CSLB #1032379 (B, C-10, C-39)