Most Toronto homeowners think about their skylight twice — the day it's installed, and the day it leaks. Between those events, there are 20+ years of subtle wear, predictable failure points, and small maintenance moves that mean the difference between a 15-year unit and a 25-year one. This guide walks through the full lifecycle so you know what's normal at each stage.
Year 1 — the bedding-in phase
A new skylight settles in during its first year. The flashing develops a weather-tight bond with the surrounding shingles, the sealants cure fully, and any installation issues surface during the first complete weather cycle (one summer of heat, one fall of leaves, one winter of ice-and-thaw).
- Watch for: any ceiling staining around the shaft, any visible gap between flashing and shingle, any condensation inside the glass
- What to do: a casual visual inspection each season. Take a photo on a sunny morning to use as a reference for later
- Common issue: minor condensation in the first winter is normal as the surrounding drywall finishes drying. Persistent condensation past year one means a ventilation issue, not the skylight
If anything looks off in year 1, get it looked at while it's under warranty. Most major-brand units (Velux, Fakro, VKR) carry 10–20 year manufacturer warranties on the glass and frame; installation warranty from a quality installer like Toronto Skylight Installers covers the flashing and labour.
Years 2–5 — the steady state
This is the easy stretch. A correctly installed skylight needs almost no attention from years 2 through 5. The unit performs as designed, the surrounding shingles age in step with the rest of the roof, and the interior shaft holds its finish.
- Maintenance: clean the exterior glass once a year (spring), check the interior shaft for marks from condensation or dust
- Watch for: any unusual draft around the frame on cold days (signals a gasket issue), any change in window operation if vented
- Common upgrade: if you didn't add motorized blinds at install, year 3–5 is when many homeowners regret skipping them, especially on south-facing units
Years 6–12 — first signs of wear
The first decade is when small wear shows up. Gaskets start to compress, sealants begin to dry, and the surrounding shingles start to age more visibly. Most issues at this stage are still in the repair-not-replace category.
- Watch for: hairline cracks in exterior sealant, slight gasket compression (look for daylight at the closed seal), or any minor staining on interior shaft
- What to do: consider a professional inspection at year 10 — about $150–250 for a thorough check. Cheap insurance against a failure cascade
- Common repair: sealant re-bedding around the curb, $300–500, extends life 5+ years
Years 13–18 — repair territory
This is the most active decade for skylight repairs. Flashing details that were marginal at install start to fail, the IGU (insulated glass unit) seal may begin to weaken, and weather-side sealants harden enough to crack. Most issues are still cheaper to repair than replace.
- Common issues: flashing failure ($350–700), gasket replacement ($280–550), minor leak repair ($400–900). See skylight repair Toronto for typical scope
- What to budget: expect to spend $400–1,200 across this five-year window on cumulative repairs
- Decision point: if you've already done two repairs, the third one is a signal to start budgeting for replacement at year 20–25
Years 19–25 — end-of-life planning
By year 20, even quality skylights are nearing end-of-life. The IGU seal is past its design lifespan, the surrounding curb wood has been wet-and-dry hundreds of times, and the energy performance has dropped meaningfully from the original spec. Replacement becomes the rational choice.
- Replace if: IGU is fogged, you've had 3+ repairs, the curb shows soft spots, or you're getting a new roof anyway
- Replacement cost: $1,800–3,800 for a standard residential unit, $2,200–4,800 for a flat-roof unit. See skylight replacement Toronto
- Coordinate with roof: if your roof is also nearing end of life, do both projects together. The flashing and access savings can be 20–30% versus two separate jobs
The lifecycle in one table
| Age | What's happening | What you spend | Action |
|---|---|---|---|
| Year 1 | Bedding in, warranty period | $0 | Visual inspection, document with photos |
| Years 2–5 | Steady state, peak performance | $0 / occasional cleaning | Annual glass cleaning |
| Years 6–12 | First wear signs | $0–500 | Professional inspection at year 10 |
| Years 13–18 | Repair territory | $400–1,200 cumulative | Repair service as needed |
| Years 19–25 | End-of-life planning | $1,800–4,800 replacement | Plan replacement |
| Year 26+ | Bonus territory | Risk of major failure | Replace before failure |
Lifespan-by-product type
Not every skylight type ages at the same rate. The numbers above are for typical residential units; here's how the major categories vary:
- Fixed skylights — longest lifespan, fewest moving parts. 22–28 years typical. See fixed skylight options
- Vented manual — operator mechanism is the first thing to wear. 18–24 years
- Vented electric/solar — motor and electronics add complexity. 15–22 years on the mechanism, longer on the unit itself
- Sun tunnels — simpler construction, 22–30+ years. See sun tunnel skylights
- Flat-roof skylights — curb integrity is the key. 18–25 years. See flat-roof skylights
- Commercial dome units — depend heavily on glazing material; polycarbonate yellows in 12–18 years, acrylic in 15–20. See commercial skylights
What kills a skylight prematurely
The 25-year lifespan above assumes correct installation and basic maintenance. The things that cut it short:
- Cheap flashing. Field-bent metal instead of the manufacturer's flashing kit. Leaks within 3–5 years.
- Poor attic ventilation. Hot, moist attic air condenses on the cold underside of the skylight in winter. Frame rot is the result.
- Wrong unit for the roof. Sloped-roof units on flat roofs leak almost immediately. Always match the unit to the application.
- Skipping the ice-and-water shield. Required by Ontario Building Code in the eave zone. Some budget installers skip it around skylights too — disaster waiting.
- No annual maintenance. Five minutes a year of inspection prevents most premature failures.