Five minutes of inspection per season, plus one professional check every 5 years, is the difference between a 25-year skylight and an 18-year skylight. Toronto's climate is harder on skylights than most North American cities — the freeze-thaw cycle alone puts a unit through 60+ stress cycles a year. This checklist covers the moves that actually matter.
Spring — the post-winter check
After Toronto's winter, the skylight has just survived its hardest 4 months. Spring is when most damage from ice-and-thaw becomes visible. Walk through these:
- Exterior glass — clean with mild soap and water. Inspect for hairline cracks (rare but possible after a hailstorm)
- Flashing — look for any lifted or curled metal pieces around the curb. Pay attention to where the up-slope flashing meets the shingles
- Sealants — check for cracking, peeling, or daylight visible at any seam. Caulking that has dried out and pulled away from the metal is the most common issue
- Interior ceiling and shaft — look for any new water stains, paint bubbling, or drywall softening that wasn't there in the fall
- Vented unit operation — open and close once if it's a manual or electric vented unit. Listen for grinding, sticking, or unusual noises
If any of these show issues, get a repair inspection booked before the spring rain season starts. Small issues in April become big ones in May.
Summer — the dry-weather window
Summer is the easiest season for skylights. Dry weather, predictable temperatures, no ice. But it's also the best window for repairs, replacements, or new installations because the work doesn't fight the weather.
- Glass cleaning (annual) — by midsummer, accumulated pollen, dust, and bird droppings are visible. Clean from inside if accessible, or from the roof if you have safe access. Better to hire someone than fall
- Shade and blind operation — if you have manual or motorized blinds, run them through a full open/close cycle
- Skylight glass UV check — note any change in tint or any visible UV degradation. Older units (year 15+) sometimes show yellowing
- Plan major work — if you've been thinking about replacement, sun tunnel addition, or new install, summer is the prime window. Book by mid-July to get on a contractor's schedule
Fall — pre-winter preparation
The most important inspection of the year. Anything not fixed before winter has to wait until March, and may cause damage in the meantime. See the winter prep guide for the full pre-freeze checklist.
- Clear debris from around the curb — leaves, twigs, and shingle granules that accumulated around the skylight need to be removed before they trap moisture
- Inspect attic from underneath — look at the skylight shaft from the attic side. Any signs of moisture, staining, or condensation are warning signs
- Check attic ventilation — proper soffit intake and ridge venting is what keeps the underside of the skylight from condensing. Most premature skylight failures trace back to poor attic ventilation. See winter prep page for details
- Test the seal — on a cool morning, run your hand around the interior frame. Any cold draft means a gasket issue that should be fixed before winter
- Eavestrough cleanout — clogged gutters cause water to back up under the eave shingles, which can affect skylights in the lower part of the roof
Winter — minimal intervention
The wrong season to be on a roof. The work in winter is observational, not hands-on:
- Monitor for ice dams — look from the ground after a thaw-freeze cycle. Ice ridges at the eaves means meltwater is being trapped, which can affect skylights in the lower zone
- Watch for condensation on interior glass — a little on cold mornings is normal. Persistent or heavy condensation means a humidity or ventilation issue inside the home
- Document any leaks immediately — date-stamp the photos. You'll want them for the spring repair conversation
- Emergency contact ready — keep emergency skylight repair contact info handy in case a winter storm causes active leakage
Every 5 years — professional inspection
A $150–250 professional inspection every 5 years catches issues you'll miss from the ground. What a real inspection covers:
- Roof-level visual of all flashing, sealants, and curb integrity
- Attic-side inspection for moisture, ventilation, and structural condition
- Operating mechanism check on vented units
- Glass and seal condition — looking for early signs of IGU failure
- Written report with photos for your records
For Toronto-area homeowners, the team at Toronto Skylight Installers handles these as part of standard service. Worth doing at year 10, year 15, and year 20 minimum.
The annual cost framing
A well-maintained skylight costs roughly $50–150/year over its lifetime when you average out cleaning, occasional repairs, and the eventual replacement. That's almost exactly what a window costs to maintain, plus you get the daylight and ventilation. Skipping maintenance saves $0 per year — but accelerates replacement by 5–8 years, which costs $1,800–4,800 in advance.
Common DIY mistakes
- Pressure-washing the exterior — strips sealant, damages flashing. Use a soft brush and mild soap
- Caulking over old caulking — old caulk has to come off first, otherwise the new layer doesn't bond
- Painting the interior shaft a dark color — kills the light-amplification benefit. Stick to white or off-white
- Ignoring small leaks — a tiny stain becomes a major repair when the deck below rots out
- Walking on the skylight — common roofer mistake, sometimes a homeowner one. The unit is not load-rated for a person