Fogging between the panes
The glazing seal has failed. The skylight is still watertight but has lost its insulation value and looks tired.
Roofing · Skylights and sun tunnels
Skylights and sun tunnels
A skylight is a hole in the roof with a window in it, so the roofer matters more than the brand. Done well, with the right curb, flashing kit and underlayment, a skylight is as dry as the rest of the roof. The cheapest time to replace or add one is while the roof is being redone, when the flashing can be built into the new roofing rather than cut into the old.
- Replace during a re-roof about $900 to $1,800
- New fixed skylight about $1,500 to $4,500
- Venting skylight about $1,200 to $4,000
- Sun tunnel about $800 to $2,000
Warning signs
How serious is it?
Staining around the skylight shaft
Water is getting past the flashing or the unit. Often repairable, but on an old roof it's usually time to replace both.
Condensation dripping on cold nights
Usually warm indoor air meeting cold glass, not a leak. Ventilation and better glazing fix it.
Dripping during rain
Flashing or seal failure. Tarp it, then repair or replace.
Roof being replaced and the skylight is over 15 years old
Replace it with the roof. It adds a few hundred dollars now and saves cutting into a new roof later.
Options
Skylight options
| Option | What it is | Good for |
|---|---|---|
| Replace during a re-roof | The old unit comes out, a new deck-mounted or curb-mounted skylight goes in with the manufacturer's flashing kit, built into the new roofing. | Any skylight over 15 years old when the roof is being replaced. |
| New fixed skylight | A new opening framed, the skylight installed and flashed, the shaft finished inside. | Dark kitchens, bathrooms and stairwells. Fixed units cost less and leak less than venting ones. |
| Venting skylight | Opens manually or electrically, often with a rain sensor. | Bathrooms and kitchens that need to shed steam and heat. |
| Sun tunnel | A small roof dome with a reflective tube to a ceiling diffuser. | Hallways, closets and rooms where a full skylight shaft isn't practical. |
| Reflash or reseal | New flashing kit or seals on an existing skylight. | Leaks around a newer skylight on a roof with years left. |
Local conditions
Why old skylights leak
Most skylights installed in the 1980s and 90s have long outlived their seals. The glazing fogs, the flashing was often site-bent and sealed with caulking, and the roofing around them has been patched. When a 25-year-old roof is replaced, reusing a 25-year-old skylight is asking for the only leak in a new roof. Replacing it adds a few hundred dollars to the job.
Condensation is the other complaint: on cold clear nights warm indoor air hits the cold glass and drips. That's often ventilation and glazing, not a roof leak, and a roofer will tell you which it is.
What a good quote includes
- Model, glazing (double, laminated, low-e) and whether it's fixed or venting
- Deck-mounted or curb-mounted, with the manufacturer's flashing kit
- Ice and water membrane around the opening
- Interior finishing of the shaft, if the opening is new
- Disposal of the old unit and matching the roofing around it
- Manufacturer warranty on the glass and seals, plus the roofer's workmanship warranty
Watch for: Reusing an old skylight on a new roof, or flashing it with caulking and roofing cement instead of a flashing kit.
Costs
Typical skylights and sun tunnels prices
| Job | Typical range | What moves the price |
|---|---|---|
| Replace a skylight during a re-roof | $900 to $1,800 | Like-for-like fixed unit with a new flashing kit |
| New fixed skylight | $1,500 to $4,500 | New opening, flashing and interior shaft finishing |
| Venting skylight | $1,200 to $4,000 | Manual at the low end, electric with rain sensor at the high end |
| Sun tunnel | $800 to $2,000 | Small dome and reflective tube to a ceiling diffuser |
| Reflash or reseal an existing skylight | $350 to $1,200 | New flashing kit or seals |
Budget ranges in CAD before GST, from prices published by Lower Mainland roofers in October 2026. Your quotes are based on a site visit.
Questions
Skylights and sun tunnels questions
Should I replace the skylight when I replace the roof?
If it's more than 15 years old, yes. A like-for-like replacement adds about $900 to $1,800 while the roof is off, and the new flashing kit is built into the new roofing. Cutting a new roof open later costs more and risks leaks.
Why does my skylight drip on cold nights?
Usually condensation: warm, moist indoor air meets cold glass and runs down the frame. Better glazing, a vented unit or improving bathroom and kitchen ventilation fixes it. A roofer can tell condensation from a flashing leak.
Fixed or venting?
Fixed skylights cost less and have fewer seals to fail, and suit most rooms. Venting units make sense in bathrooms and kitchens where you want to shed steam and heat.
What's a sun tunnel?
A small dome on the roof connected to a ceiling diffuser by a reflective tube. It brings daylight into hallways, closets and bathrooms where a full skylight shaft isn't practical, for about $800 to $2,000 installed.
Often done together
Skylights and sun tunnels by area
Metro Vancouver
- Vancouver →
- Surrey →
- Burnaby →
- North Vancouver →
- Coquitlam →
- Delta →
- Richmond →
- West Vancouver →
- White Rock →
- Port Coquitlam →
- New Westminster →
- Port Moody →
Fraser Valley
- Chilliwack →
- Abbotsford →
- Langley →
- Maple Ridge →
- Mission →
- Pitt Meadows →
- Hope →
- Agassiz →
- Harrison Hot Springs →
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