Last reviewed October 31, 2026.
There is a brown ring on the ceiling under the skylight, and it gets a little bigger every nor’easter. Before anyone quotes you a new unit, it helps to know whether the water is coming around the skylight, through it, or from the air inside the house.
Leak, failed seal or condensation
Long Island roofers disagree a little on where most skylight leaks start, so treat each cause as a suspect:
- Flashing. Expressway Roofing & Chimney says flashing problems cause the majority of skylight leaks. Rapid Roofing says the metal flashing can corrode, warp or separate from the roof in freeze-thaw cycles, and SkyLuxe Construction says leaks often get worse in wind-driven rain.
- The unit’s own seal. VELUX says a leak usually means a problem with the window sealant, and Expressway notes that seals fail on older units.
- Ice. SkyLuxe says snow that melts and refreezes around the skylight can push water back up under the flashing. Our ice dams guide covers why that happens.
- Condensation. VELUX says condensation is not a leak, comes from indoor humidity meeting cold glass, and is excluded from its warranty. Its advice for a venting skylight is to open it for five minutes, three or four times a day.
What skylight work costs here
| Job | Published price | Source |
|---|---|---|
| Inspection | $75 to $250 | Rapid Roofing (Jan 2026) |
| Reseal or flashing repair | $450 to $1,500 | Expressway Roofing & Chimney (Sep 2026) |
| Repair, Suffolk County | $300 to $1,500 | SkyLuxe Construction |
| Replacement in the same opening | $1,200 to $3,000, Suffolk average about $2,300 to $2,400 | Expressway Roofing & Chimney (Sep 2026) |
| Full replacement | $2,000 to $5,300 | Rapid Roofing (Jan 2026) |
| Installed skylight, per unit | $1,000 to $4,000 | SkyLuxe Construction |
| New opening in the roof | $3,000 to $5,500 | Expressway Roofing & Chimney (Sep 2026) |
| Install or repair, priced with a roof job | $800 to $2,500 each | EZ Roofing & Builders |
| New flashing kit during a roof replacement | $400 to $1,200 each | LI Roofing Co. (May 2025) |
| Tubular skylight, installed | $600 to $1,100 | Expressway Roofing & Chimney (May 2026) |
SkyLuxe breaks a typical install into $500 to $2,500 for the skylight and $500 to $1,500 for the labor, and says fixed skylights cost less than venting ones. A new opening costs more because, as Solatube puts it, it is a roof, framing, drywall and paint project all at once.
VELUX models and what they list for
VELUX publishes its own installed-price estimates for the four versions of its deck-mounted skylight. They are national figures, so set them next to the local quotes above:
| VELUX model | New installation | Replacement |
|---|---|---|
| Fixed (FS) | $1,900 to $4,200 | $900 to $2,400 |
| Manual venting (VS) | $2,100 to $4,600 | $1,200 to $2,700 |
| Electric venting (VSE) | $2,900 to $5,800 | $2,100 to $3,600 |
| Solar venting (VSS) | $2,900 to $5,800 | $2,100 to $3,600 |
The solar model needs no wiring: a small panel charges a battery, and a rain sensor closes the skylight at the first sign of rain. VELUX’s weathertight system is three layers, a deck seal on the frame, an adhesive underlayment and its own engineered flashing.
Tubular skylights for a dark hallway
A tubular skylight, or sun tunnel, runs a reflective tube from a small dome on the roof down to a ceiling fixture. It brings in light but no view and no fresh air. Solatube says most of its residential units go in in under two hours and averages $900 to $1,200 installed, against about $2,500 to $4,500 for a standard 2 by 4 foot skylight. Expressway’s Long Island range for tubular units is $600 to $1,100.
Warranty details that decide who pays for a leak
VELUX’s skylights carry a 10-year installation warranty when installed with VELUX flashing, plus 20 years on the glass, 10 on the product and 5 on shades and controls. Its warranty explainer lists exclusions worth knowing before you sign anything:
- condensation
- ice damming that pushes water in
- re-roofing without re-wrapping the skylight in VELUX adhesive underlayment and VELUX flashing
That last one matters most. A roofer who shingles around your old skylight and reuses its flashing can void the coverage. VELUX recommends replacing skylights when you reroof so the skylight and roof warranties start together, and says its skylights can last 20 to 30 years. Expressway gives a well-installed skylight 20 to 25 years, and Rapid Roofing 15 to 25.
Skylight permits and the building code
The Town of Islip requires a building permit for a skylight wider than 15 inches or any job that modifies rafters. For roof work generally, Islip requires no permit unless structural elements are changed. Other towns and villages set their own rules, so check with yours before the roof is cut.
The 2025 Residential Code of New York State, Section R324.6, limits skylight glass to laminated, fully tempered, heat-strengthened or wired glass, or approved rigid plastic. Tempered or heat-strengthened glass needs a broken-glass screen below it unless the inner pane is laminated. On a roof flatter than 3 in 12, the skylight has to sit on a curb at least 4 inches above the roof unless the manufacturer’s instructions say otherwise.
The federal solar tax credit is gone for 2026 installs: the IRS says the Residential Clean Energy Credit is not available for property placed in service after December 31, 2025. Some local pages still advertise it.
