---
title: "Skylight and Roof Penetration Repair in Ontario | flat-roof-repair.ca"
description: "Skylight, vent, pipe and curb reflashing on flat roofs in Ontario. Fix leaks at roof openings and rooftop equipment without replacing the whole roof."
url: https://flat-roof-repair.ca/services/skylight-and-penetration-repair/
last_updated: 2026-10-23
---

# Skylight and penetration repair

Skylights, plumbing vents, exhaust fans and rooftop units all pass through the membrane. Each one needs its own watertight detail, and each one eventually needs attention.

## Why openings leak

A skylight leak is often blamed on the glass. More often the problem is the curb: the raised frame the skylight sits on, and the flashing that ties it to the roof. Condensation inside the unit can also look like a leak, so the first job is to tell the two apart.

Pipes and vents leak where the rubber boot cracks in the sun and cold, or where a collar was never sealed to the membrane. Rooftop units leak where their curbs and cable or pipe pass-throughs were poorly flashed.

## What we work on

- **Skylight curbs**: Reflashing the curb with membrane turned up and capped, so the skylight sits on a dry base.
- **Skylight units**: Resealing or replacing a failed unit where the glazing or frame is the cause. Large or custom glazing is quoted separately.
- **Plumbing vents and pipes**: New boots, collars and field-formed flashings in place of cracked rubber.
- **Exhaust and intake vents**: Sealing and flashing the curb and cap.
- **Rooftop unit curbs**: Reflashing around HVAC curbs and the lines that enter them. See [office buildings](https://flat-roof-repair.ca/property-types/office-buildings/) and [retail plazas](https://flat-roof-repair.ca/property-types/retail-plazas/).
- **Hatches and access**: Roof hatch curbs and the seals around them.

## How a repair goes

- **Diagnose**: Confirm whether the water comes from the flashing, the unit or condensation. A hose test helps where it is safe.
- **Prepare the curb**: Remove failed flashing and sealant, check the curb for rot, and clean the membrane.
- **Reflash**: New membrane flashing on all four sides, with corners properly formed.
- **Cap and seal**: Metal or membrane cap, termination, and a final check of fasteners and edges.

## Opening and curb pricing

| Item | Starting price |
|---|---|
| Skylight, curb or vent reflashing | from $350 per opening |
| [Flashing repair or replacement](https://flat-roof-repair.ca/services/flashing-and-seam-repair/) | from $500 per repair |
| [Small leak repair (patch, seam or puncture)](https://flat-roof-repair.ca/services/flat-roof-leak-repair/) | from $350 per repair |

Starting prices in CAD before 13% HST, based on typical Ontario contractor rates (mostly Toronto and the GTA). The final price depends on roof size, access, the layers to remove, the membrane, drains and flashings, and is confirmed in your written quote.

The price is per opening. Large curbs, damaged framing and units that need replacing are priced after we see them.

## Planning a re-roof anyway?

Skylights and penetrations are cheapest to reflash during a replacement, when the membrane is open around them. If your roof is near the end of its life, ask for the skylight work to be included in a [replacement](https://flat-roof-repair.ca/services/flat-roof-replacement/) quote.

[See replacement options](https://flat-roof-repair.ca/services/flat-roof-replacement/)

## Questions about skylight and vent leaks

**How do I tell condensation from a leak?**

Condensation forms on the inside glass in cold weather and drips along the same edge each time. A leak shows after rain or melt, often with staining on the surrounding drywall.

**Can you replace my skylight?**

We repair and reflash the curb and, where the unit has failed, replace it. Glazing choices and interior finishing may be done by a skylight specialist.

**Can I add a new skylight to a flat roof?**

Often yes, with a properly built curb and flashing, but it involves cutting the structure. Ask your builder or designer first.

## Related

- [Flashing leaks](https://flat-roof-repair.ca/problems/flashing-leaks/)
- [Flashing and seam repair](https://flat-roof-repair.ca/services/flashing-and-seam-repair/)
- [Flat roofs on houses](https://flat-roof-repair.ca/property-types/houses/)
- [Finding a flat roof leak](https://flat-roof-repair.ca/guides/finding-a-flat-roof-leak/)

---

Get a quote: https://flat-roof-repair.ca/request-a-quote/ · Email: info@flat-roof-repair.ca