Skylight Installation
IN PA, OH & WV

A correctly installed skylight on a sound roof should not leak, and the honest caveat is that a skylight is still a hole cut through the one surface of your house whose entire job is keeping water out. Almost every leak we see traces to flashing or to a failed glazing seal — not to the skylight itself being a bad idea. Three things separate the ones that leak from the ones that do not: the manufacturer’s flashing kit matched to the unit and to your roofing material, ice-and-water shield underneath, and correct lapping with the shingle courses. There is also a fourth thing people mistake for a leak, and that is condensation — water on the inside of the glass on a cold morning is a ventilation and humidity issue, not a roof failure.

Curb-mounted sits on a raised wooden frame above the roof surface and is the more weather-tolerant of the two, especially where snow sits. Deck-mounted sits flush with the roof, looks lower and cleaner, and is the more common choice on steeper pitches. The difference that matters most in this climate is replacement. When a curb-mounted unit reaches the end of its life, it unscrews off the curb without touching the surrounding roof. A deck-mounted unit generally means re-roofing the area around it. On low-slope roofs and in the snowbelt we lean curb-mounted for that reason; on a steep pitch where appearance drives the decision, deck-mounted installed with the factory flashing kit performs well.

A quality unit installed correctly lasts roughly 25 to 30 years, which is close to the life of the roof around it. What usually fails first is the seal between the glass and the frame, not the flashing or the glass. That timeline is the reason we raise skylights whenever we quote a roof replacement. If the unit is fifteen or twenty years old, removing and re-setting it during a re-roof frequently breaks seals that were already UV-degraded, and the skylight starts leaking on a roof that is brand new. Replacing the unit with the roof costs a fraction of doing it separately two years later.

For a room that has no other way to get daylight — an interior bathroom, a stairwell, a north-facing kitchen, a finished attic — usually yes. For a room that already has decent windows, the case is much weaker and we will say so. The honest trade-offs: a skylight is a thermal weak point in the roof and a venting unit adds a mechanical part that can fail. Placement matters more than product. South-facing glass in a room that already runs warm creates a problem you then pay to solve with shades. We would rather talk through the room before quoting the unit.

Because two quotes for “a skylight” are often for very different jobs. A fixed unit going into an existing opening is not the same work as cutting a new opening through rafters, framing it, and building a light shaft down through an insulated attic to the ceiling below. The variables are the unit itself (fixed, venting, solar-powered blinds, glazing spec), whether framing has to be altered, the length and finish of the shaft, and whether it is going into a roof that is being replaced anyway. The cheapest line item on a quote is usually the one that skipped the factory flashing kit — that is what the warranty depends on, and it is the single most common reason a new skylight leaks.