Velux-type and custom skylights, supplied and installed with the roof opening curbed, flashed and made watertight
A skylight is a window in the roof, and it lives a harder life than any window in a wall. It faces the sky, so it takes direct sun, ponded rain and snow load; it sits in the roof membrane, so its perimeter is the most likely leak in the building; and it is hard to reach, so whatever goes wrong is expensive to fix. We supply Velux-type unit skylights and custom-sized units, and we install them with the roof opening cut, curbed, flashed and tied into the waterproofing as one piece of work, because a skylight that is installed by one trade and flashed by another is a skylight that leaks.
Glass in a roof is treated differently from glass in a wall, for an obvious reason: if it breaks, it falls on whoever is underneath. Building Code §2405 governs any glazing sloped more than 15 degrees from vertical, which is every skylight. The practical rule is that the glass must either be laminated — with a polyvinyl butyral interlayer of at least 30 mil, so that a broken pane stays together in the frame — or, if it is tempered or heat-strengthened, it must have a retention screen fixed below it within four inches of the glass. There is a narrower residential exception that allows a 15-mil interlayer for small panes close to the floor. Either way, a plain tempered skylight with nothing beneath it is not compliant, whatever the price tag says, and we specify laminated inner panes as standard so the question never comes up.
The same section sets the curb rule: a unit skylight on a roof pitched flatter than 14 degrees sits on a curb at least four inches above the roof plane, unless the manufacturer's instructions say otherwise. On a flat New York roof that means every skylight is on a curb, and the curb is where the waterproofing succeeds or fails.
A well-made skylight is factory-sealed and rarely fails on its own. The leaks we are called to look at are almost always at the curb: a membrane that stops short, a flashing lapped the wrong way, sealant doing a job that only a flashing can do. That is why we do not install skylights into openings someone else has prepared. We cut the opening, build and insulate the curb, run the roof membrane up and over it, set the unit, and counter-flash, so that one crew is responsible for the whole penetration. See waterproofing for the materials we use.
The honest caveat: a skylight adds heat in summer and loses it in winter faster than the roof around it, and no coating changes that entirely. Where the room does not need the light — a hallway with windows, a bedroom that would be too bright — the right answer is often no skylight. Where it does, a solar-control low-e unit on the sunny slopes and a venting unit over a kitchen or bathroom earn their cost.
Send us a photograph of the roof and the room below it, and the rough opening size, and we will tell you which unit fits and what the curb and flashing need to be
