Insulated glass mounted flush with the roof in a low-cost, site-built design.
Synopsis: Curbless skylights are set flush with the plane of the roof. This article explains how to make them. Illustrations cover flashing and installation details. The author is Rob Thallon, an architect and builder who has written three authoritative books on residential construction.
Builders find themselves installing lots of skylights these days. There are some excellent manufactured skylights on the market, the best of which are well insulated and can be opened for ventilation and cleaning. These top-of-the-line units are expensive—$25 per sq. ft. or so. Less costly store-bought skylights are not operable, usually not insulated, and they are often translucent rather than transparent. Some of these budget skylights come with an attached, preflashed curb to raise the glazing above the roof, but many require on-site curb construction.
The curbless skylights that I started to build about nine years ago are installed more like large shingles, in contrast to most of the manufactured or site-built skylights that I’ve seen. Eliminating the curb gives the skylight a lower profile so that it looks more continuous with the roof.
In the last six years my partner, David Edrington, and I have installed more than 50 curbless skylights, and they’ve held up well. We use insulated, tempered-glass panels in standard sizes when possible, and we’ve simplified construction details to the point that we now feel confident that our skylights are the best fixed skylights available.
Our design can accommodate just about any type of glass or acrylic panel (providing you allow extra room for expansion), and replacing the glass is an easy job. The design doesn’t rely on caulks and sealants, which have unpredictable lives, but rather on the behavior of water in contact with metal and glass. With slightly different flashing details, these skylights can be ganged to form continuous…