Deck Mounted, Curb Mounted and Self-Flashed Skylights

Common flat rectangular skylights can be deck mounted or curb mounted. The main difference is that the curb mounted skylights (which can be self-flashed or not) involve a raised frame (a curb) while the structure of deck mounted skylights is attached directly on the deck of the roof.

Deck mounted skylights

A deck mounted skylight is attached directly to the roof deck. Typical structures combine a wood or aluminum frame, an insulated glass pane and protective cladding and accessories. A flashing kit makes the installation water-tight.

Curb mounted skylights

A curb mounted skylight comprises a site built curb – which is but a raised frame, often made from wood or aluminum, to which the skylight is attached to. The curb goal is to raise the skylight above the roof plane to get an increased protection against water and ice. Insulated glass panes (and rubber gaskets to seal the skylight) are attached to the curb. The system involves also a flashing kit.

Curb-mounted skylights are the commonest type of skylight in cold, rainy climates. Manufacturers offer solutions to work with most types of site-built curbs.

Deck mounted… self-flashed skylights

Self-flashed skylights are a variant of deck mounted skylights. In self-flashed skylights the flashing kit is factory installed and factory-attached to the glass panes (instead of being a separate unit). Self-flashed skylights are mainly used on shingle roofs.

Curb Mounted versus Deck Mounted skylights

Whenever there is the risk of the skylight being immersed by water with consequent leakage, a curb mounted skylight is preferable to a deck mounted one: flat roofs and roofs with a small slope require a curb mounted skylight…

In other situations, the alternative curb mounted vs. deck mounted skylight is rather dependent on personal preferences.

Self-flashed or separated-flashed skylights

A good and well installed self-flashed skylight, with factory-installed flashing, is a common and easy installing option for deck-mounted skylights (typically shingle roofs). But you may prefer separated flashings… There isn’t exactly a better option: the final result depends on the details concerning the flashing, assemblage and installation.