Skylights consist of metal-framed units, Roof Windows, and Sloped Glazing Systems. They are a great way to introduce to light and solar heat gain to a building interior in the winter. They’re also a great way to beautify a room with more visuals of the outdoors. The downsides of skylights are their tendency to allow solar heat gain in summer and their heightened vulnerability for leakage. Also, brightness and glare must be addressed and controlled with louvers, shades, reflector panels, or tinting. Skylight glazing is most commonly acrylic, polycarbonate plastic, wired glass, laminated glass, heat strengthened glass, or tempered glass, or a combination therof. Some have claimed that plastic skylights, while often less expensive, are more prone to leakage, are less energy efficient, and allow excessive UV light to penetrate which can discolor items in the room. Building codes will commonly govern a maximum square footage allowed for skylights for safety purposes.
When installing a skylight system, an opening must be framed out to properly support the skylight structurally and to simplify flashing. Part of the flashing system should incorporate drainage channels as well which channel or gutter the water away from the window. Also the rough opening should be flashed as well to keep moisture from penetrating the ceiling assembly. Some skylights will require a built ‘curb’ on which the skylight sits, particularly for lower sloped roofs which makes installation easier, makes flashing simpler, and improves overall moisture control.
When a skylight system is chosen, a good rule of thumb for sizing to skylit square footage is Square Foot of Room / 20.
Skylights – Most commonly metal framed unit windows glazed from plastic or glass panes which have crucial flashing systems that must be followed. There are stock sizes available but custom sizes are typically available as well.
Roof Windows – Typically wood framed but can be metal as well, and are made primarily for use on sloped roofs. They commonly swing open for air flow and cleaning. Common width is 2′ – 4′ and heights of 3′ – 6′. They are typically offered with the option of blinds, shades, or electric operating systems.
Sloped Roof Glazing Systems – Also referred to as glazed roof curtain walls which are similar to the vertical systems but are designed for roofs.