Venting - Will open and close, like awning windows, to provide fresh air. May be operated by hand, or be electric with remote control. Units with sensors to close during inclement weather are available.
Fixed - Will not open and close
Roof Window - depends upon the manufacturer, but skylights that open and “pivot” to provide a larger opening and to enable cleaning the outside may be called roof windows. Some manufacturers refer to all skylight options as roof windows, while others call their venting units roof windows. Read manufacturer catalogs and listings for their terminology.
Chase - A tunnel constructed from the skylight through the attic to the room below. The chase walls may be straight, angled or even flared to direct the sunlight and any fresh air, and to provide the view to the sky.
Flashing - Material used to deter water infiltration around protuberances in sheathing, such as windows in walls and skylights or vents in roofs.
Curb - A raised lip surrounding the skylight to deflect water around the unit.
Glazing - Glass or plastics are used in skylights for the viewing area. These units are constructed in single, double, or triple pane varieties. Double and triple pane skylights may opt to have argon gas between the panes to increase the energy efficiency. The glazing can be flat, domed, arched or created into shapes such as pyramids or barrels.
Tempered Glass - Treated by heating and cooling or with chemicals to safety standards. The glass is stronger to resist winds and debris that may hit the skylight. Should it break, tempered glass is designed to create small pieces that will be less damaging if they fall.
Laminated Glass - Two or more panes of glass are bonded with an interlayer of resilient plastic. Used in skylights to diminish fracturing of the panes from storm damage. If the glass breaks, minimal chips of glass will fall into the room below as it will adhere to the plastic laminate.Low-E coatings reduce heat transfer from the outside in, and from the inside out.
U-Factor - The measure of heat transference in a window or skylight. The lower the U-factor, the more energy efficient the unit.
Solar Heat Gain Coefficient (SHGC) - The effectiveness of the skylight in reducing heat from sunlight entering the room.
Visible Light Transmittance - Measurement of the amount of daylight a skylight transmits. To block damaging UV rays, a tinted glazing may be added to the glass or plastic panes. This will block the amount of sunlight into the area below.
Tubular Skylight or Tubular Daylighting Device (TDD) - Designed to provide sunlight through the roof into an area below through a tubular chase, which is treated with a reflective interior coating.