Selecting Skylights

Installing SkylightsIf you had to choose one word to define a room with a skylight, a good word might be dramatic. The benefits of natural light to people and houseplants are well known. Skylights provide more natural light than vertical windows (up to 30%). From a design perspective, they can actually make a room feel bigger. Skylights are available for any ceiling or roof style.

Skylight Types

The term skylight or roof window is often used to describe several styles.

Ventilating skylights are excellent for bath or kitchen. In addition to providing extra light, when opened, the overhead ventilation creates an updraft. Ventilated skylights can be operated by several means:

  • Controlled by temperature sensor
  • Remote control
  • Electric on/off wall switch
  • Manual or motorized hand crank

Fixed skylights are for additional light only. They’re great for attics, bonus rooms or anywhere you want extra illumination or to enjoy the view. Styles and sizes vary from domes to rectangles. Acrylic skylights are available for utility rooms, workshops and garages where fashion is less of a concern than functionality.

Tubular skylights are relatively new on the scene. The small size (normally a 10-inch or 14-inch diameter) allows them it to be used in spaces where full-sized skylights cannot. Hallways, bathrooms, even closets can accommodate a tubular skylight. They provide a lot of light in spite of their small size. The concept and installation process are basically the same as for a regular skylight.

Skylight Features

Here are some extras you might want to look for when selecting a skylight: Insulated thermal glass prevents loss of heat in winter and assists cooling in summer. Tinting filters UV rays and additional heat. Shades or blinds screen full sun — a good idea as the sun tracks through the room during the day. Insect screens on ventilating skylights keep pests outdoors where they belong.

Before You Buy

Rafters vs. Trusses
You need to be familiar with the roof and ceiling in your home. Make sure you know your roof support system when you go shopping. Take a look in the attic and compare to the illustration. Your roof support joists should be either 16" or 24" on centre. The simplest installation occurs when the skylight fits between two roof joists. Skylights that are larger than the joist measurements can be installed but require reinforcing. Know what kind of roof you have. The roof thickness determines the type of mounting and flashing required. Thinner roofs like asphalt or fibreglass use self-flashing or curb mount. Thicker, higher-profile roofs such as wood shakes, slate or clay tile require built-up curb and flashing.

  • Self-flashing – prefabricated part of the unit. The skylight drops in and installs right into the roof.
  • Curb-mount – site-built to accommodate window and roof thickness. The skylight is then mounted to the curbing.

Safety Note: Never cut rafters or trusses without first consulting an engineer or structural expert.

The type of ceiling you have dictates whether or not you need a shaft to direct light into the room.

  • Cathedral ceiling skylights mount right in the roof. One hole does it all.
  • A regular ceiling needs either a straight or flared shaft.

A flared shaft directs more light into the room. With either shaft you’ll have to cut and frame two holes — one in the ceiling and in the roof. Reflective shafts increase the light provided. Remember that shafts need insulating to prevent heat loss. Follow manufacturer’s instructions.

If You Plan to Install It Yourself

  • The old adage “measure twice, cut once” applies. Unless you ’re comfortable cutting holes in your roof, you may want to measure three times when putting in a skylight.
  • Always check for wiring before cutting anything.
  • Check the weather forecast.
  • Get a helper.