All About the Different Types of Skylights
Skylights bring natural light into areas that normally wouldn’t have windows. They come in a range of designs. Check out the three standard types of skylights that are used—ventilating, fixed and tubular.
Converting an attic into a habitable area needs a permit and building inspections because most attic floors are not designed for the added load living space requires. If the area is to be used as a bedroom, it must have a window or other direct route to the exterior for emergency escape. A complying stairway must be provided to the habitable area.
Ventilating windows are installed at the same pitch as the roof, so no other roof structure needs to be built in order to accommodate the window. Access for maintenance is also easier with a tilting design and remote controls are available for operation. Because of the ease of installation and upkeep, you can install pivot windows when you renovate other areas. The success of this type of window design has expanded product ranges. In addition to standard tilting windows, it is now possible to buy top- or side-hung variations, as well as specially designed blinds and shutters. These may attach to the inside of the window, or sit between two panes of glass inside the window itself.
Planning and Permits
Standard sizes of tilt windows are available, or several windows can be placed alongside each other to make a larger window space — although this may affect the structural integrity of the roof. Before buying the window, seek professional advice. Any required cuts in rafters will weaken the roof structure and will require additional framing. Planning permission is sometimes required for this type of window, and there may be local regulations governing a window’s size, its position in the roof, and even its design.
Installing a Skylight
Three different designs of windows, all of which are installed using much the same technique, include tilt, fixed and escape window. One major advantage of tilt windows is that the installation process can be carried out entirely from inside the roof space. Unless you are adding a very small window that can sit between rafters, at least one rafter will need to be cut to make room. To ensure this does not weaken the roof, support members called false rafters and trimmers will have to be inserted to strengthen the opening. The way in which rafters are cut and trimmers are inserted is very much dependent on window size and positioning. The three examples below are aesthetically quite different, but structurally similar.
Tilt Window (image 1)
This is a variation on a straightforward design. The window opens from an upper hinge instead of tilting around the central window axis.
Waterproofing (image 2)
Tilting roof windows are installed in conjunction with flashing kits to make sure the window is waterproof. Flashing kits vary not only with window size and design, but also according to the type of roof shingles.
Fixed (image 3)
Fixed skylights do not provide exterior access, but offer additional light and the opportunity to enjoy views outside.
By hinging the window along its side, it can easily be “thrown” open, for use with an emergency ladder if required.
Skylights are not limited to just the rooms in your attic. When you want to brighten a room that is too small to install a wall window or is simply lacking direct access to the roof to allow traditional skylight installation, there still remains another option to bring natural light in. Tubular skylights are installed using a shaft that starts at the roof and extends down through your home. Capturing sunlight on the rooftop, the tube redirects it down a highly reflective shaft, and diffuses it throughout the interior space. Unlike the direct light of a skylight, tubular skylight uses a type of optics that spread the light out over more floor surface area. The tube can also be angled around attic obstructions.
Tubes are available in a range of sizes. The model shown below is offered in diameters of 10, 14, or 21 inches. The 10- and 14-inch models can easily fit between rafters and ceiling joists so no structural modifications are needed. Such units also offer the Energy Star® rating, designating them as offering optimal energy efficiency. Because of their compact size, tubular skylights are ideal in smaller areas where traditional skylights couldn't be accommodated, such as powder rooms, shower stalls, hallways, and walk-in closets.
These skylights have optional features that are available from manufacturers. Integrated bathroom fans are an optional feature, ideal for use in bathrooms and laundry rooms. Electric light kits can be used to modify the unit, allowing you to use the tube at night as an additional light fixture. There is also a dimmer that allows you to adjust the level of daylight that pours through the tube. The entire unit is sealed to lock out dust, bugs, and moisture.
Tubular Skylight Installation (image below)
When installing a tubular skylight, start by marking the location inside the room. Line up the preferred location with a flat area in the roof before cutting any holes.
Flashing and Installation
The National Roofing Contractors Association recommends that skylights are flashed just as chimneys with a separate apron, step, cricket or back flashing and counterflashing. Some skylights are called "self-flashing," meaning typically continuous flashing is prefabricated as part of the unit. Step flashing may also be needed.
If you see condensation forming on your skylight's interior, it may not be a leak. Condensation may occur if an inadequate amount of insulation is used along a skylight's sides.
Windows can also be added to flat roofs to provide more light. These are often built up on a frame above the main roof deck, and tilted to allow for runoff. Because of the location, installation is straightforward — you can work directly from the roof deck.
There are a number of factors to consider when converting an attic. One of the most important issues is how much structural work will be needed. If the existing joists are not substantial enough to support a floor, they will require strengthening. If roof-support trusses cross the area you want to use, you may have to alter the roof’s structural framework to remove them. Other important considerations include the number and type of windows, and where the stair access will enter the loft from below. You may need to reshingle parts of the roof before or during conversion, and will certainly need to reroute some electrical supplies, and possibly heating, air conditioning, and plumbing as well. One other major thing to consider is stair access and how you will move the building materials into your roof space, and get access to it while you are working.