7 Things to Consider Before Starting a Skylight Installation
Impress your installer and achieve glowing results by keeping these skylight project planning tips top of mind.
Need a little extra light in your life? Consider installing a skylight above an interior room that’s low on natural light. These roof windows let in up to five times more light than a sidewall window and plenty of warmth. The cost and complexity of installing one, however, make it well worth your time to educate yourself on the structural conditions you need to meet and the design decisions you need to make to get a skylight that works for you. Factor in these seven project considerations before giving your contractor the green light on a skylight installation.
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1. Skylights aren’t right for all roofs.
Because skylights are installed at the roofline beneath the roof shingles and sheathing, the construction of the roof must be able to support the skylight. First, consider the framing, which typically is one of two types:
- Stick-framed roofs, built with individual rafters spaced as far as four feet apart, tend to be better suited for skylights because they leave enough room to cut and fit a skylight between the rafters.
- Truss-framed roofs, named for the prefabricated triangular units they’re made of, are less ideal. Trusses aren’t designed to be cut after installation; doing so can compromise the structural integrity of the roof.
Even if your installer is willing to add a skylight to a truss-framed roof, you may be forced to go with smaller skylights no more than two feet wide to fit the limited space available between the beams that make up each truss. This may not be wide enough for your needs, given that the recommended size for a skylight is between five and 10 percent of the square footage of the room it’s lighting.
A stick-framed roof is not an automatic green-light to the project, though; the slope of the roof could still pose a challenge. Gable, hip, and shed roof shapes are ideal because all have a slope that will divert rainwater and debris downward off the skylight. Otherwise, left standing for a bit of time, collected rainwater could stain the glazing. Flat roofs are poor choices for skylights just for this reason.
2. Glass isn’t the only option for glazing.
Skylights consist of a wood, vinyl, or metal frame that holds a light-transmitting piece called glazing. You’ll have your pick of either plastic or glass skylight glazing.
Glass glazing—which is twice as heavy and anywhere from 25 percent to five times more expensive than plastic—is your best bet. It’s the clearer and more scratch- and impact-resistant option, plus it resists discoloration, blocks out more UV rays, and comes in custom sizes and shapes. Unlike plastic, glass glazing also affords two insulating options:
- a low-emissivity (low-E) coating, which is an invisible layer of metal oxide on the inner glass pane
- an intervening layer of argon gas between the two panes to help retain indoor heat in winter, stave off exterior heat in the summer, and block out nearly all UV rays
If you choose glass glazing, be sure to select tempered or laminated glass to prevent it from breaking into sharp pieces on impact. The most durable glazing is double-paned—consisting of either two panes of tempered or laminated glass or an outer pane of tempered glass over an inner pane of laminated glass.
Plastic glazing, sold in a stronger polycarbonate or weaker acrylic variety, is cheaper, half as light, and less likely to break than glass. But it also scratches and becomes discolored more easily, blocks little to no UV light, and is usually only sold in standard sizes and shapes such as flat, pyramidal, arched, or domed.
3. Protective glazing films or coverings regulate light and temperature levels and add privacy.
The addition of an overhead window can mean lots of light and less privacy. That said, you can dial down the brightness, glare, and heat in a room—even regain privacy—by tinting the glazing with colored window film or installing a shade below the inner pane of a skylight’s glazing. Tinting windows creates a more softly-lit, ambient indoor setting and can additionally help a skylight block out UV light if it has plastic glazing or glass that isn’t low-E. But it substantially reduces the percentage of visible light your skylight transmits, and because window film on a skylight is impractical to remove because of its height, if removable at all, you’ll be committing to a lower level of natural lighting in the room year-round.
Skylight shades, which come in motorized remote-controlled varieties or manually operated varieties that can be drawn open or closed with a chord, help your skylight transmit the maximum amount of visible light when open or dim and cool the room when partially or fully closed.
4. Some skylights let in air and light.
Skylights come in fixed varieties that always remain closed and vented varieties you can open or close at your discretion. Because fixed skylights transmit only light and are designed to keep in heat and keep out moisture, they’re generally more energy-efficient and less prone to leaks. But they don’t promote air circulation, which makes them a better option for rooms that are already well-ventilated. Vented skylights, which include manually operated varieties you can open or close with a hand crank or motorized options you can control with a remote, increase the risk of leaks and heat loss or build-up. But they let in both fresh air and natural light, which makes them particularly useful in stuffy rooms like attics.
5. Location matters.
When scouting out a skylight location, settle on the specific room you want to light. It should ideally be one directly below the roof—for example, a dark finished attic or a guest bedroom. Your installer will then hone in on a section of the roof above that room that meets the minimum slope requirements in the manufacturer’s specs for your skylight. (Generally, you want to install a skylight at a slope of five to 15 degrees higher than your latitude.)
The direction of the skylight is equally important. North-facing skylights are ideal, as they supply continuous year-round illumination. Avoid positioning skylights where your view would be blocked by the walls of a taller nearby building or other obstructions. Large trees in the vicinity of a skylight may only be desirable for homeowners in hot climates who need more shade.
6. Leave skylight installation to the pros.
The availability of skylights with flashing included (metal strips used to weatherproof the skylight) make it possible for DIYers with carpentry and roofing experience to tackle a skylight installation for a lower cost of between $150 to $500. But for the average DIYer, the complexity of installation and the risks of falling or causing a roof leak make professional installation well worth the higher cost of $650 to $3,500. Installing a skylight involves removing roof shingles, cutting a hole into the roof, modifying the framing to fit the skylight, installing the flashing and skylight, and patching up parts of the roof and ceiling above and below the skylight.
A skylight installation in an existing roof requires re-shingling certain sections of your roof, so hold off on starting this project until you need your roof replaced. Additionally, wait for a clear day to start this project—you don’t want rain slipping you up on the roof or seeping through the roof opening and into your home.
7. Keep your skylight clean and clear with regular maintenance.
Use these tips to keep your skylight sparkling year-round:
- Inspect ceilings and floors in rooms with skylights biweekly for leaks. Damp spots on the ceiling or carpet—especially after heavy rain- or snowfall—can indicate a leak in the skylight that can give way to mold if not repaired.
- Dust skylights monthly using a telescoping dust mop.
- Deep-clean skylights annually. Use a sponge mop saturated in soapy water to gently scrub down the inner pane of the skylight, and use a telescoping power washer to eliminate dirt and grime on the outer pane.
- Have skylights inspected by a professional annually for hairline cracks and other flaws that can lead to more extensive structural damage down the line. If you’re uncomfortable cleaning skylights yourself, have your skylights professionally cleaned at the same time you have them inspected.
- If replacing your roof and installing a new skylight at the same time, ask your roofer to have an ice and water shield installed with the roof underlayment to anticipate ice dams. Having a skylight makes your roof more prone to forming ice dams (melted snow that has refrozen) around the outer edges of the skylight, which can prevent rainwater runoff or melt and create a leak if they seep through the roof shingles.
- Clear fallen snow from the roof with a shovel or rake before it freezes to prevent the formation of ice dams. If the snow melts and freezes into ice, you’ll need to use a mallet to break it into small chunks that will fall off the roof themselves. Or place calcium chloride-filled socks on the ice to melt it. You can also call a roofer to steam away the ice dams on your roof.