Why a roofer should install your skylight
A skylight is a hole in your roof. Whether it stays dry depends almost entirely on how the opening is framed and how the flashing is integrated with the roofing around it. Most skylight leaks we see come from installation and flashing problems, not from the skylight itself. As roofers, we install skylights as part of the roof system, using the manufacturer's flashing kit woven into the shingles or membrane.
- Framed opening: headers carry the roof load around the cut rafters.
- Ice-and-water collar: self-adhered membrane sealed to the deck and up the curb, under all metal flashing.
- Head flashing on the uphill side tucks under the shingles above.
- Apron (sill) flashing on the downhill side lies over the shingles below, so water always flows onto the next layer down.
- Insulated, low-E glazing limits heat gain and condensation.
- Light shaft carries daylight to the room below.
Step flashing on the sides of the skylight, woven course by course with the shingles, is not visible in this section.
Skylight options
- Fixed skylights: daylight only, for stairwells, hallways and high ceilings
- Venting skylights: manual, electric or solar-powered openers. Useful in bathrooms and kitchens to release heat and moisture. Some models have rain sensors that close them automatically.
- Tubular skylights (sun tunnels): a small roof opening and a reflective tube that bring daylight to interior rooms and closets without major framing
- Blinds and glazing: light-filtering or blackout blinds, and low-E glass to limit heat gain
Our installation process
- Site the skylight around rafters and the room below, checking sun exposure
- Cut the opening and frame headers to carry the roof load
- Install the unit, ice-and-water membrane collar and the manufacturer's flashing kit
- Re-shingle or re-membrane around the unit
- Build out the interior light shaft (drywall finishing can be included or left to your contractor)
The best time to add a skylight is during a roof replacement or new roof installation, when the flashing integrates with all-new roofing. Replacing an existing unit? See skylight replacement.
Permits and historic districts
Montgomery County's homeowner permit guide lists roof coverings among work that most likely does not need a permit, but it does not list skylights. Cutting a new opening changes roof framing, so we confirm permit requirements with the Department of Permitting Services or your municipality before work begins. In the Chevy Chase Village Historic District and other historic areas, new skylights visible from the street are reviewed by the Historic Preservation Commission.
Daylight under a heavy canopy, and heat control in summer
There is a specific local reason skylights are so popular in this area: the same mature tree canopy that keeps Bethesda and Chevy Chase streets shaded keeps the interiors of their houses dark. Center-hall colonials and foursquares have deep floor plans where interior stairs, hallways and renovated bathrooms are far from any window, north-facing rooms get no direct sun at all, and mid-century homes in North Bethesda often have long low rooflines over rooms with few openings. In those houses a skylight or a tubular sun tunnel is frequently the only way to get real daylight into the middle of the plan without altering the exterior in a way an HOA or a historic district would question.
Our climate then drives the glazing choices. In humid summers with high sun angles, a unit with a low solar-heat-gain coating, or a factory blind or solar shade, is the difference between a bright room and an unusable one; this matters most on south and west-facing slopes. In winter the issue reverses: a warm-edge insulated glass unit, plus a shaft that is genuinely insulated and air-sealed where it passes through the attic, is what keeps humid indoor air from condensing on the cold perimeter of the glass and dripping. Condensation mistaken for a leak is one of the most common skylight complaints we are called about, and the fix is usually in the shaft and the attic rather than on the roof, which is why we look at both before quoting roof repair.
Installation quality comes down to the curb height and the flashing kit rather than the brand on the glass. A deck-mounted unit on a steep slope with a kit matched to the actual pitch is a durable assembly; the same unit set too low on a porch or addition roof with a shallow pitch will leak in wind-driven rain no matter how much sealant it gets, so on low-slope surfaces units are curb-mounted well above the membrane as part of flat roof installation. Because the flashing weaves into the surrounding roof courses, the most economical time to add a skylight is during a roof replacement. If your existing units are hazed, cracked or leaking rather than simply missing, the right project is skylight replacement.
Skylight Installation across Bethesda, North Bethesda and Chevy Chase
We provide skylight installation throughout southern Montgomery County, including Bethesda, MD (20814, 20816, 20817) , North Bethesda, MD (20852) , and Chevy Chase, MD (20815) . Each area page covers the housing types, permit considerations and storm history particular to that community.
Frequently asked questions
Do skylights always leak eventually?
No. Skylights installed with the manufacturer’s flashing kit and integrated properly with the roofing perform well. Leaks usually come from improper flashing, old sealant-only installs, or condensation that is mistaken for a leak.
Can a skylight go in a flat roof?
Yes, with a curb-mounted skylight on a raised curb that is flashed into the membrane. See flat roof installation for related details.