A skylight can transform a dark room with natural light, but it is important to understand that installing one is a roofing project, not a window swap. You are cutting a hole in the roof and then keeping water out of it for decades, which makes flashing and installation quality everything. This guide explains the main skylight types, how they are installed, and why the details decide whether a skylight is a joy or a source of leaks.
The short version
Skylights come as fixed (non-opening) or vented (opening) units.
Curb-mount sits on a built-up frame; deck-mount attaches closer to the roof.
Flashing is the single most important detail for keeping water out.
Tubular skylights are a smaller, easier option for tight spaces.
Install a new skylight when you reroof to integrate flashing cleanly.
Fixed vs. vented
The first choice is whether the skylight opens. A fixed skylight is sealed and does not open; it is simpler, less expensive, and has fewer parts that could leak, making it a good choice purely for light. A vented skylight opens to let hot air and humidity escape, which is valuable over kitchens and bathrooms; it may be operated manually or by a motor and can include rain sensors that close it automatically. Vented units cost more and have more components, but the ventilation can be worth it in the right room.
Curb-mount vs. deck-mount
How the skylight attaches to the roof is the next distinction. A curb-mount skylight sits on a raised frame, or curb, built up from the roof surface, which lifts it above the roofline and can simplify certain installations and replacements. A deck-mount skylight attaches lower and closer to the roof deck for a sleeker, lower profile. Both can perform well; the right choice depends on the roof, the product, and the look you want. Your roofer can advise which suits your situation.
Tubular skylights
For smaller spaces like closets, hallways, and bathrooms, a tubular skylight is a compact alternative. A small dome on the roof captures light and channels it down a reflective tube to a diffuser in the ceiling. Tubular units bring in surprising brightness, are less expensive and less invasive than a full skylight, and are easier to fit where a large opening is not practical. They do not offer a view of the sky, but for pure daylight in a small room they are efficient.
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Why flashing makes or breaks it
Every skylight is a penetration in the roof, and every roof penetration is a potential leak point. What keeps a skylight watertight is the flashing — the layered metal and membrane that channels water around and away from the unit. Manufacturers supply flashing kits matched to their skylights and roofing type, and installing that flashing correctly, integrated with the shingles and underlayment, is where skill matters most. The overwhelming majority of skylight leaks come from flashing that was installed poorly, not from the skylight glass itself.
Choice
Best for
Fixed skylight
Pure daylight where ventilation is not needed
Vented skylight
Kitchens, baths, and rooms that trap heat or humidity
Tubular skylight
Small rooms, closets, and hallways
Pro tip — add or replace skylights when you reroof
The cleanest time to install or replace a skylight is during a roof replacement, when the shingles and underlayment are already open and new flashing can be woven in properly. Retrofitting a skylight into an existing roof is possible but requires carefully disturbing and resealing the surrounding roofing. If a reroof is on the horizon, plan skylight work to coincide with it.
Planning your installation
Beyond type and mounting, think about placement for the light you want, the room below, and the roof structure — cutting the opening may involve framing considerations best left to a professional. Consider glass options that manage heat and glare, and factor in the interior finishing of the light shaft. Because the stakes for watertightness are high, hire a roofer or installer experienced specifically with skylights and their flashing systems. A well-installed skylight can last many years; a poorly flashed one becomes a recurring headache.
Thinking about a skylight?
Find licensed local roofers experienced with skylights on Roofers At Your Service.
No. A quality skylight installed with proper flashing by an experienced installer can stay watertight for many years. Leaks are usually the result of poor flashing or installation, not an inevitability of having a skylight.
Should I get a fixed or vented skylight?
Choose fixed if you only want light and prefer fewer parts and lower cost. Choose vented for rooms that trap heat or humidity, like kitchens and bathrooms, where being able to open it adds real value.
Can a skylight be added to an existing roof?
Yes, though it requires carefully cutting into and resealing the roof and possibly adjusting framing. It is often cleanest to do during a reroof so flashing integrates with new roofing. An experienced installer can retrofit one properly if needed.
Who should install a skylight?
A roofer or installer experienced specifically with skylights and their flashing systems. Because the main risk is water intrusion at the roof penetration, flashing expertise matters more than general handyman skill.
General information for homeowners — not professional advice. Roofing costs, materials, codes, and insurance rules vary by location and change over time; confirm with a licensed local roofer.
