When a skylight starts leaking, resealing is the first thing anyone suggests. It is quick, it costs a fraction of a replacement, and there is no unit to wait on. Sometimes it is exactly the right repair. Other times it is a season of quiet followed by the same stain on the ceiling, because the seal that failed was never one you can get at from the roof.
The short version: if the water is getting in around the skylight, resealing fixes it. If the water is getting in through the skylight, resealing does nothing. Those are two different seals, and telling them apart is the whole job.
Every glass skylight on a New York roof has at least two seals doing completely different jobs.
The perimeter seal is everything where the skylight meets the roof. Sealant at the curb line, the flashing kit and its laps, the counterflashing, the fasteners. This seal lives outside in the sun and it is meant to be maintained. It dries, it shrinks, it opens up, and it can be renewed. When we talk about resealing a skylight, this is what we mean.
The glass seal is the factory edge seal buried inside an insulated glass unit, holding the two panes together with the gas between them. It is sealed in a plant and it cannot be opened, repaired or renewed on your roof. Fog between the panes, haze that will not wipe off, or a puddle sitting inside the glass all mean this seal has gone. No work on the outside of the unit will bring it back. That case is covered on our page on skylight glass replacement.
These are the jobs where we quote a reseal without hesitation, because the unit is sound and the failure is on the outside of it.
| What we find | Why a reseal solves it |
|---|---|
| Dried, cracked sealant at the curb line | The bead has done its service life. Cut it out, prep the substrate, lay a fresh bed with a proper roofing grade sealant and the water path is closed. |
| Open or lifted flashing laps | Wind and thermal movement work the laps apart. They can be reset and sealed without touching the skylight. |
| Fasteners backed out and weeping | Each one is a small hole in the roof. They get reset and sealed individually. |
| Sound glass, sound curb, stain on the ceiling | The unit has life left. Spending on a replacement here is spending on the wrong thing. |
| Commercial dome with a good curb | Resealing the flange, and replacing only the dome if it has crazed, keeps the curb and the roof membrane undisturbed. |
On a job like this the scope is honest and narrow. We prepare the perimeter, apply the sealant to the curb and flange, dress the laps, and water test it before we leave.
We turn down reseal work regularly, and this is why. A seal only holds if what it is stuck to is sound.
The insulated glass unit has failed. Fog, haze or standing water inside the glass. The leak you are chasing may not even be a roof leak. Resealing the outside of a dead unit leaves you with a dead unit and a bill.
The curb has gone soft. If the wood under the flashing is spongy, nothing will bond to it and nothing will stay bonded. The curb gets rebuilt first. There is no sealant that fixes rot.
Somebody already coated it. The most common thing we are called to undo is a skylight flooded with black roof coating or tar by a roofer who was there for something else. It buys a quiet season, traps water against the frame, and has to be cut away before any real repair can start.
The acrylic is crazed or cracked. On domes the damage is through the material, not on the surface. The curb and flange can be resealed. The dome has to be replaced. See acrylic dome skylights.
The unit is out of production and already leaking at the frame. At that point a reseal is a delay, not a repair, and the delay has a cost of its own in ceiling and plaster.
If you are not sure which of these you have, our skylight diagnostic walks the symptoms, and why a skylight keeps leaking after it was repaired covers the case where somebody has already tried.
| Reseal | Replace | |
|---|---|---|
| Fixes | Water getting in around the unit | A unit that has failed, or a curb that has |
| Unit order | None. Material is on the truck | The skylight comes from the factory, so there is a lead time |
| Time on site | Usually a single visit | A full day, more on a hoist or a cut through |
| Interior work | None in most cases | Sometimes, depending on the shaft |
| What it does not do | Nothing for fogged glass or a soft curb | Nothing you need if the unit was fine |
| Warranty | Our labor warranty on the work performed | Our labor warranty plus the manufacturer warranty on the new unit |
Published figures for replacement work, including the installed price on a sound curb, are on our pricing page. Resealing is quoted off what we find on the roof, because the scope depends entirely on the condition of the perimeter. We do not publish a reseal number we would then have to walk back once we have seen it.
Someone who installs skylights every day comes out and looks at the roof. Not a salesman with a tablet.
We read the data plate so we know what unit you actually have and whether parts and glass are still available for it. We check the glass for a failed edge seal. We press the curb for soft spots. We look at the flashing laps, the counterflashing and the fasteners. We look at what the last person to work on that roof did, because that is often the whole story.
Then you get a straight answer and a written scope. If a reseal fixes it, that is what we quote. If it does not, we tell you that instead of selling you one. The assessment is free and there is no charge for the opinion either way.
We have been doing skylights in the five boroughs since 2005 and skylights are all we do. Home improvement license 2084179, fully licensed and insured, VELUX trained and approved.
We will come out, read the unit, press the curb and tell you which one it is. Free, and in writing.
Yes, when the water is getting in around the outside of the unit. A failed perimeter seal, open flashing laps or a dried out bed of sealant at the curb line are all things a reseal fixes properly. If the water is coming from inside the glass itself, or the curb underneath has gone soft, resealing the outside will not stop it.
They are two different seals and they fail for different reasons. The perimeter seal is the sealant and flashing where the skylight meets the roof. It is exposed to sun and weather and it is meant to be maintained. The glass seal is the factory edge seal inside an insulated glass unit that holds the two panes together. That one is sealed at the factory and cannot be repaired in place. Fogging or water between the panes means the glass seal has gone, and no amount of resealing outside will change it.
A properly prepared reseal on sound substrate gives you years, not months. The variables are what is underneath and how much sun the roof takes. We will tell you at the assessment whether the surface will hold a seal or whether you are buying a short reprieve.
Much cheaper, and that is exactly why it gets oversold. A reseal is labor and material on a single visit with no unit to order. A replacement is a new unit, new flashing and a longer day. We quote the reseal only when it is the repair that actually solves the problem, because a reseal on a dead unit is money spent twice.
No. Flooding a skylight curb with roof coating or tar is the single most common thing we are called in to undo. It hides the leak for a season, it traps water against the frame, and it has to be cut off before anything can be done correctly. If a skylight on your roof is buried in black mastic, the reseal conversation starts with removing it.
The curb and flange can be resealed. The dome itself cannot be repaired once it has crazed, yellowed or cracked, because the damage is through the material. On a commercial roof with a sound curb, resealing the flange and replacing just the dome is often the right scope.
Yes. Most of the resealing we do is on units somebody else put in, often years ago. We will tell you who made it and what condition it is in before we quote anything.
Faster than a replacement, because there is no unit to order. A reseal is scheduled off our repair calendar once we have seen the roof. A replacement waits on the skylight itself coming from the factory.
Resealing and perimeter repair across Brooklyn, Manhattan, Queens, the Bronx, Staten Island, Long Island and Westchester. For leak work generally, start at skylight leak repair. For commercial roofs and dome work, see commercial skylights.