It is the question we are asked more than any other. The glass has gone cloudy, or there is water sitting between the two panes, or a branch cracked it, and replacing one piece of glass sounds a great deal cheaper than replacing the whole skylight. Sometimes it is the right call. On most residential units in New York it is not, and the reason has nothing to do with what we would rather sell you.
One photo answers this faster than any phone call. There is a data plate on the inside of the frame, usually on the side you can reach from a ladder. Photograph it and send it in. That plate carries the make, the model and the year, and those three things decide whether a replacement pane exists for your unit at all.
On a modern residential skylight the glass is not a pane sitting in a frame. It is a sealed insulated glass unit, two or three sheets of glass with a spacer and an inert gas between them, and on most units it is bonded into the sash at the factory. There is no gasket to pull out and no bead to unscrew. Taking the glass out means destroying the seal that makes the unit weathertight, and whatever goes back in is held by site applied sealant rather than a factory bond.
That is why the manufacturers themselves mostly do not sell a replacement pane for these units. Where a pane is available, it is normally for the larger fixed and commercial products, not for the deck mounted and curb mounted units on an ordinary house. Our pricing page says full unit replacement only for exactly this reason.
So the honest sequence is: find out what the unit is, find out whether a pane exists for it, and only then talk about price. Anyone who quotes you a glass swap before they know the model is quoting a job they have not looked up.
If you are looking at cloudiness, a milky film, or droplets that appear on a warm day and vanish on a cold one, and wiping both sides changes nothing, the moisture is inside the sealed unit. The perimeter seal has failed and the gas fill has gone with it. That is the single most common reason people ask us about glass.
It matters because a failed seal is a clock, not an event. The unit is not leaking into your house and it is not dangerous. What it has lost is its insulating value, so that skylight is now a cold spot in winter and a hot one in summer, and the haze gets worse every season as more moisture cycles in and deposits on the inner surfaces.
It also tells you something about the rest of the unit. Seals do not usually fail early. If the seal has gone on a unit that has been up there twenty years, the gaskets around the sash, the cladding on the frame and the flashing in the roof are the same age and have had the same weather. Replacing the glass in that frame is putting a new part into an assembly where everything else is at the end of its life.
Nearly every unit made in the last thirty years carries a plate or a printed label on the inside face of the frame. On VELUX units it is usually on the side of the sash and you can read it from inside the room with a ladder and a torch. It gives the product code, the size code and the year of manufacture.
From that we can tell you three things in one phone call. Whether the manufacturer still makes a glazing unit for that product. Whether the product is still current, which decides whether a new unit will drop straight into your existing curb or opening. And how old it actually is, which is usually a few years older than people think.
If you cannot get to the plate safely, do not go on the roof for it. Photograph the skylight from inside the room with the whole frame in shot, and the ceiling around it, and we will narrow it down from the profile. Our skylight diagnostic walks through the same questions and tells you which four photos get an answer fastest.
There are real cases, and we do them. A large fixed commercial unit, a steel framed pyramid or a ridge system where the frame is structural and the glazing sits in a captured system with pressure plates and gaskets is designed to be reglazed. The frame outlasts several sets of glass and swapping a pane is ordinary maintenance.
Wire glass in an old steel frame over a stair bulkhead is its own case, and we have a page on wire glass replacement that covers what is allowed to go back in and why the answer is often a laminated inboard lite rather than more wire glass.
A site built laylight or a leaded panel under a roof skylight is glazing in a frame a joiner made, not a sealed unit, and that is repaired as glazing. And a cracked outer pane on a unit only a few years old, where the seal is still intact and the manufacturer lists the pane, is worth doing.
What these have in common is that the frame is sound and separately serviceable. That is the test. Not the size of the glass and not the size of the bill.
A straightforward full unit replacement on a sound existing curb starts at $2,079 installed, which is the unit plus our standard replacement labor of $1,600. That figure assumes the curb underneath is in good condition and the opening does not change.
Cutting a new opening where there was none is a different job and starts at $3,500 installed, because it includes framing the opening, flashing it into the roof and finishing the shaft inside.
Those are starting points, not quotes. What moves the number is the unit type you choose, whether the unit vents, whether the curb needs rebuilding, how the roof is reached, and how many units are being done at once. Several units in one visit is meaningfully cheaper per unit than the same units done one at a time, because the roof protection, the interior protection and the mobilization are shared. The Skylight Finder prices the common configurations on the spot.
The comparison worth making is not glass against unit. It is glass against unit over the next fifteen years. A glazing swap into a twenty year old frame leaves you with the original flashing, the original gaskets and the original curb, and the next thing to fail will cost another visit.
Most skylight leaks in New York are not glass failures at all. They are curb failures and flashing failures. On a flat roof the unit sits on a built curb, and if that curb has gone soft at the top, or the roof was recoated over the base flashing, water gets in regardless of what is glazed above it.
This is why we look at the curb before we talk about the unit. If the curb needs rebuilding, that is the real job and the glass question becomes academic. If the curb is sound, a new unit drops onto it and the flashing is renewed as part of the install.
It is also why a roofer who photographs your skylight from the roof will almost always say replace the whole thing. From up there the only visible evidence is the outside of the unit and the condition of the roof around it. The data plate, the inside of the frame and the shaft are all things you can only assess from inside, and those are what decide whether the frame is worth keeping.
We come and look, and there is no charge for it. The person who looks at it is the person who tells you what failed, and we do not send a salesman.
We read the data plate, check whether a glazing unit is available for that product, look at the condition of the frame, the gaskets and the cladding, and get into the shaft to see what the ceiling and the plaster are telling us. Then we tell you which of the two it is and why, with the reasoning, not just the number.
If the answer is that a pane exists and the frame is worth keeping, we will say so and quote the glass. If the answer is that it is a new unit, we will show you what we saw. We would rather lose a glazing job than sell you one that fogs again in three winters. More of our work on this is in the gallery, and skylight repair covers the other failure modes.
The perimeter seal of the sealed glass unit has failed and the gas fill has escaped, so humid air is cycling in and condensing on the inner surfaces. It is not a leak into your house and it is not urgent, but the skylight has lost its insulating value and the haze gets worse each season. It cannot be dried out or resealed in place.
No. The deposit is on the inside faces of a sealed unit, so no amount of cleaning reaches it. Drilling and venting services exist, but they turn a sealed insulated unit into a vented single cavity, which gives up the insulation value permanently and does not restore clarity. We do not do it.
Look on the inside face of the frame, usually on the side of the sash where you can reach it from a ladder inside the room. There is a plate or printed label with a product code, a size code and a year. Photograph it and send it to us. Do not climb on the roof to look for it.
Only where a replacement pane is actually made for your product and the frame is sound and separately glazed, which is the case on large fixed and commercial units more often than on ordinary residential ones. On a typical house skylight the glass is factory bonded into the sash, so a glass only swap is not offered and a full unit replacement starting at $2,079 installed is the real comparison.
He may well be right, but from the roof he can only see the outside of the unit and the roof around it. Whether the frame is worth keeping is decided by the data plate, the condition of the frame and gaskets, and the state of the shaft, and all three are assessed from inside. Get it looked at from indoors before you decide.
If the unit is recent, the seal is still intact and the manufacturer lists a glazing unit for that product, yes, and that is worth doing. Send us the data plate and we will check availability. If the inner pane is cracked too, or the unit is already fogged, the sealed unit has been compromised and the pane swap is not the fix.
Overhead glazing generally needs a laminated inboard lite so that nothing can fall into the space below if it breaks, and on an older steel framed or wire glass unit over a stair or a common area the rules are stricter than on a house. If the skylight is over a common element, the work usually also needs board approval and a certificate of insurance, which is covered on our co-op and condo boards page.