Windows · Service

Foggy windows are a glass problem, not a window problem

When the sealed unit can be swapped in a frame that is still perfectly good, when it cannot, and why the company advertising to you is not the trade that does it.

Get matched free All windows services

In short

What is window glass replacement?

Window glass replacement means swapping the glass — usually an insulated glass unit, two or three panes bonded to a spacer and sealed at the edge — while leaving the frame, sash and hardware in place. It is the right answer to fogged, misted or broken glass in a window that otherwise works. Seal failure typically shows up long before a frame reaches the end of its life, which is exactly why replacing the whole window at that point is so often the more expensive answer to a smaller problem.

Triggers

Signs you need window glass replacement

Haze, mist or visible droplets between the panes that you cannot wipe off from either side — the definitive sign of a failed edge seal
A permanent cloudy film or mineral streaking between the panes, which is what the fogging leaves behind once it has cycled for a few seasons
A cracked or shattered pane in a frame that is straight, sound and still operates
One pane feels noticeably colder than the others, or the glass has visibly bowed — signs the gas fill has gone
A scratched or etched pane, often from pressure washing or a builder’s cleanup
You want to upgrade one or two problem windows to low-E or laminated glass without touching the frames

Seeing something not on this list? Browse windows problems by symptom →

The job

How window glass replacement actually works

Confirm it is the glass and not the window

Fogging between the panes is a sealed unit failure and nothing else. Condensation on the room side of the glass is a humidity issue in your house; condensation on the outside face on a cool morning is usually a sign the glass is performing well.

Watch for: A diagnosis that jumps straight from "fogged" to "your windows are done". The frame and hardware are separate components with separate lifespans, and they are usually the longer-lived ones.
Identify the unit and check it is field-replaceable

The glass shop needs the manufacturer, the sash construction and the glazing method. Many units are held in with removable glazing beads or a wet-glazed stop that can be cut out. Some — particularly certain newer vinyl and clad sashes — are glazed into the sash at the factory and are not intended to be opened up on site.

Watch for: Nobody checking before quoting. If the sash is not field-glazable, the honest options are a replacement sash from the manufacturer or a replacement window, and finding that out after a deposit is a bad day.
Measure and specify the replacement

The new unit is made to the measured sight size and pocket depth, and specified to match: pane count, overall thickness, spacer type, gas fill, low-E coating and coating surface, and any tempered or laminated requirement.

Watch for: A quote for "double pane glass" with no low-E specified on a window that had it. You will not see the difference on day one; you will feel it, and the mismatched pane will look different from the ones beside it.
Safety glazing where code requires it

Codes require tempered or laminated glass in specific hazardous locations — near doors, close to the floor, in and around wet areas, and at stairs and landings. If the original pane was tempered, its replacement has to be too.

Watch for: A quote that replaces a tempered pane with annealed glass because it is cheaper. Look for the small permanent etched stamp in a corner of the existing pane; if it is there, the replacement needs one too.
Fabrication lead time and fitting

Sealed units are made to order, so expect a wait between measure and fit. The fitting itself is usually under an hour per opening: beads or stops come off, the old unit comes out, the new one is bedded and the stops go back.

Watch for: A sash taken away and returned with a unit that rattles or is bedded dry. The unit should be set on setting blocks and sealed to the sash, not just wedged with the beads.

Money

What does window glass replacement cost?

Replacing a sealed glass unit is typically a small fraction of what a whole replacement window costs, which is the entire economic point of doing it. The spread comes from pane size, low-E and gas specification, and whether tempered or laminated glass is required. Figures by glass type are in the cost guide.

See the full window glass replacement cost guide — by material, size and region →

Straight answer

When window glass replacement is the wrong call

Everyone else ranking for this is paid when you say yes. Here's when you shouldn't.

The frame is rotten, racked or the hardware is dead. New glass in a failing frame is money spent on the one part that had not failed. If two of the three components are gone, replace the window.
Several windows have failed at once and they are all the same age. Seal failures arriving together usually mean the whole batch is at the end of its service life. One or two units is a repair; ten is a pattern, and the economics shift.
The sash is factory-glazed and not field-replaceable. On some newer vinyl and clad units the glass is not designed to come out. A manufacturer sash replacement may still beat a full window, but glass-only is off the table and anyone promising it has not looked.
The window is discontinued and no matching unit can be sourced. Unusual thicknesses, obsolete spacer systems and decorative or divided-light glass all run into this. The honest answer is sometimes that the part does not exist.
You were going to replace those windows this year anyway. A sealed unit is not a stopgap purchase you get value out of in six months. If replacement is already funded and scheduled, live with the haze.
The glass keeps breaking in the same opening. Repeated breakage in one place is a symptom — thermal stress from a partially shaded pane, movement in the structure, or an impact source you have not identified. Replacing the glass again without finding it is a subscription.

Before you sign

What to check when hiring for window glass replacement

Are you a glass company, or a window replacement company?

The most useful question on this page. Glass shops are a separate trade with separate listings, and they are the ones who quote a sealed unit swap. A replacement-window company usually will not — not out of dishonesty, but because it is not what they sell.
Is my sash field-glazable? Have you looked?

This determines whether the job is possible at all. It takes one look at the glazing beads or stops to answer, and it should be answered before any deposit changes hands.
Will the new unit match the low-E coating, gas fill and pane count of the original?

Otherwise you get a pane that performs and even looks slightly different from the ones either side of it. Ask for the specification in writing, including which surface the coating is on.
Does this location require tempered or laminated glass?

Near doors, low to the floor, by stairs, around tubs and showers. Check the existing pane for an etched safety stamp in the corner and say so when you call — it changes both the price and the legality.
What is the lead time, and what happens to the opening in the meantime?

Sealed units are made to order. For a broken pane, ask about a temporary board-up or a single-pane holdover, and whether that is included or extra.
What warranty comes with the sealed unit, and does it cover seal failure?

Sealed unit warranties against seal failure are common and are the whole point of the purchase. Get the term in writing on the invoice and note whether it is transferable if you sell.

All windows hiring checklists →

Local pros

Window Glass Replacement near you

Local pro matching for window glass replacement is rolling out by metro. Enter your ZIP and we'll match you with vetted pros in your area today.

Related work

Often done at the same time

Window Repair

Sashes, balances, cranks and frames

Window Replacement

When the whole unit really is done

Window Installation

Fitting and flashing a new unit

All windows services →

Go deeper

Guides & terms

Guides

Windows guides — energy ratings and glass specification

All windows guides →

Terms on this page

Low-E, gas fill and U-factor, defined

Full windows glossary →

FAQ

Window Glass Replacement — questions people ask

Still have a question? Talk to our team →

Can foggy windows be fixed without replacing the whole window?

Usually yes. Fogging means the edge seal on the insulated glass unit has failed and moisture is getting between the panes. If the frame, sash and hardware are sound, the unit is field-replaceable and a matching one can be made, swapping the glass is straightforward and costs a fraction of a new window. The frame typically has years of life left at the point the seal goes.

Why did my window company tell me the whole window has to go?

Because that is what they sell. The trade that does sealed unit replacement is the glass business, and most homeowners do not realise it is a separate industry with separate local listings. This is not a conspiracy — a replacement-window company has no glazing van, no supplier account for one-off units, and no reason to route you elsewhere. It does mean you should get a second opinion from a glass shop before accepting that a foggy window is a dead window.

Is there a way to defog a sealed unit instead of replacing it?

There are services that drill the unit, clean or dry the cavity and fit vents. Opinions in the trade are genuinely divided: it can clear the appearance, but the unit is no longer a sealed insulating unit afterwards, so the gas fill and part of the thermal performance are gone for good. Treat it as a cosmetic fix on a window you do not intend to keep, not as a repair.

How long does it take to get replacement glass?

The unit is manufactured to your measurements, so a wait of a couple of weeks is common and can be longer for tempered, laminated or unusual sizes. The fitting itself is typically under an hour per opening. For a broken pane, ask about a temporary board-up while you wait.

Does insurance cover broken window glass?

Sudden accidental damage — storm, impact, vandalism — is commonly covered, but a single pane frequently costs less than the deductible, so a claim may not be worth filing. Seal failure is wear and is not covered by any homeowners policy. Photograph the damage and the cause before anything is cleared away if you intend to claim.