Replace window glass only
Replace the glass or the whole window?
You do not always need a new window. Sometimes a new sealed unit in a sound frame is enough. Here is how to tell the difference — and how each choice is quoted.
When one window fails, the instinct is often to replace the lot. But a modern double-glazed window is made of two separate parts — the frame that sits in the wall, and the sealed glass unit that clips into it. Either can fail independently. Knowing which has gone wrong is the key to a sensible quote, because replacing only the glass costs far less than replacing the whole window.
When the glass alone is the problem
If your frames still open and close smoothly, seal tightly and show no rot or cracking, but the glass has misted, cracked or lost its energy performance, a new sealed unit is usually all you need. The most common case is condensation trapped between the panes — a sign the unit’s edge seal has failed. That is a glass problem, not a frame problem. Our guide on misted double glazing replacement covers this in detail.
Glass-only swaps are quicker, cheaper and less disruptive, and they let you keep frames that are otherwise in good order. A fitter removes the failed unit and installs a new one of the same size and specification, sometimes upgrading to a warmer or acoustic glass at the same time.
When the whole window needs replacing
Some faults live in the frame. Rotten or swollen timber, cracked or discoloured uPVC, failed hinges and locks, draughts that no adjustment fixes, or single glazing you want to upgrade all point to a full replacement. Once a frame is past its best, patching the glass is a false economy — you will be back to the draughts and the maintenance within a year or two. A whole-window replacement also lets you improve the energy rating, security and appearance in one go.
Still weighing it up? This independent-style guide on repair or replace — how to decide is a useful sanity check, and if you want to match new units to the rest of the house, compare window styles to replace like-for-like.
How each option is quoted
Glass-only work is priced per unit by size and glass specification. A full window replacement is priced by frame style, opening arrangement and glass, as our quotes by window type hub explains. A good surveyor will tell you honestly which you need rather than upselling — and where a mix makes sense (new glass here, new windows there), the quote should itemise both.
Get an honest assessment
The only reliable way to know is a home assessment, where a surveyor checks the frame and the seal. Prices vary by region and specification, so treat any single number as a starting point. You can get a fast quote direct, no showroom, or browse the current double glazing deals and prices for context. Funding and contribution options may be available subject to eligibility and a home survey, and £0-upfront options may be available for those who qualify. The quote and assessment are free and no-obligation.
Not sure which you need? Get a quote
Tell us what has failed and your postcode and we will match you with vetted installers for a free, no-obligation assessment.