Casement window replacement surveyed and fitted locally
Casement window replacement quotes come from local installers who cover your postcode: they survey each opening, then quote supply and fit in writing. Tell us how many windows and which frame material you want, so every quote prices the same job.
- Supply and fit, not supply only. The installer measures every opening and handles the sign-off
- Name your escape windows. Say which upstairs casements you would climb out of in a fire
- Free and no obligation. Say no to every quote if none suit you
We are a free quote-matching service, not an installer.
The job
What a casement window replacement quote covers
A casement window replacement quote covers the survey, new frames and opening sashes, the glass, fitting and the building regulations sign-off, priced window by window. Check that every quote describes each window the same way:
| On the quote | Ask |
|---|---|
| Opening plan | Which panes are side hung, which are top hung and which are fixed, for every window? |
| Sash type | Storm-proof, where the opening sash sits on the frame, or flush, where it closes level with the frame? |
| Frame material | uPVC, aluminium or timber, and the same colour inside and out? |
| Glass | Double or triple, and safety glass in low panes and beside doors? |
| Fitting | Supply and fit, with the old frames removed and the openings made good? |
Bassetlaw District Council's casement guidance notes that traditional casements were set flush with the frame or recessed when closed, while many modern "off the peg" casements are storm proofed, with the opening sash sitting on top of the frame. It also says top hung casements "are often inappropriate in older properties", so on a period home ask for side hung sashes where the old ones were.
For the frame material, see our pages on getting an aluminium windows quote and on timber window replacement, or ask for uPVC in the form.
French casements
A French casement is a pair of side hung sashes that open from the middle. Ask for it as one line on the quote, and check the escape rules below: LABC says a fire escape window can be two side-opening casements with no fixed centre stile.
If only a sealed unit has misted and the frame is sound, a new unit may be all you need. LABC says the building regulations don't apply if you are simply replacing the glass, so that is a glass job, not a window replacement.
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Fire escape
Which of your casements are escape windows?
An escape window can only be replaced by a window with the same or bigger opening and the same type of hinges, according to LABC. Escape windows are usually side hung casements, so mark them before anyone measures up.
LABC sets out what an escape window needs:
- a clear openable area of at least 0.33m²;
- a clear opening at least 450mm wide or high, with the other side at least 750mm;
- the bottom of the opening no more than 1100mm above the floor;
- generally one escape window per room.
Approved Document B says a replacement window "should be sized to provide at least the same potential for escape".
Ask the surveyor
Which casement in each room is the escape window? Will the new one open as wide as the old one, on the same kind of hinge? Ask for both answers on the written quote, window by window.
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The rules
What new casement windows must meet
New casement windows in England must reach a U-value of 1.4 W/m²K or Window Energy Rating band B, keep background ventilation and use safety glass in low panes. The installer, or building control, signs the job off.
| Rule | What it means for your quote |
|---|---|
| Energy | Approved Document L sets 1.4 W/m²K or band B for replacement windows in England, in force since 15 June 2023. Ask for the figure of each whole window. |
| Ventilation | LABC says a replacement window must have vents if the old one did, and must not reduce the area that opens for ventilation. |
| Safety glass | Glass within 800mm of the floor, and glass within 300mm of a door edge and 1500mm of the floor, is a critical location (LABC). |
| Sign-off | An installer registered with FENSA or CERTASS self-certifies the work. Otherwise you apply to your local building control body for approval. |
Check a registration on the FENSA installer search or the Certified Competent search for CERTASS. In Scotland, replacement windows follow the Scottish building standards instead: see double glazing in Scotland.
Permission first
Do you need permission to replace casement windows?
A house in England can usually replace its casement windows without planning permission when the new ones look similar to the old. Flats, conservation areas with an Article 4 direction and listed buildings are the exceptions.
| Your home | What applies |
|---|---|
| House | New windows of a similar appearance to the originals are permitted development (Planning Portal). |
| Flat | Identical like-for-like windows should not need planning permission, but a change of size or glazing pattern may. See replacing windows in a leasehold flat for the lease side. |
| Article 4 direction | Historic England says these directions can restrict even replacing a window with one of a similar design. Ask the council first. |
| Listed building | Listed building consent is needed for alterations that affect the building's character, windows included. |
| Scotland | In a conservation area, a front window that changes its opening method, for example sash to casement, means notifying the council first (Planning Circular 1/2024). |
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Same style or new
Keep casements, or change the style?
Keep casements where they are your escape route, because LABC says escape windows are generally hinged at the side rather than being tilt and turn or pivoting. Changing style is a choice for the other windows.
- Sash look: for a period front that once had sashes, compare a sash option. See sash window replacement.
- Tilt and turn: ask how the opening meets the escape rule before you choose it for a bedroom.
- Flush casement: ask for a flush and a storm-proof price side by side, so you see what the flush look adds.
Before you sign
How to compare casement window quotes
Compare casement window quotes line by line on the same windows, not on the total. The Energy Saving Trust recommends getting quotes from at least three installers.
- One line per window, with its opening plan and sash type.
- The U-value or energy band of each window.
- Which windows get trickle vents, and which are escape windows.
- The guarantee, who backs it, and the scheme that signs the job off.
Our guide on how to compare double glazing quotes shows what a full quote lists, and the contract checklist covers what to check before you sign.
If you sign at home, you usually have at least 14 days to cancel, but made-to-measure windows can be an exception, so check the contract before you sign: see the double glazing cooling off period.
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FAQ
Casement window replacement: common questions
Who will contact me after I ask for quotes?
A short call confirms the job first. Local installers who cover your postcode then contact you to book a survey and send a written quote.
Is it worth replacing 20 year old double glazing?
It is worth replacing when the frames themselves have failed. If only a sealed unit has misted in a sound frame, a new unit may be enough, and LABC says replacing just the glass is not covered by the building regulations.
What is the difference between flush casement and standard casement windows?
A flush casement's opening sash closes level with the frame. A standard storm-proof casement's sash sits on top of the frame when closed. Bassetlaw District Council notes that traditional casements were always set flush or recessed.
What materials are best for casement windows?
No single material suits every home. The Energy Saving Trust says uPVC frames don't need regular maintenance, wooden frames are the more sustainable option and can last far longer with maintenance, and aluminium frames are slim and long lasting.
Do I need Building Regulations approval to replace a casement window?
Yes in England and Wales, but a FENSA or CERTASS registered installer self-certifies the work for you. Without one, you apply to your local building control body for approval (LABC). Scotland follows its own building standards.
How much does casement window replacement cost?
Each installer prices your windows after the survey, so compare written quotes; our sister site shows what a casement window costs fitted.
Get your casement window quotes
Answer a few questions, take one call to confirm the job, then compare written quotes from local installers. To start from the homepage, compare double glazing quotes.
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Sources
Rules checked 8 October 2026.
- Bassetlaw District Council, Guidance Note: Traditional Casement Windows (January 2011)
- LABC Front Door, fire escape windows, ventilation with windows and doors, safety glass and who can install windows and doors
- Approved Document B, Volume 1, dwellings (2019 edition, collated with later amendments)
- Approved Document L, Volume 1 (2021 edition incorporating 2023 amendments), Table 4.2
- FENSA, find an installer; Certified Competent, installer search
- Planning Portal, doors and windows: planning permission and changing the windows of a flat
- Historic England, what permission might I need?
- Scottish Government, Planning Circular 1/2024, section 7
- Energy Saving Trust, energy efficient windows and doors