A standard uPVC casement window costs £350 to £600 fitted in 2026. Doing a whole 3-bedroom house comes to roughly £4,000 to £6,000 in uPVC, supply and fit, VAT included. Aluminium and timber frames cost more, and the style of window, the number of opening sections and access all move the figure.
This guide breaks the price down by window, by house, and by the extras that do not always appear on the first quote.
Points to take away
- uPVC casement: £350 to £600 per window fitted. Whole 3-bed house: £4,000 to £6,000.
- Aluminium is roughly 1.5 to 2 times uPVC. Timber is 2 to 3 times.
- National sales firms typically quote 15 to 30 percent above a good local installer.
- Double glazing for an existing home carries 20 percent VAT. It is not zero-rated.
- A misted unit can be reglazed for £70 to £150 rather than replacing the window.
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Double glazing cost per window
Prices are fully fitted, including VAT, for a Building Regulations compliant window from a FENSA or CERTASS registered installer.
| Window | uPVC | Aluminium | Timber |
|---|---|---|---|
| Casement (side-hung) | £350 to £600 | £600 to £850 | £950 to £1,400 |
| Sash / sliding | £700 to £1,500 | £900 to £1,600 | £1,200 to £2,000 |
| Bay window | £1,200 to £2,500 | £1,800 to £3,500 | £2,500 to £4,500 |
| Fixed / non-opening | £200 to £400 | £350 to £550 | £500 to £800 |
| Tilt and turn | £450 to £750 | £700 to £1,000 | not common |
Supplements to expect: coloured or woodgrain foil adds roughly 10 to 20 percent, argon-filled A-rated glass adds £20 to £40 per window over a C rating, and decorative or obscure glass adds £30 to £80.
Whole-house cost by property size
| Property | Windows | uPVC | Aluminium |
|---|---|---|---|
| Flat or terrace | 4 to 6 | £2,200 to £3,800 | £3,800 to £6,000 |
| 3-bed semi | 8 to 10 | £4,000 to £6,000 | £7,000 to £10,000 |
| 4-bed detached | 12 to 16 | £6,500 to £10,000 | £11,000 to £16,000 |
The per-window price drops when you do the whole house at once, because the visit, any scaffold and the waste disposal are shared across every opening.
Doors and bay windows
- uPVC front or back door: £800 to £1,200 fitted
- Composite front door: £900 to £1,800
- French doors: £1,000 to £2,500
- Patio (sliding) doors: £1,200 to £3,000
- Bifold doors, 3 panel: £2,000 to £5,000
A bay window costs more than a flat window of the same glass area because it needs a structural head or a load-bearing frame to carry the wall above it.
The extras people forget
A quote for “the windows” sometimes leaves these out. Ask.
- Scaffold or a cherry picker for anything above the ground floor: £300 to £800.
- Making good: plastering and filling around the new frames, £50 to £100 per window if the installer does it at all. Many leave it to you.
- A new lintel if the existing one is failing or absent: £300 to £600 per opening.
- Skip hire for the old frames and glass: £200 to £350.
- Trickle vents, now required by Building Regulations on most replacements, usually included but worth confirming.
Why national quotes come in higher
The same uPVC casement window fitted by a national sales-led company often costs 15 to 30 percent more than through a local installer doing the same work. The gap pays for the salesperson, the advertising, the showroom and the head office. Long “buy now, pay monthly” finance deals add interest on top, often £1,000 or more over the term.
That does not make nationals a bad choice, but it does mean their first price is rarely their best, and a local quote is worth getting to compare. Our guide on how to compare double glazing quotes covers what to look for line by line.
Replace the pane, or the whole window?
If the frame is sound and only the glass has misted up because the seal has failed, you do not need a new window. An installer can fit a fresh sealed unit into the existing frame for £70 to £150 per pane. A whole new window is £350 upwards. Our guide to misted and foggy double glazing explains when reglazing works and when the frame has gone too.
How to get the best price
- Get three quotes, at least one from a local FENSA or CERTASS installer.
- Do the whole house in one order if you can, for the volume discount and a single certificate.
- Ask for the price in cash terms, not just a monthly figure. Work out the total with interest before agreeing finance.
- Match the spec across quotes: frame material, glass energy rating, number of opening sections, colour. “New windows” is not comparable.
- Book outside spring and early summer if timing is flexible. Demand and prices ease in autumn and winter.
Whether double glazing pays back on energy bills alone is a separate question. Our guide on whether double glazing is worth it runs those numbers.
Ready to compare? Get a free quote and we will match you with vetted local installers who cover your area.