A flat is the cheapest property type to double glaze on raw window count, usually around 4 windows, which on our cost by house size guide sits at about £3,200 fully fitted in uPVC. But a flat is the one case where the price is not the hard part. The lease is. Before you can fit a single window you generally need the freeholder's consent, and that can come with conditions, fees and planning questions a house owner never faces. This page covers both halves: the real 2026 figures, and the permissions that decide whether you can use them. On upper floors, price your windows in the tilt and turn calculator.
What a flat costs, fully fitted
The table below pairs a realistic window count with a fully fitted uPVC price. The high column reflects larger windows, a premium glass package or an upper-floor flat where access adds to the labour.
| Flat type | Typical windows | Low | Average | High |
|---|---|---|---|---|
| Studio / one-bed | 2 to 3 | £1,200 | £2,400 | £3,800 |
| Two-bed flat | 4 | £1,800 | £3,200 | £5,000 |
| Three-bed / upper-floor | 5 to 6 | £2,600 | £4,200 | £6,500 |
Source: DGCC 2026 dataset. Figures exclude freeholder admin fees and any communal or service-charge works.
The lease matters more than the price
Under most leases, the windows are either demised to your flat or remain the freeholder's responsibility, and either way you usually need written consent before changing them. Freeholders commonly require the new windows to match the rest of the block in style and colour, and many charge an administration or licence-to-alter fee simply to process the request. One documented case put that at around £500 plus a £90 admin fee, before any windows were even ordered. Get the consent and the conditions in writing before you book an installer.
Planning is the second trap. Flats do not enjoy the permitted-development rights that houses have, so a council can require planning permission to replace windows even on a flat that is not listed and not in a conservation area. And where the freeholder decides to replace windows across the whole block, the cost is recovered through the service charge: on a large building that has run to tens of thousands of pounds per leaseholder. None of this changes the per-window price, but all of it changes whether, and when, you can spend it.
I turn down flat jobs every month because the owner has not asked the freeholder yet. The windows are the easy bit. Get the freehold consent in writing first, check whether the managing agent wants a specific colour and frame, and only then call me. Fit without permission and you can be made to rip them out.
Tom Bradley, FENSA-registered installer
Best Buy for a flat
Where the lease leaves you a free choice, uPVC Best Buy is the value pick, and on upper floors a tilt and turn Worth it is worth it because it swings inward for safe cleaning from inside, which matters when you cannot reach the outside of the glass. If the building qualifies for support, a whole-block upgrade may attract funding, so it is worth checking our double glazing grants guide before the freeholder sets the bill.
Frequently asked questions
A typical flat has around 4 windows and costs £1,800 to £5,000 fully fitted in uPVC, with an average near £3,200. The bigger variable is usually not the windows themselves but the leasehold permissions and any access or scaffolding for upper floors.
Almost always, yes. Under most leases you need the freeholder's written consent before changing windows, and the lease may set the style and material so the block stays uniform. Freeholders often charge an administration or licence-to-alter fee to process it, sometimes a few hundred pounds.
They can. Flats do not have the permitted-development rights that houses have, so planning permission may be required to replace windows even when the flat is not listed or in a conservation area. Check with your local planning authority before you commit.
It depends on the lease. Where windows are demised to your flat, you pay. Where they are communal or the freeholder organises a block-wide replacement, the cost falls under the service charge, which can be a very large sum per leaseholder. Read your lease before assuming the responsibility is yours alone.
On upper floors, tilt and turn windows are popular because they swing inward so you can clean the outside safely from inside. uPVC is the usual value choice, but the lease may dictate the material and style to match the rest of the building.