How many windows does an average UK house have?

Eight to twelve is typical. A three-bedroom semi is usually around nine, a terrace often fewer because it has no side elevation, and a detached house more.

Will new windows add value to my house?

They tend to help a sale more than they add a measurable amount to the price, particularly where the existing windows are visibly failed. Treat comfort and running costs as the return, not an uplift.

Should I replace all the windows or just the bad ones?

If several have failed and the rest are the same age, whole-house is usually better value and looks consistent. If one unit has misted in an otherwise sound window, that is a repair.

Costs by property

How much does a full house of windows cost?

Most UK houses have eight to twelve windows. Taking ten as the average, replacing all of them in uPVC typically costs between £4,000 and £8,500 supplied and fitted, with aluminium around half as much again and timber higher still. Doing the whole house at once is cheaper per window than replacing them one at a time.

This is the question people actually ask, and the one almost nobody in the trade will answer in public. Here is the arithmetic, with the source for every figure.

Worked example

10 windows

uPVC: £4,000 – £8,500
aluminium: £6,000 – £12,500
timber: £8,000 – £16,000

£4,000 – £8,500

supplied and fitted, uPVC

These figures come from published industry price guides, not official statistics, and several of those sources are installers or comparison sites with a commercial interest. They are a starting point for a conversation, not a quote. Your installer sets the actual price after measuring.

Costwise UK new windows cost guide · checked 2026-10-09
Checkatrade double glazing cost guide · checked 2026-10-09

Why doing them all at once is cheaper

A single window replacement carries the full cost of the survey, the delivery and the setting up. Spread across nine windows those costs almost disappear, which is why a whole-house price per window is noticeably lower than a one-off.

The practical saving is real but it is not enormous, and it is not a reason to replace windows that are working. It is a reason not to drip-feed a replacement you have already decided on.

Where the money actually goes

The frames and glass are the bulk, but the variable parts are what move one quote away from another:

Upper-floor access. Anything needing scaffolding rather than ladders adds a day and a hire cost.
Bay windows. Often structural, and priced separately from the flat openings.
Making good. Plaster, trims and sill boards inside. The single most common gap between two quotes.
Disposal. Taking the old frames and glass away is a cost; check it is in the price.

Doing it in stages

If the whole house is beyond budget, stage it by elevation rather than by room. Doing the front in one go keeps the appearance consistent, and doing the most exposed elevation first puts the money where the heat and weather are.

Ask the installer to quote the whole house and the stages separately, so you can see what the staging actually costs you.

Questions

How many windows does an average UK house have?: Eight to twelve is typical. A three-bedroom semi is usually around nine, a terrace often fewer because it has no side elevation, and a detached house more.
Will new windows add value to my house?: They tend to help a sale more than they add a measurable amount to the price, particularly where the existing windows are visibly failed. Treat comfort and running costs as the return, not an uplift.
Should I replace all the windows or just the bad ones?: If several have failed and the rest are the same age, whole-house is usually better value and looks consistent. If one unit has misted in an otherwise sound window, that is a repair.