A conservation area does not change how many windows your home has, but it can change what you are allowed to fit, and that is where the cost moves. The good news is that replacing windows like-for-like is often permitted development that needs no planning permission. The catch is the Article 4 direction: where one is in force, you need permission, and the council can insist on timber or heritage frames that match the original. This page covers the money only, so for the planning side see our guide to the conservation area rules; here it sets out when you pay the standard rate and when you pay the heritage premium. For a property that is also a period terrace, see our Victorian terrace cost page.
What you pay depends on Article 4
The single biggest cost factor in a conservation area is whether an Article 4 direction applies to your street. Without one, you can usually replace windows like-for-like as permitted development and pay the ordinary rate for your house size. With one, the council can require planning permission and dictate the material, and new uPVC frames are frequently refused on the principal elevation facing the highway. The table shows what each outcome does to the figure for a mid-sized home.
| Scenario | Likely material | Typical whole-house cost |
|---|---|---|
| No Article 4, like-for-like | uPVC casement or sash | £4,000 to £10,000 |
| Article 4, rear elevations | uPVC often accepted | £4,000 to £10,000 |
| Article 4, front elevation | Timber or heritage required | £10,000 to £18,000+ |
Source: DGCC 2026 dataset for the figures; planning position from gowercroft.co.uk, hugocarter.co.uk and thesoundproofwindows.co.uk.
Why Article 4 forces the timber premium
A conservation area protects the character of a place, and windows are one of the most visible parts of that character. An Article 4 direction is the tool councils use to keep control of changes that would normally be permitted, and the most common condition is that replacement windows match the original in material and sightline. On a Victorian or Georgian street that usually means timber, which runs 60 to 110% more than uPVC per window. The premium is not the installer overcharging, it is the planning requirement. The way to soften it is to use slimline double glazing or heritage aluminium, which keeps the thin original sightline at less than the cost of full timber and is accepted by many conservation officers.
Phone the conservation officer before you order anything. Half the streets people think are locked down have no Article 4 at all, and you can fit sensible windows like-for-like. The other half do, and then it is timber or slimline on the front whether you like it or not. Find out which you are in first, because it doubles the budget on the front elevation.
Tom Bradley, FENSA-registered installer
Best Buy in a conservation area
Where you are free to choose, like-for-like uPVC Best Buy keeps you at the standard rate. Where Article 4 bites on the front, slimline or heritage glazing Worth it is the sensible compromise, matching the sightline without full timber prices. Full timber sash It depends is reserved for where the council insists or the house genuinely warrants it, priced in the timber window calculator. If your home is also listed, the rules tighten further on our listed building cost page.
Frequently asked questions
Often yes. Replacing windows like-for-like in a conservation area is generally permitted development and does not need planning permission, unless an Article 4 direction is in force. Where Article 4 applies, planning permission is required and new uPVC frames are commonly refused, especially on front elevations.
An Article 4 direction removes some of the permitted-development rights you would normally have in a conservation area. In practice it means you must apply for planning permission to change your windows, and the council can insist on like-for-like timber or heritage frames that match the original.
On window count it is the same as any comparable house, but where Article 4 forces timber, you pay the timber premium of roughly 60 to 110% over uPVC. A job that would cost £6,500 in uPVC can therefore run £10,000 to £14,000 or more in like-for-like timber.
It depends on whether an Article 4 direction applies and on the elevation. On a rear or hidden elevation, uPVC is often accepted. On a principal elevation facing the highway under Article 4, uPVC and obvious double glazing are frequently refused in favour of timber or slimline heritage units.
It can be. Slimline double glazing and heritage aluminium keep a thin sightline that matches the original glazing bars, which makes approval more likely on a restricted elevation. It costs more than standard uPVC but less than full timber, and it satisfies many conservation officers.