Do you need planning permission to replace windows?

The four situations where you do need consent

• Listed buildingListed building consent is required for window replacement, regardless of material, and doing it without consent is a criminal offence. Get pre-application advice.
• Article 4 directionMany conservation areas have one. It removes permitted development rights, which means the window replacement that would be automatic elsewhere now needs planning permission. Check with the council before you order.
• Flats and maisonettesPermitted development rights do not apply to flats at all. Planning permission is normally required, and the freeholder or management company will usually have their own conditions on top.
• Front elevation in a conservation areaEven without Article 4, changes to a principal elevation facing a highway are frequently restricted.

What conservation officers actually accept

The recurring objection is not the material — it is the sightline. A chunky profile that visibly thickens the frame changes the character of the elevation, and that is what gets refused.

A slim, flat-faced aluminium heritage profile, in the right colour, with a putty-line bead and genuine glazing bars, is routinely accepted — particularly on buildings that originally had steel windows, where it is the closest available match. The same officer will typically refuse a standard uPVC profile on the same building.

The practical advice: get the profile drawing from the supplier, take it to the conservation officer, and ask before you order. A pre-application conversation costs nothing and takes a fortnight; an enforcement notice costs a great deal more.

Building regulations are separate

Even where you do not need planning permission, replacement windows are still notifiable under building regulations. That is handled either by a FENSA or CERTASS registered installer self-certifying, or by a building control application. It is a different process from planning and you may need both.