Do you need planning permission for windows UK?

You can replace most windows like-for-like without planning permission

If you are replacing an existing window with one of the same size, shape, and appearance, you can almost always proceed without applying for planning permission. This is because like-for-like replacements are classified as permitted development under the Town and Country Planning (General Permitted Development) Order (GOV.UK, 2026). The rule applies to houses, not flats or maisonettes, and only when the new windows are a close match in appearance, size, and position.

There are important exceptions. If you live in a listed building, a conservation area, a National Park, an Area of Outstanding Natural Beauty, or the Broads, different rules apply and you may need consent even for a like-for-like swap. You should also check your property deeds for any restrictive covenants that could override your permitted development rights (GOV.UK, 2026).

The single most important rule planning permission windows is needed when you change size, position, or style

Planning permission for windows is required if you are not carrying out a like-for-like replacement. Any change that alters the external appearance of the property – such as enlarging a window, adding a new one, changing from a casement to a sliding sash, or altering the opening angle – is considered development and needs an application (Planning Portal, 2026). Installing a window in a new location, even if it matches the style of existing windows, is not like-for-like and requires permission.

The key point is that the planning system controls what your house looks like from the outside. If the change is visible to neighbours or passers-by, you should assume you need permission unless you have confirmed otherwise. A Lawful Development Certificate (LDC) from your local council can give you formal confirmation that your work is permitted development (Planning Portal, 2026).

Quick numbers key dimensions and distances that trigger permission (table)

Listed buildings and conservation areas you almost certainly need listed building consent or planning permission

If your property is a listed building, any window replacement – even like-for-like – requires listed building consent from your local planning authority (Historic England, 2026). This is because the window is considered part of the building’s historic character. Unauthorised work can result in enforcement action and a requirement to reinstate the original windows.

In a conservation area, you cannot install new windows in a side elevation that are visible from a highway without planning permission. The removal or alteration of a window that is a “positive feature” of the building may also require consent (GOV.UK, 2026). If you are unsure whether your property is in a conservation area, check your local council’s website or the Planning Portal map.

How to verify your installer and avoid a retrospective planning application

Use an installer registered with FENSA or CERTASS for windows and doors. These bodies self-certify compliance with Building Regulations, which is a separate requirement from planning permission (GOV.UK, 2026). For work that does need planning permission, your installer should not start work until you have a decision notice. Using a non-registered installer can lead to enforcement action and potentially a requirement to remove the windows.

If you are unsure whether your project requires permission, apply for a Lawful Development Certificate (LDC) from your local council. This is a formal confirmation that your work is permitted development and can cost between £100 and £300 depending on the council (Planning Portal, 2026). An LDC is not mandatory, but it gives you legal certainty and can be useful if you sell the property later.

How to choose a FENSA registered window installer

Who qualifies for grants or funding that may affect your window plans

The Great British Insulation Scheme and the Home Upgrade Grant (HUG2) cover window replacement only in specific circumstances. Typically, your property must be off the gas grid and have an Energy Performance Certificate (EPC) rating of D, E, F, or G (GOV.UK, 2026). The Energy Company Obligation (ECO4) scheme can fund window replacement if the property has an EPC rating of E, F, or G, and the windows are single-glazed or have a U-value worse than 1.6 W/m²K (DESNZ, 2026).

Eligibility for all schemes is means-tested or based on specific qualifying benefits. You must use an installer registered with the scheme, typically on the TrustMark or MCS register (DESNZ, 2026). If you qualify, the grant can cover part or all of the cost of upgrading to double or triple glazing, but you must meet the scheme’s specific criteria before ordering any windows.

The two-step check planning permission vs. building regulations approval

Planning permission controls the appearance and location of windows. Building regulations approval controls the energy efficiency (U-value), safety (glazing safety zones), and ventilation (trickle vents). These are separate processes (GOV.UK, 2026). Most like-for-like replacements will not need planning permission but will need Building Regulations compliance. A FENSA-registered installer can self-certify this.

Always confirm both before ordering windows. A window that meets building regulations may still need planning permission if its appearance differs from the original. Conversely, a window that has planning permission may still need to meet building regulations standards. The safest approach is to check both with your installer and, if in doubt, apply for an LDC for planning and use a registered installer for building control (Planning Portal, 2026).