Can I replace my windows?
Like-for-like window replacement usually needs no planning permission — but it must comply with Building Regulations. Replacing windows in a house is permitted development, so no planning permission is required. However, windows are "controlled fittings," so the work must meet Building Regs: either use a FENSA or CERTASS-registered installer who self-certifies and notifies the council within 30 days, or (if doing it yourself) submit a Building Notice and get a completion certificate. The replacements must meet thermal standards (typically a U-value of 1.4 or a Window Energy Rating of Band C), keep adequate ventilation (usually trickle vents) and escape openings, and use safety glazing where needed. Listed buildings need consent even for identical windows, and conservation areas may restrict changes like timber to uPVC. In short: usually yes, but you need the right Building Regs paperwork.
📋 The rules
- Like-for-like in a house: no planning permission (PD)
- Windows are controlled fittings — Building Regs apply
- Use a FENSA/CERTASS installer, or notify Building Control
- Meet thermal, ventilation, fire-escape and safety-glazing rules
- Listed buildings need consent; conservation areas restrict
🔓 Exceptions
- Flats and maisonettes: permitted development doesn't apply
- Conservation areas / Article 4: timber-to-uPVC may need permission
- New upper-floor side windows must be obscure-glazed and high or fixed
⚠️ Penalties & fines
There's no planning fee for like-for-like, but the certificate matters: contravening Building Regulations can mean an unlimited fine plus daily fines, and you can apply for a Regularisation Certificate for uncertified past work (a few hundred pounds). Missing a FENSA or Building Control certificate very commonly stalls a house sale. Unauthorised work to a listed building is a criminal offence (unlimited fine and/or up to 2 years). Beware a myth: "like-for-like windows need no paperwork" is false — even identical swaps are controlled fittings needing a FENSA/CERTASS or Building Control certificate, and not having one often holds up a sale. (Scotland uses a Building Warrant, not FENSA; Northern Ireland notifies its district council.) Before replacing: use a FENSA or CERTASS installer (or notify Building Control yourself), keep the certificate safe, and check whether your home is listed or in a conservation area.
📎 Official sources
- Planning Portal — doors and windows: planning →
- FENSA — building regulations for homeowners →
- GOV.UK — Approved Document L 2026 →
❓ Frequently asked
Do I need planning permission to replace my windows?
Usually not. Replacing windows on a like-for-like basis in a house is permitted development, so no planning permission is needed. However, you must comply with Building Regulations, and there are exceptions: flats, listed buildings and properties in conservation areas, where changes to windows can require listed building consent or planning permission.
What is FENSA?
FENSA, along with CERTASS and BSI, is a Competent Person Scheme for window and door installers. A FENSA-registered installer can self-certify that replacement windows meet Building Regulations and notify the council, issuing you a certificate. This avoids needing to involve Building Control directly. If your installer isn't registered, you must notify Building Control yourself.
Do replacement windows have to meet energy standards?
Yes. Replacement windows are controlled fittings and must meet thermal performance standards under the Building Regulations — typically a maximum U-value of 1.4, or a Window Energy Rating of Band C or better. They must also maintain adequate ventilation, usually via trickle vents, and provide adequate escape and safety glazing where required.
Can I change the windows in a listed building?
Only with listed building consent. In a listed building, replacing windows, even with an identical design, requires listed building consent because of the impact on the building's character. Carrying out unauthorised works is a criminal offence. In conservation areas, changing materials, such as timber to uPVC, may also need planning permission.
Why does my window certificate matter?
Because it proves the work met Building Regulations. When you sell your home, the buyer's solicitor will typically ask for a FENSA, CERTASS or Building Control completion certificate for any windows replaced since 2002. Missing certificates frequently delay or jeopardise sales, and you may have to pay for a Regularisation Certificate or indemnity insurance.
🔎 Common searches
What people search to land here:
- “can i replace my windows uk”
- “do i need permission to replace windows”
- “fensa certificate windows”
- “replacing windows building regulations”
- “windows listed building consent”
- “window u value building regs”