Some home improvements can proceed without a full planning application. In England, permitted development is planning permission granted nationally, subject to limits and conditions. The address and the complete design determine whether it applies.
Horizon Architecture · Updated 17 October 2026 · England
Start with the property, not the maximum size
Householder rights do not generally apply to flats or maisonettes. Article 4 directions and earlier planning conditions can remove rights. Conservation areas and listed buildings need particular checks; some changes still require separate listed building consent. Earlier extensions can use up allowances, even if a previous owner built them.
Common projects: an initial screening checklist
| Project | What to check first |
|---|---|
| Single-storey rear extension | Ordinary depth limits are generally 3m for attached houses and 4m for detached houses, measured from the original rear wall. Height, boundaries and other conditions also apply. |
| Larger rear extension | Up to 6m for attached houses or 8m for detached houses may use the prior-approval route on eligible land. Complete the required process before starting. |
| Loft enlargement | Check added roof volume, roof position and the property’s designation. Dormers and roof alterations have specific conditions. |
| Garden room or outbuilding | Check its use, position, height and the cumulative area of buildings. Do not assume a separate dwelling is covered. |
| Porch or rooflights | Small changes have their own limits. Their size alone does not establish compliance. |
This is a screening list, not a complete permission checklist. Use the government’s householder technical guidance to check every relevant condition.
When is prior approval needed?
The larger-home-extension route includes notification to the council and neighbour consultation. It is not permission to start building immediately after sending a form. The applicable procedure must be completed before work begins; check the council’s response and the relevant conditions. This route is not available on all land, including conservation areas.
A rear-extension design review should establish the route before you commit to a depth or a contractor.
What is a lawful development certificate?
A proposed lawful development certificate records the council’s formal assessment that the specified proposal would be lawful. It is different from a planning application judged against local design policy. Accurate plans and evidence are important; the certificate relates to the proposal described, not any later redesign.
See government guidance on lawful development certificates. Keeping the certificate and approved drawings with your property records can help answer questions when you sell.
Planning is only one part of the checks
A permitted development route does not settle structural design, fire safety, drainage or energy performance. Discuss Building Regulations drawings and the appropriate Building Control route. Check separately for Party Wall procedures, sewer approvals and restrictions affecting the property.
For London homes, investigate conservation-area status, trees, boundary relationships and the planning history early. A project that needs a full planning application may still be achievable with a carefully developed design.
Before you instruct a builder
- Confirm whether the property has the relevant rights.
- Measure the original house and record previous additions.
- Check the whole proposal against every applicable limitation and condition.
- Agree the certificate, prior-approval or planning application route.
- Complete the separate technical and consent checks before starting.
Use our construction cost calculator for an early budget and architect fees guide to understand design-stage costs.
Frequently asked questions
Does permitted development mean no paperwork?
No. Evidence of compliance, a lawful development certificate and, for some proposals, prior approval may be relevant. Building Regulations and other consents remain separate.
Can I build a 6m extension to any London terrace?
No. The larger-extension route depends on eligibility, measurements and conditions, and requires the prior-approval procedure. Check the property before relying on the maximum depth.
What if my project falls outside the limits?
Discuss a planning application or a revised design. Exceeding a permitted development limit does not automatically mean a proposal cannot receive planning permission.
Check the planning route for your home
Send the property address, existing plans and a description of the proposed changes.
Discuss your projectSources and scope
Guidance checked 17 October 2026. General information for homes in England; confirm the current requirements and agreed fees for your property before proceeding.
