What are permitted development rights?
Permitted development rights are a national grant of planning permission. They let certain building works go ahead without a planning application, as long as the work stays within set limits and conditions.
For many homeowners this means a kitchen extension, a garden room or a modular extension can start sooner than a project that needs a full application. The condition is that you design within the rules, and stay within them while you build.
When you may not need planning permission
You will often not need a planning application if the extension stays inside the permitted development criteria for houses. The main conditions usually include:
- The extension, together with other buildings, covers no more than half of the land around the original house.
- It is no higher than the highest part of the existing roof.
- A single-storey rear extension does not extend beyond the original rear wall by more than 4 metres for a detached house, or 3 metres for other houses. Larger single-storey extensions may be possible through the prior approval process.
- Materials are similar in appearance to the existing house.
- There are no verandas, balconies or raised platforms.
The exact limits are set out in government guidance and are updated from time to time. Check the current figures on the Planning Portal before you rely on them.
When you will need planning permission
Permitted development does not apply everywhere. You are likely to need a planning application if:
- You live in a flat or maisonette. Permitted development rights for extensions apply to houses.
- Your home is in a designated area such as a Conservation Area, a National Park, an Area of Outstanding Natural Beauty (now known as a National Landscape) or a World Heritage Site.
- The property is a listed building.
- The extension goes beyond the height or depth limits.
- You want to build forward of the principal elevation, usually the front of the house facing the road.
- Your rights have been removed by an Article 4 direction or a condition on an earlier permission.
If any of these apply, speak to your local planning authority early. A pre-application conversation costs far less than a refused scheme.
Do you still need Building Regulations approval?
Yes. Planning permission and Building Regulations are separate. Skipping one does not skip the other.
Planning looks at how a building looks, how big it is and where it sits. Building Regulations cover structure, insulation, fire safety, ventilation and drainage. A substantial extension, including a modular one such as BLOXX Home, must comply with Building Regulations whatever its planning status.
Does the way you build matter?
It can. A modular extension is manufactured off-site in a controlled environment, so the finished size is fixed before anything arrives on your drive.
That matters under permitted development. On a traditional site, small changes during the build can push an extension past a limit and trigger the need for a retrospective application. With an off-site build, what is drawn is what is delivered and installed.
Key questions to settle before you design
- Is the property a house, and is it in a designated area?
- Have permitted development rights been removed by an Article 4 direction or an earlier planning condition?
- Do you need prior approval for a larger single-storey extension?
- Who is handling Building Regulations, and when will building control inspect?
BLOXX Home projects start with a consultation that covers these questions for your site. The planning support BLOXX provides on each project is agreed at that stage.
Key takeaways
- Many single-storey extensions can be built under permitted development, which saves time and planning fees.
- Check whether your home is in a designated area, or whether an Article 4 direction has removed permitted development rights.
- Building Regulations approval is needed whether or not planning permission is.
- Off-site manufacture makes it easier to build exactly what was drawn, which helps you stay inside the limits you designed to.
Planning a BLOXX Home extension?
Tell us about the house and the space you want. We will talk you through the planning position for your site and what we need to design it.
