It’s one of the first questions we get asked on a site visit. The short answer is: not always. A lot of extensions can be built under what’s called permitted development, which means you don’t need to apply for full planning permission. But there are limits, and getting it wrong can be an expensive mistake.
Here’s a plain English guide to the rules for houses in England, based on the government’s Planning Portal guidance.
What is permitted development?
Permitted development rights let you make certain changes to a house without a planning application, as long as you stay inside set limits. They only apply to houses, not flats or maisonettes, and some areas have them removed or reduced.
Single storey rear extensions
- Up to 3 metres deep from the original back wall on a semi or terrace, or 4 metres on a detached house
- No higher than 4 metres
- Eaves no higher than 3 metres if the extension is within 2 metres of the boundary
There’s also a larger home extension scheme that allows up to 6 metres on a semi or terrace and 8 metres on a detached house. For that you have to tell the council first through a prior approval application, and your neighbours get the chance to comment.
Side extensions
Side extensions have to be single storey, no higher than 4 metres and no wider than half the width of the original house.
Two storey extensions
A two storey rear extension can go up to 3 metres beyond the original back wall, as long as it’s at least 7 metres from the boundary behind. The roof pitch should match the house and any upstairs side windows need obscure glass.
Other rules to bear in mind
- Materials should look similar to the existing house
- Extensions and outbuildings can’t cover more than half the land around the original house
- The original house means the house as it was first built, or as it stood on 1 July 1948, so any earlier extensions count towards your limits
When you will need planning permission
- If the house is in a conservation area, side extensions and rear extensions of more than one storey need planning permission
- If the council has an Article 4 direction that removes permitted development rights
- If the property is a flat or maisonette
- If it’s a listed building, you’ll need listed building consent for most work
- If your extension goes beyond any of the limits above
There are a number of conservation areas in and around Chelmsford, so it’s always worth checking before you start.
Get it in writing
Even if your extension falls under permitted development, we’d always recommend applying to the council for a Lawful Development Certificate. It confirms the work is legal and makes life much easier when you come to sell the house.
And remember, planning is only half of it. Almost every extension still needs building regulations approval, which covers things like foundations, insulation, drainage and fire safety.
We can sort it all for you
Because our team includes an architect and planning consultant, we can check your house, tell you what you can build, draw it up and deal with the council for you. Then our own team builds it.
If you’re thinking about an extension in Chelmsford or anywhere in Essex, get in touch for a free site visit or call us on 07747 022565. You can also read more about our house extensions and our architecture and planning service.
This is a general guide to the rules in England. Every house is different, so always check with us or the council before you start.