Knowing which route applies to your project early on saves time, money and stress. At Kev Construct we guide homeowners across Edgware, Barnet, Enfield and Harrow through this every week, so here is a plain-English explanation.
What is the difference between permitted development and planning permission?
Permitted development is a set of national rules that let you make certain changes to your home without applying for planning permission. Planning permission is a formal application to your local council, which reviews the design, size and impact on neighbours before deciding.
If your extension fits inside the permitted development limits, you can often proceed without a planning application. If it goes beyond them, you apply to the council and wait for a decision, which typically takes around eight weeks for a straightforward householder application.
When can you build without planning permission?
Many single-storey rear extensions qualify as permitted development within the limits. As a general guide, the following often applies, although you should always confirm with your council or a professional:
- Single-storey rear extensions within depth and height limits
- Projects that do not cover more than half the garden or land around the original house
- Materials that are similar in appearance to the existing house
- Homes that are not flats, maisonettes or listed buildings
We always recommend applying for a Lawful Development Certificate. It is not compulsory, but it gives you written proof from the council that the work is lawful, which is very useful when you sell.
When do you definitely need planning permission?
You will usually need planning permission if your project involves any of the following:
- A double-storey or two-storey extension
- A front extension facing a road
- A side extension in many cases
- A home in a conservation area or a listed building
- Anything that exceeds the permitted development size limits
Conservation areas and listed buildings have tighter rules, so it is worth checking your address on your council's website before you plan anything.
What about building regulations and the Party Wall Act?
Planning permission and building regulations are two separate things, and this catches many people out. Even if your extension is permitted development, it still needs to meet building regulations for structure, insulation, drainage and safety. Building control sign-off confirms the work is safe and compliant.
If your extension sits on or near a shared boundary, the Party Wall Act may also apply. That means giving formal notice to your neighbours before work starts. We help you understand when this applies and keep things neighbourly.
Here is a quick guide to typical timescales:
With a Checkatrade rating of 9.67/10 from verified reviews, we pride ourselves on getting the paperwork right, not just the brickwork.
Frequently asked questions
Do you need planning permission for a rear extension?
Often not. Many single-storey rear extensions are permitted development within the size limits. Larger, double-storey or side extensions usually need planning permission.
What is a Lawful Development Certificate?
It is written confirmation from the council that your permitted development work is lawful. It is optional but very helpful when selling your home.
Does permitted development mean I can skip building regulations?
No. Building regulations apply to almost all extensions regardless of planning, covering structure, insulation, drainage and safety.
Want to know which route fits your home? Explore our full house extensions service and get a free estimate. Marian will give you clear, honest advice with no hidden fees.
