Thinking about extending your home but not sure if you’ll need to get planning permission? At Garnet Construction, we’re often asked: “how big can a rear extension be without planning permission?”
The good news is, under Permitted Development Rights, many homeowners can extend their property without going through the full planning process – but there are key rules you need to follow.
What is Permitted Development?
Permitted Development Rights (PDR) are a set of guidelines set by the government that allow homeowners to make certain improvements to their property without applying for planning permission. These rules are designed to make it easier for homeowners to extend their living space – perfect for adding a new kitchen, family room, or home office.
So, How Big Can Your Rear Extension Be Without Planning Permission?
The maximum size for a rear extension under permitted development depends on the type of property you have:
Detached houses: You can extend up to 8 metres beyond the original rear wall.
Semi-detached and terraced houses: The limit is 6 metres beyond the original rear wall.
These allowances apply to single-storey rear extensions and are subject to certain conditions and limitations.
Key Conditions for Permitted Development Rear Extensions
Even if your extension falls within the 6 or 8-metre limit, there are additional rules you must meet to qualify for permitted development:
- The extension must not be taller than 4 metres.
- It cannot be higher than the existing roof of your house.
- The extension, along with other outbuildings, must not cover more than 50% of your garden.
- Materials used should be similar to the existing property (unless in a conservation area).
- No balconies or verandas are allowed under permitted development.
- In many cases, you’ll also need to submit a prior approval application to your local council, especially for larger rear extensions (over 4 metres but within the 6 or 8-metre limits).
What About Two-Storey Rear Extensions?
Two-storey rear extensions do not fall under standard permitted development rights and will require full planning permission, especially if they come close to your boundary line or affect neighbouring properties.
When Permitted Development Might Not Apply
There are scenarios where permitted development won’t apply, and you’ll need planning permission regardless of size:
- If your home is in a conservation area or Area of Outstanding Natural Beauty (AONB).
- If your property is a listed building.
- If previous owners have already used up your permitted development rights.
Should You Still Check With Your Local Council?
Yes! While many projects fall under permitted development, it’s always recommended to check with your local council or work with professional builders like Garnet Construction to ensure compliance. We can help you secure a Certificate of Lawfulness, giving you peace of mind that your extension is fully permitted.
Why Choose Garnet Construction?
As trusted builders in Hertfordshire and Essex, we’ve completed countless rear extensions under permitted development guidelines. We offer a full service, including:
- Site surveys
- Design and layout recommendations
- Permitted development checks
- Build and project management from start to finish
- Whether you’re based in St Albans, Bishop’s Stortford, Hertford, or anywhere across North London and Essex, we’re here to help you expand your home stress-free.
Let’s Get Your Project Moving
Thinking about a rear extension and want to make sure you stay within permitted development? Contact Garnet Construction today for expert advice and a free consultation.