Permitted Development Extension: What You Can Build Without Planning Permission

When you want to add space to your home without the hassle of a full planning application, a permitted development extension, a type of home improvement allowed under UK building regulations without needing formal planning permission. Also known as PD rights, it lets homeowners expand their property within strict limits—think side extensions, loft conversions, or rear additions—without waiting months for approval. This isn’t a free pass to build anything big, though. The rules are tight, and crossing even one line can turn your dream project into a legal mess.

Permitted development extension rules vary by location, but in England, most homes can add a single-storey rear extension up to 6 meters deep (or 8 meters if it’s a detached house). The extension mustn’t extend beyond the rear wall of the original house by more than half the width of the original property. Height matters too—no part of the extension can be higher than the highest point of the existing roof. If you’re thinking about a two-story extension, it’s even trickier: it must be at least 7 meters from the boundary and can’t be closer than 2 meters to any side boundary. These aren’t suggestions—they’re enforceable limits under the building regulations, a set of technical standards governing safety, energy efficiency, and structural integrity in construction.

What you can’t do under permitted development? You can’t extend past the front of the house, build higher than the current roofline, or add a balcony or veranda. If your home is in a conservation area, a National Park, or is a listed building, most permitted development rights vanish. Even if you’re not in one of these areas, you still need to follow building regulations, which cover insulation, ventilation, fire safety, and structural load. A poorly insulated extension might save money upfront but cost you in energy bills and compliance fines later. Many homeowners skip the building control inspection thinking they’re safe under permitted development—only to find out during a house sale that their extension lacks certification. That’s a red flag for buyers and lenders.

Don’t assume your neighbor’s extension is legal just because it’s there. Rules change based on house type, location, and even when your house was built. A 2023 amendment to the permitted development rules in England now limits single-story extensions to 4 meters for terraced and semi-detached homes, down from 6. If you’re planning a loft conversion, you can’t add dormers that protrude beyond the roof plane, and the total volume added can’t exceed 40 cubic meters for terraced homes or 50 for detached. These numbers aren’t arbitrary—they’re based on preserving neighborhood character and preventing overshadowing.

Before you start digging or ordering materials, check your local council’s online portal. Some areas have additional restrictions called Article 4 directions that remove permitted development rights entirely. You can also apply for a Lawful Development Certificate—it’s cheap, takes a few weeks, and gives you official proof your project is allowed. This isn’t just paperwork; it’s insurance for your future home sale. Buyers’ solicitors will ask for it. If you don’t have it, you might have to pay to retroactively apply for planning permission—or worse, tear it down.

Below, you’ll find real-world guides on what’s allowed, how to avoid common mistakes, and what happens when you go over the line. From foundation rules to material limits, these posts break down the confusing parts so you don’t end up paying for someone else’s error.