Wrap-around extensions: what they are, the rules and how one is built

What is a wrap-around extension?

A wrap-around extension is a side extension and a rear extension built as one, so the new space turns the corner of the house in an L shape. On many semi-detached and detached houses the strip down the side is a path, a side return or a narrow garage, and the back is a kitchen with a door to the garden. A wrap-around takes in both, usually to make one larger kitchen, dining and living area on the ground floor.

It can be single-storey, or have a second storey over part of it, and it can be built at the same time as other work on the house. Brick2Brick UK’s 2025 wrap-around in Bromsgrove came with a loft conversion.

Why do people choose a wrap-around?

Mostly for floor space in one go. Building the side and the back together means one set of footings, one roof to tie in and one spell of disruption, rather than two separate projects years apart. It also lets a kitchen run into the side return, which a rear extension on its own cannot do.

The trade-off is that a wrap-around touches more of the house. Walls come out on two sides, so steels are usually needed to carry the floors and roof above, and the planning rules are tighter than for a simple rear extension.

Can a wrap-around extension be built under permitted development?

Permitted development rights let you extend a house without a planning application if the work stays inside set limits. The government’s technical guidance deals with wrap-arounds directly: where an extension fills the area between a side wall and the rear wall, the limits for rear extensions and for side extensions both apply. To count as permitted development, the guidance says the extension must:

• be single-storey and no more than 4 metres high
• have a total width of no more than half the width of the original house, measured at its widest point
• go no more than 6 metres beyond the rear wall, or 8 metres for a detached house; anything beyond 3 metres (4 metres for a detached house) needs prior approval first, and on designated land the limit stays at 3 metres (4 metres detached)

So does a wrap-around need planning permission?

Usually, yes. The width rule is the one that decides it. The technical guidance shows examples of extensions that go beyond a side wall and are more than half the width of the original house, and says each of them needs an application for planning permission. A wrap-around that runs across the whole back of the house and down the side is wider than the house itself, so it cannot meet that rule.

The Planning Portal adds three more points. Any side extension of more than one storey needs householder planning permission. On designated land (a conservation area, a National Park, an Area of Outstanding Natural Beauty, the Broads or a World Heritage Site) every side extension needs it. And the limits count any earlier extensions to the house, while some houses have lost their permitted development rights through an Article 4 direction or a planning condition.

So for a full wrap-around, plan on a householder planning application and check with your council before you settle on a design. The planning permission guide sets out the limits for rear, side and two-storey extensions in more detail.

Does a wrap-around need building regulations approval?

Expect it to. The Planning Portal says most extensions need approval under the building regulations, and lists the parts usually checked on an extension: foundations, floors, walls below ground level, ventilation, energy efficiency and structural openings, along with doors and windows, drainage, electrics, walls and roofs. Building regulations approval is separate from planning permission, and you might need both.

You apply to a building control body: your local council or a private registered building control approver. gov.uk describes two main routes. A full plans application is the most thorough, with a decision expected within 5 weeks, or 2 months with your consent, and a completion certificate usually within 8 weeks of the work finishing, as long as it complies. A building notice is only for smaller projects: work can start 2 days after it is submitted, but there is no formal approval of plans.

gov.uk also warns that without approval you will not have the certificates of compliance you may need when you sell your home. If the extension is close to a neighbour’s house or on the boundary, the Party Wall etc. Act 1996 may apply as well.

How is a wrap-around built? The Bromsgrove job, stage by stage

Brick2Brick UK built its Bromsgrove wrap-around in summer 2025. The job included a loft conversion, so the work on the roof ran alongside the ground-floor build. The main stages:

• 7 July 2025: the new walls up, and the work moving into the existing house.
• 8 July 2025: roof off and steels in, with the roof stripped, red steel beams in place and scaffold round the house.
• 22 July 2025: the loft conversion under way, with a new dormer at the back.
• 13 August 2025: the windows going in, with the scaffold due down the next day and work on the lower roofs carrying on.

What comes before the walls go up?

The Bromsgrove job ran from May to August 2025, when the windows went in. The early stages are the same on every extension. On other Brick2Brick UK jobs they ran in this order:

• Footings dug out, a grab lorry in to clear the spoil, then concrete (September 2026).
• Walls built up to the damp proof course, then the floor slab, then the main walls. On a 2023 extension the walls went up to DPC on a Thursday, the floor was concreted on the Saturday and the main structure was built on the Tuesday and Wednesday after.
• Walls up to wall plate, steels in where existing walls are opened up, then the roof. On a Longbridge extension in 2026 the steels went in ready for the roof to start the following Monday.
• Windows in, scaffold down, then the inside: plastering, floors and decorating.

What should you ask a builder about a wrap-around?

Citizens Advice suggests getting written quotes, checking insurance and asking for references before choosing anyone. For a wrap-around, these questions are worth asking too:

• Is the price a written quote or an estimate? Citizens Advice points out that a quote is a fixed price and an estimate is a rough guess.
• Who checks the planning position, and who applies for building regulations approval?
• Who provides the structural calculations for the steels?
• Does the Party Wall Act apply, and when do the notices need to go out?
• How often will you update me, and who is on site day to day?
• Can I see your insurance? Brick2Brick UK is insured up to £10 million.
• Can I see jobs like mine? Citizens Advice suggests asking for 2 or 3 recent examples of similar work.

See the build

The full build story, with photos and drone footage, is on the Bromsgrove wrap-around extension page. For other kinds of extension, see extensions by Brick2Brick UK.

Questions