Quick answer
A wraparound extension is an L-shaped extension that joins a side extension and a rear extension into one space, wrapping around the back corner of your house. In Kent in 2026, expect to pay roughly £2,400 to £3,300 per m2, which is about £72,000 to £148,000 for a typical 30 to 45 m2 build. Most wraparounds need full planning permission, building regulations approval and often a party wall agreement. Allow around 12 to 16 weeks on site once planning is approved.
That is the short version. The rest of this guide explains what drives the price, how planning works in Maidstone and across Kent, and what we have learned building this type of extension for Kent homeowners.
What is a wraparound extension?
A wraparound extension (also called an L-shaped extension) combines a rear extension with a side extension, so the new space turns the back corner of the house. It is most common on semi-detached and detached houses and on bungalows with a side passage or unused side garden.
It is different from a side return extension, which only fills the narrow strip beside a terraced house, and from a plain rear extension, which only pushes out the back. A wraparound does both at once, which is why it creates so much more usable space and why it needs more careful structural design.
How much does a wraparound extension cost in Kent?
Published 2026 UK guides put wraparound extensions at around £2,000 to £3,300 per m2 depending on specification, and note that London and the South East add roughly 20 to 30 percent. That puts Kent at the upper half of the national range. These are guide figures, not a quote, and your price will depend on the points below.
| Extension size | Typical Kent cost range (2026) | Typical use |
|---|---|---|
| 30 m2 | £72,000 to £99,000 | Larger kitchen plus dining area |
| 40 m2 | £96,000 to £132,000 | Open-plan kitchen, dining and living |
| 45 m2 | £108,000 to £148,000 | Open-plan space plus utility or study |
Ranges are estimates based on published 2026 UK cost guides with a South East uplift applied. Excludes kitchen units, appliances and professional fees unless stated in your quote.
What pushes the price up or down?
- Structural steelwork at the corner. Opening the back corner of the house needs long steel beams, and this is the main reason a wraparound costs more per m2 than a simple rear extension.
- Glazing. Two elevations of bi-fold or sliding doors can add five figures on their own.
- Drainage. Side extensions often sit over an existing drain run or manhole, which may need a build-over agreement or diversion.
- Roof type. A flat roof with rooflights is the standard and most cost-effective option. A pitched or hipped roof that matches the house costs more.
- Ground conditions. Clay soils and nearby trees across much of Kent can mean deeper foundations.
- Fees and extras. Budget for architect or designer fees, a structural engineer (typically £600 to £1,400), party wall surveyor fees (typically £700 to £1,500 per neighbour), building control and a contingency of around 10 percent.
Do you need planning permission for a wraparound extension?
In most cases, yes. A single-storey rear extension or a single-storey side extension can each be built under permitted development in the right circumstances, but a combined wraparound normally breaks the limits. For example, a side extension must be no wider than half the width of the original house, and the rear and side parts together must stay within the overall rules. Different rules apply to two-storey versions, and permitted development is restricted or removed on many houses.
In Kent, check these before you design anything:
- Conservation areas. Side extensions are not permitted development in conservation areas, and these cover the centres of places like Maidstone, Tunbridge Wells and Sevenoaks as well as many villages.
- Listed buildings. You will need listed building consent as well as planning permission.
- Article 4 directions and removed rights. Some Kent estates have permitted development removed, and many newer houses had it removed by condition when they were built.
- Protected landscapes. Parts of the county sit in the Kent Downs and High Weald National Landscapes, where councils take design and materials seriously.
The safest route is to apply for a Lawful Development Certificate if you believe your design is permitted development, or to submit a full application if not. A planning application normally takes around eight weeks once validated.
What building regulations and legal approvals apply?
Every wraparound extension needs building regulations approval, whether or not it needs planning permission. Building control will inspect the foundations, structure, drainage, insulation, fire safety and electrics. Your builder or a registered inspector will arrange this.
You may also need:
- A party wall notice if you are building on or near a boundary or digging foundations close to a neighbour’s building. Notices should be served at least two months before work starts.
- A build-over agreement from Southern Water if you are building over a public sewer.
- Structural engineer’s calculations for the steelwork at the corner opening.
What are the structural challenges of a wraparound extension?
This is where experience matters most. The back corner of a house is usually load-bearing, and taking it out to open the kitchen into the new space means supporting the floors, walls and roof above while the work is done.
In practice, our approach to the structural stage includes:
- A structural engineer designs the steel beams and padstones before any demolition starts.
- Temporary propping is installed to carry the loads while the old wall is removed and the steel goes in.
- The steel is installed and checked by building control before the wall below is taken out in full.
- The new structure is made weathertight quickly, so the rest of the build is protected from the Kent weather.
BDC has carried out structural alterations, steelwork and wall removals across hundreds of residential projects in Kent, working with trusted structural engineers, electricians, plasterers and roofers who we use project after project.
Wraparound extension vs other options: which is right for you?
| Option | Best for | Cost per m2 (Kent, estimate) | Planning |
|---|---|---|---|
| Wraparound extension | Maximum space and a big open-plan layout | £2,400 to £3,300 | Usually full planning |
| Rear extension only | Simple, lower-cost extra space | £2,000 to £2,800 | Often permitted development |
| Side return extension | Terraced houses with a narrow side strip | £2,200 to £3,000 | Varies, often needs approval |
| Double storey extension | Adding bedrooms as well as living space | £2,000 to £2,800 (per m2 of floor area) | Full planning |
Estimates only.
How long does a wraparound extension take?
Plan on 12 to 16 weeks on site for a single-storey wraparound, plus the design, planning and party wall stages beforehand. From first idea to finished kitchen, 8 to 12 months is realistic. Your existing kitchen will often be out of use for part of the build, so plan a temporary kitchen from the start. Many of our clients stay in the house throughout, and we keep the site tidy and the disruption low.
How do you choose a builder for a wraparound extension?
Ask for evidence of similar structural work, not just photos of finished kitchens. Check they will use a structural engineer, that they handle building control, and that your quote lists steelwork, drainage and glazing separately.
Thinking about a wraparound extension in Kent?
BDC Construction was founded in 2011 by Ben, who has over 20 years of hands-on building experience. We build house extensions across Maidstone, Bearsted, Headcorn, Sevenoaks, Tunbridge Wells and surrounding areas, from design through to completion. Contact BDC Construction for a free, no-obligation quote on your wraparound extension.
Frequently asked questions
How much does a wraparound extension cost in Kent?
Roughly £2,400 to £3,300 per m2 in 2026, so about £72,000 to £148,000 for a 30 to 45 m2 extension, before kitchen and professional fees.
Do you need planning permission for a wraparound extension?
Usually yes. A combined side and rear extension normally exceeds permitted development limits, and conservation areas, listed buildings and removed rights make it more likely still.
How long does a wraparound extension take to build?
Around 12 to 16 weeks on site for a single-storey build, after planning and party wall stages are complete.
Is a wraparound extension worth it?
It is usually worth it if you want a large open-plan kitchen and living space and have room at the side and rear. It costs more per m2 than a rear extension because of the corner steelwork, but it creates more usable space than either a rear or side extension alone.
Can you live in your house during a wraparound extension?
Often yes. The main disruption is the kitchen, so a temporary kitchen set-up is usually needed during the structural and fit-out stages.
What is the difference between a wraparound and an L-shaped extension?
Nothing. They are two names for the same thing: a side and rear extension joined at the back corner of the house.