What is a wraparound extension?
A wraparound extension combines a side return and a rear extension into one L-shaped addition. It gives the largest possible ground floor, often creating an open-plan kitchen, dining and living space across the whole width of the house.
How much does a wraparound extension cost in Welwyn Garden City?
In Welwyn Garden City, a wraparound extension typically costs £2,350–£3,400 per m² of floor area, including VAT at 20% (standard rate). For a typical 28 m² project that is roughly £66,000–£95,000. Building costs in the East of England run about 6% above the UK average, and the figures for Welwyn Garden City are adjusted to reflect that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (20 m²) | £47,000–£68,000 |
| Typical project (28 m²) | £66,000–£95,000 |
| Larger project (39 m²) | £91,500–£132,500 |
| Rate per m² | £2,350–£3,400 |
The main things that change the cost:
- Steelwork and propping of the existing house
- Total footprint and the amount of glazing
- Drainage changes
- Kitchen and flooring specification
A guide range is only a starting point: the guide price tool gives an instant figure for your size, and a free survey turns it into a fixed quote.
Do you need planning permission for a wraparound extension in Welwyn Garden City?
Approvals for a wraparound extension in Welwyn Garden City follow the rules for England. In England a wraparound extension combines side and rear elements, which normally takes it outside permitted development, so a householder planning application is made.
Building regulations approval comes from the council’s building control service or a registered building control approver. The work is inspected at key stages, such as foundations, drainage and insulation, and a completion certificate is issued at the end.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
Handled as part of most wraparound extensions:
- Party wall notices and surveyor liaison
- Design and planning application
- Removal of internal and external walls
- Structural engineer’s design for steels and supports
- Walls, roof and glazing
- Underfloor heating option, electrics and plastering
How long does it take?
Build time is typically 12 to 18 weeks on site. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Welwyn Garden City
Many towns in the East of England have estates built since the 1970s, where garage conversions and rear extensions are popular.
Our Welwyn Garden City coverage includes postcode districts AL8, and we also work in nearby places such as Hatfield, Hertford and St Albans.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about wraparound extensions in Welwyn Garden City
What about the old back addition?
The side wall of the back addition is usually removed and replaced with a steel beam, so the old kitchen joins the new space.
Do you build wraparound extensions in Welwyn Garden City?
Yes. We build wraparound extensions across Welwyn Garden City, including postcodes AL8. Every project starts with a free home visit.
Can we keep a separate living room?
Yes. Many clients keep the front room separate and open up only the back of the house.
Is a wraparound worth it?
It gives the biggest ground-floor space without going upwards. Whether it adds value depends on your street and house, so we suggest checking local sale prices before committing.
How much does a wraparound extension cost in Welwyn Garden City?
In Welwyn Garden City, a wraparound extension typically costs £2,350–£3,400 per m² of floor area, including VAT at 20% (standard rate). A typical 28 m² project comes to roughly £66,000–£95,000. Your fixed price depends on the survey and drawings.