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 Harpenden?
In Harpenden, 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. That range is adjusted for the East of England, where domestic building work typically costs around 6% above the national average. 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 biggest cost drivers are:
- Party wall surveyor fees for one or both neighbours
- Access for materials on terraced streets
- 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 Harpenden?
The approval route for Harpenden is set by planning law in 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.
Where work involves a shared wall, building on the boundary, or digging foundations within 3 metres of a neighbour’s building and deeper than its foundations (or within 6 metres for deeper work), the Party Wall etc. Act 1996 applies and notices must be served before work starts.
We check this for your address before design work starts, so there are no surprises later.
What we handle
On a typical wraparound extension we handle:
- Building control completion
- Underfloor heating option, electrics and plastering
- Walls, roof and glazing
- Party wall notices and surveyor liaison
- Design and planning application
- Foundations and drainage
How long does it take?
Allow 12 to 18 weeks on site. Design and approvals come first and typically take 3 to 4 months, depending on the approval route.
Building in Harpenden
Many towns in the East of England have estates built since the 1970s, where garage conversions and rear extensions are popular.
From AL5 outwards, we take on projects throughout Harpenden and the surrounding parts of Hertfordshire.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about wraparound extensions in Harpenden
Who approves a wraparound extension in Harpenden?
Planning matters in Harpenden go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
How much does a wraparound extension cost in Harpenden?
In Harpenden, 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.
Will both neighbours be affected?
Usually only the neighbour on the side return side, but rear foundations near either boundary can trigger party wall notices.
Can we keep a separate living room?
Yes. Many clients keep the front room separate and open up only the back of the house.
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.