Two-storey wraparound extensions in London Colney
Adding a two-storey wraparound extension in London Colney gives you two new rooms stacked on one footprint. Here's how we'd approach it, what it typically costs and the rules that apply in England.
The basics for London Colney at a glance.
- Postcode districts
- AL2
- County / area
- Hertfordshire, England
- Price region
- East of England
- Guide price
- £124,000–£170,000 (£2,210–£3,040 per m²)
- Approval route
- Planning permission is needed: the side part takes it outside permitted development in England.
- Nearest towns
- St Albans (2.4 miles), Hatfield (4.1 miles), Borehamwood (4.9 miles)
- Distance to Watford
- about 6.4 miles
- First visit
- Free, no obligation
About a two-storey wraparound extension
A two-storey wraparound extension suits a house with space both beside it and behind it, where you want to transform the layout rather than add a single room. You get one design for the whole L-shape, the planning application, structural design for the corner and the openings into the house, building regulations approval and the build, managed by us and carried out by vetted teams working under S&K.
London Colney sits about 6.4 miles from Watford. Closer to home, St Albans is 2.4 miles away and Hatfield 4.1 miles.
What it costs in London Colney
Expect a two-storey wraparound extension in London Colney to land somewhere around £124,000–£170,000 for an L-shaped footprint of about 28 m² wrapping the side and rear, on two floors (56 m² of new floor space). Our East of England guide rate is £2,210–£3,040 per m², including VAT. Steelwork for wide openings is the item most likely to move the figure; we'll know once the engineer has designed it.
| Spec | Per m² | An L-shaped footprint of about 28 m² wrapping the side and rear, on two floors (56 m² of new floor space) |
|---|---|---|
| Essential | £2,040–£2,800 per m² | £114,000–£156,500 |
| Standard | £2,210–£3,040 per m² | £124,000–£170,000 |
| Premium | £2,660–£3,650 per m² | £149,000–£204,000 |
Planning and building regulations in London Colney
In England, a two-storey wraparound extension needs householder planning permission, because any extension beyond a side wall must be single storey to be permitted development. The application costs £548 (or £575 for applications made from 8 December 2026). Councils weigh the side part against the street scene and the rear part against neighbours' light and outlook, and should decide within 8 weeks of validation.
Approval in England: Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.
Building regulations: Building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end.
Design points for London Colney homes
The corner post
At the outside corner of the L, there is no existing wall to carry the floor above. Opening the ground floor fully usually means a steel frame or a corner post, and the engineer's design sets how slim it can be. We decide early whether you want a clear corner or a visible post.
Daylight to the middle
A deep L-shaped plan can leave the middle of the ground floor dark, because the old rear rooms are now enclosed. We use wide rear openings, a well-placed stair and, where part of the extension is single storey, roof lights, while keeping total glazing within the Part L allowance.
How we'd run your project
Measure and listen
A visit to London Colney to understand how you live in the house now and what the extra rooms need to do, plus a first look at the structure.
Drawings, then consent
We draw the scheme, check it against the rules in England, and take it through the right consent with the council.
Engineer it
Foundations sized for two floors, steels for any openings, and building control approval, all before anyone starts on site.
Finish and certify
Second fix, plastering and making good, then building control's final inspection and the completion paperwork.
Questions about two-storey wraparound extensions in London Colney
How long does a two-storey wraparound extension take?
Allow 4 to 8 weeks for survey and design, then the approval period (councils should decide householder applications within 8 weeks of validation), then 4 to 8 weeks of technical design, which can overlap. The build itself usually takes 14 to 20 weeks, longer for large or complex designs.
Do I need planning permission for a two-storey wraparound extension in London Colney?
London Colney is in England, so England planning rules apply. Planning permission is needed: the side part takes it outside permitted development in England. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.
How much does a two-storey wraparound extension cost in London Colney?
Our guide for the East of England, which covers London Colney, is £2,210–£3,040 per m² including VAT. A typical project with an L-shaped footprint of about 28 m² wrapping the side and rear, on two floors (56 m² of new floor space) comes to about £124,000–£170,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.
Can I stay at home during a wraparound extension?
Many people do, but a wraparound affects two sides of the house and usually the kitchen, so there will be weeks without a full kitchen. We plan a temporary kitchen, keep a route through the house and seal off the work area. For some families, moving out while the rear wall is opened up is easier.
Does a wraparound extension need steel?
Almost always. Opening the corner of the house and the old rear wall to make one open-plan space means steel beams, and often a steel post or frame at the outside corner. The structural engineer sizes these, and the steel is ordered once the design is fixed, which is one reason a wraparound needs careful sequencing.
Nearby
Close to London Colney? We work across the area, including:
Other extensions in London Colney
- Rear
- Side
- Part two-storey
- Over a garage
- First floor
- Semi-detached
- Detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in London Colney · Two-storey wraparound extensions across Hertfordshire
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