Two-storey extensions for detached houses in Peacehaven
Adding a two-storey extension for a detached house in Peacehaven 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.
Before you start in Peacehaven, here's what applies.
- Postcode districts
- BN10
- County / area
- East Sussex, England
- Price region
- South East England
- Guide price
- £94,500–£127,000 (£2,260–£3,030 per m²)
- Approval route
- Depends on position: a two-storey rear extension may be permitted development (3 m deep, 7 m from the rear boundary); a two-storey side extension needs planning permission.
- Nearest towns
- Rottingdean (2.6 miles), Newhaven (2.7 miles), Seaford (5 miles)
- Distance to Brighton
- about 6.3 miles
- First visit
- Free, no obligation
About a two-storey extension for a detached house
This service suits you if you own a detached house and want a substantial amount of extra space, whether a side extension over a drive, a rear extension into the garden or a wraparound. You get a survey of the whole plot, options that compare layouts and costs, the approvals your nation needs, structural design and the build, carried out by vetted teams working under S&K.
We cover postcode district BN10 in and around Peacehaven, along with neighbouring Rottingdean, Newhaven and Seaford.
What it costs in Peacehaven
Guide prices for two-storey extensions for detached houses in South East England are around £2,260–£3,030 per m² of new floor space, including VAT. For a typical project with a 3 m × 7 m footprint on two floors (42 m² of new floor space), that's roughly £94,500–£127,000. We'll give you a written design-stage price first, then a fixed build price once the drawings are agreed.
| Spec | Per m² | A 3 m × 7 m footprint on two floors (42 m² of new floor space) |
|---|---|---|
| Essential | £2,070–£2,780 per m² | £87,000–£117,000 |
| Standard | £2,260–£3,030 per m² | £94,500–£127,000 |
| Premium | £2,710–£3,630 per m² | £113,500–£152,500 |
Planning and building regulations in Peacehaven
In England, a two-storey rear extension on a detached house can be permitted development within 3 m of the original rear wall and at least 7 m from the rear boundary, with matching roof pitch and materials, outside protected areas. Any two-storey side or wraparound extension needs planning permission, costing £548 (or £575 for applications made from 8 December 2026), with a decision due 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 Peacehaven homes
Larger spans and steelwork
Bigger extensions often mean wider openings and longer spans, which need more steel and sometimes a steel frame. The engineer designs these early, because the size of the steel affects ceiling heights, floor depths and the cost.
Choosing the best side
On a detached house you can often extend on either side or the rear. We look at orientation for daylight, where the stairs and landing are, the distance to each boundary, drains and trees, so the extension goes where it adds the most useful space.
How we'd run your project
Start at your house
We come to your home in Peacehaven, measure up, check the ground floor walls and roof structure, and note anything near the boundaries.
Design and approvals
We draw the extension and check it against the rules for England, then apply for planning permission or a certificate of lawfulness, whichever fits.
Price it properly
Once the engineer's calculations are in, we fix the build price in writing, with a clear list of what's included.
Build
Foundations, walls, floor, roof, windows, then first and second fix. We break through into the house as late as we can.
Questions about two-storey extensions for detached houses in Peacehaven
Do I need planning permission for a two-storey extension for a detached house in Peacehaven?
Peacehaven is in England, so England planning rules apply. Depends on position: a two-storey rear extension may be permitted development (3 m deep, 7 m from the rear boundary); a two-storey side extension needs planning permission. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.
How long does a two-storey extension for a detached house 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.
How much does a two-storey extension for a detached house cost in Peacehaven?
Our guide for South East England, which covers Peacehaven, is £2,260–£3,030 per m² including VAT. A typical project with a 3 m × 7 m footprint on two floors (42 m² of new floor space) comes to about £94,500–£127,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.
Is a detached house extension a better investment than moving?
It often costs less than the gap between your house and a larger one nearby, once property tax, legal fees and removal costs are counted, but that depends on your area. Extending also has limits: every street has a ceiling price. We give you build costs so you can compare them with local asking prices.
Can I extend a detached house on both sides?
Sometimes. With planning permission, a council may accept extensions on both sides if the house stays well proportioned and keeps gaps to the boundaries. It is more common to extend on one side and the rear, or with a wraparound. We look at the plot as a whole before suggesting more than one extension.
Nearby
Close to Peacehaven? We work across the area, including:
Other extensions in Peacehaven
- Rear
- Side
- Wraparound
- Part two-storey
- Over a garage
- First floor
- Semi-detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in Peacehaven · Two-storey extensions for detached houses across East Sussex
Send us your postcode and a few details. We'll get back to you to arrange a visit and talk through your options.