Two-storey extensions for semi-detached houses in Sittingbourne
Adding a two-storey extension for a semi-detached house in Sittingbourne 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.
Sittingbourne: the key facts for this kind of project.
- Postcode districts
- ME9 and ME10
- County / area
- Kent, England
- Price region
- South East England
- Guide price
- £61,500–£83,000 (£2,200–£2,970 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
- Faversham (7 miles), Sheerness (7 miles), Gillingham (8.6 miles)
- Distance to Maidstone
- about 10.7 miles
- First visit
- Free, no obligation
About a two-storey extension for a semi-detached house
A two-storey extension for a semi-detached house is a two-floor addition to the rear, the open side, or both, designed around the attached neighbour on one side. The rear is often the simplest option and can sometimes be permitted development, while a side extension uses the gap on the detached side. Both need care with the shared party wall and the neighbour's light.
Sittingbourne sits about 10.7 miles from Maidstone. Closer to home, Faversham is 7.0 miles away and Sheerness 7.0 miles.
What it costs in Sittingbourne
Guide prices for two-storey extensions for semi-detached houses in South East England are around £2,200–£2,970 per m² of new floor space, including VAT. For a typical project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space), that's roughly £61,500–£83,000. Design fees, structural calculations and approval fees are separate and listed on our prices page.
| Spec | Per m² | A 4 m × 3.5 m footprint on two floors (28 m² of new floor space) |
|---|---|---|
| Essential | £2,020–£2,730 per m² | £56,500–£76,500 |
| Standard | £2,200–£2,970 per m² | £61,500–£83,000 |
| Premium | £2,640–£3,560 per m² | £74,000–£100,000 |
Planning and building regulations in Sittingbourne
In England, a two-storey rear extension on a semi can be permitted development if it goes no more than 3 m beyond the original rear wall and stays 7 m from the rear boundary, with matching materials and roof pitch. A two-storey side or wraparound extension always needs planning permission, costing £548 (or £575 for applications made from 8 December 2026). Protected areas such as conservation areas exclude two-storey rear permitted development.
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 Sittingbourne homes
Rear, side or both
On a semi, a rear extension sits against the attached neighbour, while a side extension faces the detached neighbour and the street. We compare the space, cost and approval route for each, and for a wraparound, before you commit to one design.
The attached neighbour's light
A two-storey rear extension next to the party wall can take light from the neighbour's rear windows. Councils often use a 45-degree test, so the first floor may need to be shorter than the ground floor or set in from the shared boundary.
How we'd run your project
Look at the house
We start in Sittingbourne with a free visit: measurements, photos, a look at the loft and drains, and a frank chat about budget.
Drawings and permission
Our designers produce plans and elevations, then we take care of planning or permitted development checks with the council covering Sittingbourne.
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 and sign-off
Vetted teams working under S&K build the extension, and we arrange the building control completion certificate at the end.
Questions about two-storey extensions for semi-detached houses in Sittingbourne
How much does a two-storey extension for a semi-detached house cost in Sittingbourne?
Our guide for South East England, which covers Sittingbourne, is £2,200–£2,970 per m² including VAT. A typical project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space) comes to about £61,500–£83,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.
Who handles building regulations for a project in Sittingbourne?
We handle it as part of the project. What's needed in England: building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end. We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.
Do I need planning permission for a two-storey extension for a semi-detached house in Sittingbourne?
Sittingbourne 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.
Will a side extension make my semi look like a terrace?
It can if it fills the whole gap to the boundary at first floor and the neighbour does the same. Many councils ask for a first-floor gap to the side boundary or a set-back for this reason. We design the extension to keep the semi reading as one of a pair.
Should I extend my semi to the side or the rear?
It depends on your plot and what you need. A rear extension keeps the side drive and can sometimes be permitted development, but it affects the attached neighbour. A side extension keeps the rear garden but always needs planning permission in England. We compare both at the free site visit.
Nearby
The same service in neighbouring towns:
Other extensions in Sittingbourne
- Rear
- Side
- Wraparound
- Part two-storey
- Over a garage
- First floor
- Detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in Sittingbourne · Two-storey extensions for semi-detached houses across Kent
Tell us about your house in Sittingbourne and we'll call you back to arrange a free, no-obligation visit.