Two-storey extensions for semi-detached houses in Fareham
Adding a two-storey extension for a semi-detached house in Fareham 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.
What we'd confirm first for a project in Fareham.
- Postcode districts
- PO14, PO15, PO16 and PO17
- County / area
- Hampshire, 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
- Gosport (4.5 miles), Cosham (5.1 miles), Portsmouth (5.3 miles)
- Distance to Southampton
- about 10.5 miles
- First visit
- Free, no obligation
About a two-storey extension for a semi-detached house
This service suits you if you own a semi-detached house and want to add bedrooms and living space without moving. On a semi, the main questions are which side to build on and how to treat the attached neighbour. You get a survey, design options, the approvals your nation needs and the build, carried out by vetted teams working under S&K.
We cover Fareham (PO14, PO15, PO16 and PO17) and the places around it, including Gosport (4.5 miles), Cosham (5.1 miles) and Portsmouth.
What it costs in Fareham
Most of the cost of a two-storey extension for a semi-detached house is set by its size and specification. For Fareham and the rest of South East England, our guide is £2,200–£2,970 per m² including VAT, so about £61,500–£83,000 for a 4 m × 3.5 m footprint on two floors (28 m² of new floor space). These are guides, not quotes. Ground conditions, steelwork and access can move the figure either way.
| 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 Fareham
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 Fareham homes
Keeping the pair balanced
Semis are designed as matching pairs, and a side extension changes that balance. Setting the side extension back from the front wall and keeping its ridge lower helps the pair still read as a pair, which councils' design guides commonly ask for.
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.
How we'd run your project
Understand the brief
At your home in Fareham we agree what you need: bedroom count, bathroom, kitchen space, and how much garden you want to keep.
Get it approved
Once you're happy with the design we submit it to the council for Fareham and deal with any questions from the planning officer.
Detail and price
Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.
On site
One project lead runs the job, keeps you updated and arranges inspections at each stage until completion.
Questions about two-storey extensions for semi-detached houses in Fareham
How much does a two-storey extension for a semi-detached house cost in Fareham?
Our guide for South East England, which covers Fareham, 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.
Do I need planning permission for a two-storey extension for a semi-detached house in Fareham?
Fareham 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.
Who handles building regulations for a project in Fareham?
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.
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.
Does a two-storey extension add value to a semi-detached house?
It usually adds value, but the gain is never certain. Nationwide's 2025 research found that 10% more floor area was linked to about 5% higher value, and that adding a double bedroom and bathroom to a three-bed, one-bathroom house could add up to 24%. Every street has a ceiling price, so check local sales first.
Nearby
The same service in neighbouring towns:
Other extensions in Fareham
- 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 Fareham · Two-storey extensions for semi-detached houses across Hampshire
Tell us about your house in Fareham and we'll call you back to arrange a free, no-obligation visit.