Two-storey side extensions in West Derby
Our two-storey side extensions service in West Derby covers everything: measured survey, design, planning or permitted development checks, structural design, building control and the build itself.
The basics for West Derby at a glance.
- Postcode districts
- L12
- County / area
- Merseyside, England
- Price region
- North West England
- Guide price
- £82,000–£109,500 (£1,950–£2,610 per m²)
- Approval route
- Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
- Nearest towns
- Norris Green (1 mile), Knotty Ash (1.3 miles), Croxteth (1.3 miles)
- Distance to Liverpool
- about 3.2 miles
- First visit
- Free, no obligation
About a two-storey side extension
A two-storey side extension is a new two-floor addition built into the space beside your house, often over a driveway or side passage. It typically adds one or two bedrooms upstairs and a utility, study or larger kitchen below, without giving up rear garden.
We cover postcode district L12 in and around West Derby, along with neighbouring Norris Green, Knotty Ash and Croxteth.
What it costs in West Derby
A guide price for West Derby: around £82,000–£109,500 for a 3 m × 7 m footprint on two floors (42 m² of new floor space). That works out at £1,950–£2,610 per m² of new floor space, including VAT at 20%. 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 | £1,790–£2,400 per m² | £75,500–£101,000 |
| Standard | £1,950–£2,610 per m² | £82,000–£109,500 |
| Premium | £2,340–£3,130 per m² | £98,000–£131,500 |
Planning and building regulations in West Derby
In England, a two-storey side extension always needs householder planning permission, because permitted development only allows single-storey extensions beyond a side wall. The fee is £548 (or £575 for applications made from 8 December 2026), and councils should decide within 8 weeks of validation. Expect them to look at set-back, roof height, gaps to the boundary and the effect on neighbours.
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 West Derby homes
Matching the ridge and roof
A hipped house usually needs a hipped extension roof, and a gabled house a gable. Matching the pitch, tiles, ridge detail and brick bond is what makes a side extension look original rather than added, and councils look closely at it on a front-facing addition.
Avoiding a terracing effect
Where semi-detached houses sit close together, side extensions on neighbouring houses can join up and turn a row of pairs into a terrace. Many councils ask for a gap to the boundary at first floor to stop this, so we check local guidance before fixing the width.
How we'd run your project
Visit and first ideas
One of our team visits your house in West Derby, checks the walls, roof and drains, and sketches out options with you.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Structure and building control
A structural engineer sizes the foundations and steels, and we get building regulations approval before work starts.
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 side extensions in West Derby
How much does a two-storey side extension cost in West Derby?
Our guide for North West England, which covers West Derby, is £1,950–£2,610 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 £82,000–£109,500. 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 West Derby?
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 side extension in West Derby?
West Derby is in England, so England planning rules apply. Planning permission is needed: in England, permitted development only allows single-storey extensions to the side. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.
Which postcodes do you cover around West Derby?
We cover West Derby (L12) and nearby places including Norris Green, Knotty Ash and Croxteth, plus the rest of Merseyside. The first site visit is free.
Can I build a two-storey side extension over my driveway?
Yes, if the drive is wide enough for a useful room and the council accepts the design. You may lose off-road parking, which some councils weigh up, and the foundations need to suit the ground below. We check parking, drains and meter positions at the free site visit before any drawings are prepared.
Nearby
We also cover places near West Derby, including:
Other extensions in West Derby
- Rear
- Wraparound
- Part two-storey
- Over a garage
- First floor
- Semi-detached
- Detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in West Derby · Two-storey side extensions across Merseyside
Ready to talk it through? Call us or send the form and we'll arrange a visit to your home in West Derby.