Two-storey side extensions in Formby
A two-storey side extension is one of the most space-efficient ways to add bedrooms and living space to a house in Formby, because the new floors share one set of foundations and one roof.
The basics for Formby at a glance.
- Postcode districts
- L37 and L38
- 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
- Maghull (6 miles), Southport (6.5 miles), Bootle (6.7 miles)
- Distance to Liverpool
- about 10.9 miles
- First visit
- Free, no obligation
About a two-storey side extension
A two-storey side extension suits a detached or semi-detached house with a side garden, driveway or garage wide enough to build on. You get a design that sits comfortably on the street, a planning application or permitted development check depending on your nation, structural design, building regulations approval and the build itself. We manage the whole process, and the work is carried out by vetted teams working under S&K.
Around Formby we also work in Maghull, Southport and Bootle, and across the rest of Merseyside. Postcode districts in and near Formby: L37 and L38.
What it costs in Formby
In North West England, which includes Formby, we'd expect a two-storey side extension to cost around £82,000–£109,500 for a 3 m × 7 m footprint on two floors (42 m² of new floor space), or £1,950–£2,610 per m² including VAT. Professional fees for drawings and the structural engineer are listed separately on our prices page.
| 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 Formby
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 Formby homes
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.
Side windows, boundaries and gutters
Upstairs windows in the side wall face the neighbour, so they are usually obscure-glazed and fixed, or left out. Building close to the boundary also raises questions about foundations, overhanging gutters and access for maintenance, so we design the eaves and gutter to stay within your land.
How we'd run your project
Free site visit
We visit your home in Formby, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Choose the approval route
Some designs fit permitted development, most need a householder application. We decide which applies in England before drawing in detail.
Technical design
We prepare the building regulations drawings, structural calculations and specification so the build price can be fixed.
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 side extensions in Formby
Do I need planning permission for a two-storey side extension in Formby?
Formby 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.
How long does a two-storey side 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.
Which postcodes do you cover around Formby?
We cover Formby (L37 and L38) and nearby places including Maghull, Southport and Bootle, plus the rest of Merseyside. The first site visit is free.
How much does a two-storey side extension cost in Formby?
Our guide for North West England, which covers Formby, 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.
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
Other towns near Formby:
Other extensions in Formby
- 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 Formby · Two-storey side extensions across Merseyside
Want a figure first? Try our guide price tool, then book a free visit to firm it up.