Two-storey side extensions in Cowes
Adding a two-storey side extension in Cowes 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.
Cowes is outside our usual mainland visit area, so visits and projects here are by arrangement. We'll agree any travel costs with you before anything is booked.
Before you start in Cowes, here's what applies.
- Postcode districts
- PO31
- County / area
- The Isle of Wight, England
- Price region
- South East England
- Guide price
- £94,500–£127,000 (£2,260–£3,030 per m²)
- Approval route
- Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
- Nearest towns
- East Cowes (0.5 miles), Newport (Isle of Wight) (4.2 miles), Ryde (6.3 miles)
- Distance to Newport (Isle of Wight)
- about 4.2 miles
- First visit
- By arrangement
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 Cowes (PO31) and the places around it, including East Cowes (0.5 miles), Newport (Isle of Wight) (4.2 miles) and Ryde.
What it costs in Cowes
For budgeting in Cowes, allow around £94,500–£127,000 for a two-storey side extension with a 3 m × 7 m footprint on two floors (42 m² of new floor space). That's based on £2,260–£3,030 per m² including VAT for South East England. Keep a contingency of around 10% for things nobody can see until the ground is opened up.
| 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 Cowes
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 Cowes homes
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.
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 by arrangement
We agree a visit to your home in Cowes and any travel costs with you in writing first, then look at the structure, access and boundaries.
Get it approved
Once you're happy with the design we submit it to the council for Cowes and deal with any questions from the planning officer.
Structure and building control
A structural engineer sizes the foundations and steels, and we get building regulations approval before work starts.
Build it
The new structure goes up first, then we open into the house, finish inside and get the completion certificate.
Questions about two-storey side extensions in Cowes
Do I need planning permission for a two-storey side extension in Cowes?
Cowes 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 much does a two-storey side extension cost in Cowes?
Our guide for South East England, which covers Cowes, 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.
Who handles building regulations for a project in Cowes?
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.
Which postcodes do you cover around Cowes?
We cover Cowes (PO31) and nearby places including East Cowes, Newport (Isle of Wight) and Ryde, plus the rest of the Isle of Wight. Visits and projects in Cowes are by arrangement, with travel costs agreed in writing first.
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 site visit before any drawings are prepared.
Nearby
Nearby towns we cover for two-storey side extensions:
Other extensions in Cowes
- 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 Cowes · Two-storey side extensions across the Isle of Wight
Send us your postcode and a few details. We'll get back to you to arrange a visit and talk through your options.