Part single, part two-storey extensions in West Molesey
Adding a part single, part two-storey extension in West Molesey 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.
Useful details for planning a part single, part two-storey extension in West Molesey.
- Postcode districts
- KT8
- County / area
- Surrey, England
- Price region
- South East England
- Guide price
- £79,000–£109,000 (£2,200–£3,030 per m²)
- Approval route
- It may be permitted development if it goes no more than 3 m beyond the original rear wall (counting any single-storey part) and stays 7 m from the rear boundary; otherwise it needs planning permission.
- Nearest towns
- Hampton (1.1 miles), East Molesey (1.3 miles), Sunbury-on-Thames (1.7 miles)
- Distance to Woking
- about 9.5 miles
- First visit
- Free, no obligation
About a part single, part two-storey extension
A part single, part two-storey extension is an extension where the ground floor is wider or deeper than the floor above, so only part of it rises to two storeys. It usually gives a large kitchen or living area with roof lights below and one bedroom or bathroom above. It is often a good way to add space while limiting the effect on neighbours.
West Molesey sits about 9.5 miles from Woking. Closer to home, Hampton is 1.1 miles away and East Molesey 1.3 miles.
What it costs in West Molesey
A guide price for West Molesey: around £79,000–£109,000 for a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total). That works out at £2,200–£3,030 per m² of new floor space, including VAT at 20%. These are guides, not quotes. Ground conditions, steelwork and access can move the figure either way.
| Spec | Per m² | A 6 m × 4 m ground floor and a first floor over half of it (36 m² in total) |
|---|---|---|
| Essential | £2,020–£2,780 per m² | £73,000–£100,000 |
| Standard | £2,200–£3,030 per m² | £79,000–£109,000 |
| Premium | £2,640–£3,630 per m² | £95,000–£130,500 |
Planning and building regulations in West Molesey
In England, the extension can only be permitted development if it goes no more than 3 m beyond the original rear wall and stays at least 7 m from the rear boundary, with matching materials and roof pitch. We check the whole design against the rules, including the 50% garden coverage limit. If any part fails, or extends beyond a side wall on two floors, you need planning permission, costing £548 (or £575 for applications made from 8 December 2026).
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 Molesey homes
The roof junction
Where the single-storey roof meets the two-storey wall you need a sound weathering detail, usually a lead or similar flashing, and enough height for roof lights or a lantern. We set the roof falls and the upstairs window sill heights together so they do not clash.
Where to put the two-storey part
The two-storey section usually works best away from the closest neighbour, with the single-storey part on that boundary side. We test a few positions against neighbours' windows, the upstairs layout and the roof shape before choosing the one to take forward.
How we'd run your project
Visit and first ideas
One of our team visits your house in West Molesey, checks the walls, roof and drains, and sketches out options with you.
Drawings and permission
Our designers produce plans and elevations, then we take care of planning or permitted development checks with the council covering West Molesey.
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 part single, part two-storey extensions in West Molesey
How much does a part single, part two-storey extension cost in West Molesey?
Our guide for South East England, which covers West Molesey, is £2,200–£3,030 per m² including VAT. A typical project with a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total) comes to about £79,000–£109,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.
Which postcodes do you cover around West Molesey?
We cover West Molesey (KT8) and nearby places including Hampton, East Molesey and Sunbury-on-Thames, plus the rest of Surrey. The first site visit is free.
Do I need planning permission for a part single, part two-storey extension in West Molesey?
West Molesey is in England, so England planning rules apply. It may be permitted development if it goes no more than 3 m beyond the original rear wall (counting any single-storey part) and stays 7 m from the rear boundary; otherwise it needs planning permission. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.
Can I add roof lights to the single-storey part?
Yes. Roof lights or a lantern over the single-storey part are one of the main reasons to choose this design, as they light the middle of a deep kitchen. In England they count towards the Part L glazing allowance, normally 25% of the new floor area plus windows removed, so we balance them with the rear doors.
Can the single-storey part be deeper than the two-storey part?
With planning permission, yes, and that is often the point of the design: the ground floor projects further into the garden while the first floor stays back from neighbours. Under permitted development, the depth limits for extensions of more than one storey can apply to the whole extension, so we confirm which route applies before drawings are finalised.
Nearby
Close to West Molesey? We work across the area, including:
Other extensions in West Molesey
- Rear
- Side
- Wraparound
- Over a garage
- First floor
- Semi-detached
- Detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in West Molesey · Part single, part two-storey extensions across Surrey
Send us your postcode and a few details. We'll get back to you to arrange a visit and talk through your options.