Part single, part two-storey extensions in Chessington

Chessington: the key facts for this kind of project.

Postcode districts: KT9
County / area: Greater London, England
Price region: London
Guide price: £86,500–£119,000 (£2,400–£3,300 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: Hook (0.4 miles), Tolworth (1.6 miles), Surbiton (2 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.

We cover postcode district KT9 in and around Chessington, along with neighbouring Hook, Tolworth and Surbiton.

What it costs in Chessington

Our guide for London is £2,400–£3,300 per m² including VAT. On a project with a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total), that puts a part single, part two-storey extension in Chessington at roughly £86,500–£119,000. Design fees, structural calculations and approval fees are separate and listed on our prices page.

Spec	Per m²	A 6 m × 4 m ground floor and a first floor over half of it (36 m² in total)
Essential	£2,210–£3,040 per m²	£79,500–£109,500
Standard	£2,400–£3,300 per m²	£86,500–£119,000
Premium	£2,880–£3,960 per m²	£103,500–£142,500

Planning and building regulations in Chessington

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 Chessington homes

Light into the kitchen

The single-storey part is the place for roof lights or a lantern, which bring daylight deep into the plan. In England, glazing is normally limited to 25% of the new floor area plus any windows removed, unless calculations show the house still performs, so we plan the balance early.

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

Understand the brief
At your home in Chessington 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 Chessington and deal with any questions from the planning officer.
Fixed price in writing
With approved drawings and calculations, we give you a fixed build price and a programme you can plan around.
Finish and certify
Second fix, plastering and making good, then building control's final inspection and the completion paperwork.

Questions about part single, part two-storey extensions in Chessington

Do I need planning permission for a part single, part two-storey extension in Chessington?

Chessington 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.

Who handles building regulations for a project in Chessington?

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.

How much does a part single, part two-storey extension cost in Chessington?

Our guide for London, which covers Chessington, is £2,400–£3,300 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 £86,500–£119,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

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

Nearby towns we cover for part single, part two-storey extensions:

Other extensions in Chessington

All two-storey extension services in Chessington · Part single, part two-storey extensions across Greater London

Book a free site visit in Chessington and we'll tell you what's possible, what approvals you need and what the design stage would cost.