Part single, part two-storey extensions in Liverpool

Quick reference for homeowners in Liverpool.

Postcode districts: L1, L2, L3, L69 and L70
County / area: Merseyside, England
Price region: North West England
Guide price: £68,500–£94,000 (£1,900–£2,610 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: Kensington (1 mile), Kirkdale (1.6 miles), Birkenhead (1.9 miles)
First visit: Free, no obligation

About a part single, part two-storey extension

A part single, part two-storey extension suits you if you want a generous ground floor but only need one extra room upstairs, or if a full two-storey design would affect a neighbour too much. You get design options that test where the two-storey part works best, the approvals your nation needs, structural design, building regulations approval and the build, carried out by vetted teams working under S&K.

Around Liverpool we also work in Kensington, Kirkdale and Birkenhead, and across the rest of Merseyside. Postcode districts in and near Liverpool: L1, L2, L3, L69 and L70.

What it costs in Liverpool

Most of the cost of a part single, part two-storey extension is set by its size and specification. For Liverpool and the rest of North West England, our guide is £1,900–£2,610 per m² including VAT, so about £68,500–£94,000 for a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total). Kitchens, bathroom fittings and flooring are priced separately so you can compare like with like.

Spec	Per m²	A 6 m × 4 m ground floor and a first floor over half of it (36 m² in total)
Essential	£1,750–£2,400 per m²	£63,000–£86,500
Standard	£1,900–£2,610 per m²	£68,500–£94,000
Premium	£2,280–£3,130 per m²	£82,000–£113,000

Planning and building regulations in Liverpool

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 Liverpool 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.

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.

How we'd run your project

Look at the house
We start in Liverpool with a free visit: measurements, photos, a look at the loft and drains, and a frank chat about budget.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Price it properly
Once the engineer's calculations are in, we fix the build price in writing, with a clear list of what's included.
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 Liverpool

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

Our guide for North West England, which covers Liverpool, is £1,900–£2,610 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 £68,500–£94,000. 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 Liverpool?

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 Liverpool?

We cover Liverpool (L1, L2, L3, L69 and L70) and nearby places including Kensington, Kirkdale and Birkenhead, plus the rest of Merseyside. The first site visit is free.

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 Liverpool

All two-storey extension services in Liverpool · Part single, part two-storey extensions across Merseyside

The quickest next step is a visit. We'll look at your house in Liverpool and give you an honest view of the options.