Two-storey extensions for semi-detached houses in Ladywell

The basics for Ladywell at a glance.

Postcode districts: SE13
County / area: Greater London, England
Price region: London
Guide price: £67,000–£90,500 (£2,400–£3,240 per m²)
Approval route: Depends on position: a two-storey rear extension may be permitted development (3 m deep, 7 m from the rear boundary); a two-storey side extension needs planning permission.
Nearest towns: Crofton Park (0.6 miles), Lewisham (0.6 miles), Catford (0.7 miles)
First visit: Free, no obligation

About a two-storey extension for a semi-detached house

A two-storey extension for a semi-detached house is a two-floor addition to the rear, the open side, or both, designed around the attached neighbour on one side. The rear is often the simplest option and can sometimes be permitted development, while a side extension uses the gap on the detached side. Both need care with the shared party wall and the neighbour's light.

Around Ladywell we also work in Crofton Park, Lewisham and Catford, and across the rest of Greater London. Postcode district in and near Ladywell: SE13.

What it costs in Ladywell

Most of the cost of a two-storey extension for a semi-detached house is set by its size and specification. For Ladywell and the rest of London, our guide is £2,400–£3,240 per m² including VAT, so about £67,000–£90,500 for a 4 m × 3.5 m footprint on two floors (28 m² of new floor space). Design fees, structural calculations and approval fees are separate and listed on our prices page.

Spec	Per m²	A 4 m × 3.5 m footprint on two floors (28 m² of new floor space)
Essential	£2,210–£2,980 per m²	£62,000–£83,500
Standard	£2,400–£3,240 per m²	£67,000–£90,500
Premium	£2,880–£3,890 per m²	£80,500–£109,000

Planning and building regulations in Ladywell

In England, a two-storey rear extension on a semi can be permitted development if it goes no more than 3 m beyond the original rear wall and stays 7 m from the rear boundary, with matching materials and roof pitch. A two-storey side or wraparound extension always needs planning permission, costing £548 (or £575 for applications made from 8 December 2026). Protected areas such as conservation areas exclude two-storey rear permitted development.

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 Ladywell homes

The attached neighbour's light

A two-storey rear extension next to the party wall can take light from the neighbour's rear windows. Councils often use a 45-degree test, so the first floor may need to be shorter than the ground floor or set in from the shared boundary.

Rear, side or both

On a semi, a rear extension sits against the attached neighbour, while a side extension faces the detached neighbour and the street. We compare the space, cost and approval route for each, and for a wraparound, before you commit to one design.

How we'd run your project

Free site visit
We visit your home in Ladywell, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Get it approved
Once you're happy with the design we submit it to the council for Ladywell and deal with any questions from the planning officer.
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 two-storey extensions for semi-detached houses in Ladywell

Which postcodes do you cover around Ladywell?

We cover Ladywell (SE13) and nearby places including Crofton Park, Lewisham and Catford, plus the rest of Greater London. The first site visit is free.

Who handles building regulations for a project in Ladywell?

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 long does a two-storey extension for a semi-detached house 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.

What if my neighbour has already extended?

That often helps. An existing extension next door can reduce the effect of yours on their light, and may show what the council accepts on your street. It can also mean building alongside their wall, so we check its position, foundations and any windows facing your plot at the survey.

Will a side extension make my semi look like a terrace?

It can if it fills the whole gap to the boundary at first floor and the neighbour does the same. Many councils ask for a first-floor gap to the side boundary or a set-back for this reason. We design the extension to keep the semi reading as one of a pair.

Nearby

The same service in neighbouring towns:

Other extensions in Ladywell

All two-storey extension services in Ladywell · Two-storey extensions for semi-detached houses across Greater London

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