Two-storey side extensions in Brockley
A two-storey side extension is one of the most space-efficient ways to add bedrooms and living space to a house in Brockley, because the new floors share one set of foundations and one roof.
The basics for Brockley at a glance.
- Postcode districts
- SE4
- County / area
- Greater London, England
- Price region
- London
- Guide price
- £103,500–£138,500 (£2,460–£3,300 per m²)
- Approval route
- Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
- Nearest towns
- New Cross (0.8 miles), Crofton Park (0.8 miles), Ladywell (0.9 miles)
- First visit
- Free, no obligation
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.
Around Brockley we also work in New Cross, Crofton Park and Ladywell, and across the rest of Greater London. Postcode district in and near Brockley: SE4.
What it costs in Brockley
For budgeting in Brockley, allow around £103,500–£138,500 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 £2,460–£3,300 per m² including VAT for London. 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 | £2,260–£3,040 per m² | £95,000–£127,500 |
| Standard | £2,460–£3,300 per m² | £103,500–£138,500 |
| Premium | £2,950–£3,960 per m² | £124,000–£166,500 |
Planning and building regulations in Brockley
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 Brockley homes
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.
Matching the ridge and roof
A hipped house usually needs a hipped extension roof, and a gabled house a gable. Matching the pitch, tiles, ridge detail and brick bond is what makes a side extension look original rather than added, and councils look closely at it on a front-facing addition.
How we'd run your project
Measure and listen
A visit to Brockley to understand how you live in the house now and what the extra rooms need to do, plus a first look at the structure.
Drawings, then consent
We draw the scheme, check it against the rules in England, and take it through the right consent with the council.
Fixed price in writing
With approved drawings and calculations, we give you a fixed build price and a programme you can plan around.
On site
One project lead runs the job, keeps you updated and arranges inspections at each stage until completion.
Questions about two-storey side extensions in Brockley
How long does a two-storey side extension 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.
Do I need planning permission for a two-storey side extension in Brockley?
Brockley 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.
Which postcodes do you cover around Brockley?
We cover Brockley (SE4) and nearby places including New Cross, Crofton Park and Ladywell, plus the rest of Greater London. The first site visit is free.
Who handles building regulations for a project in Brockley?
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.
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 free site visit before any drawings are prepared.
Nearby
The same service in neighbouring towns:
Other extensions in Brockley
- 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 Brockley · Two-storey side extensions across Greater London
Ready to talk it through? Call us or send the form and we'll arrange a visit to your home in Brockley.