Extra bedroom and en-suite extensions in Hornsey
If you live in Hornsey and need more room without moving, an extra bedroom and en-suite extension is worth a serious look. We handle the drawings, approvals, structure and build.
Hornsey: the key facts for this kind of project.
- Postcode districts
- N8
- County / area
- Greater London, England
- Price region
- London
- Guide price
- £67,000–£90,500 (£2,400–£3,240 per m²), plus £5,500–£11,000 for the en-suite
- 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
- Crouch End (0.5 miles), Muswell Hill (0.9 miles), Wood Green (0.9 miles)
- First visit
- Free, no obligation
About an extra bedroom and en-suite extension
This service suits you if you need another bedroom, or want a main bedroom with its own bathroom, without converting the loft or moving. You get a first-floor layout that connects well to your landing, an en-suite designed for plumbing and ventilation, a useful room downstairs, the approvals your nation needs and the build, managed by us and carried out by vetted teams working under S&K.
We cover Hornsey (N8) and the places around it, including Crouch End (0.5 miles), Muswell Hill (0.9 miles) and Wood Green.
What it costs in Hornsey
For budgeting in Hornsey, allow around £67,000–£90,500 (plus £5,500–£11,000 for the en-suite) for an extra bedroom and en-suite extension with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space). That's based on £2,400–£3,240 per m² including VAT for London. The fastest way to a firmer number is a free site visit, after which we price the design stage in writing.
| 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 Hornsey
In England, an extra bedroom extension at the rear 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. Upper side windows, including en-suite windows, must be obscure-glazed and non-opening below 1.7 m. Side or deeper designs 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 Hornsey homes
Connecting to the landing
The new bedroom must be reached from the existing landing, usually through a new opening in the outside wall or by taking part of an existing bedroom as a corridor. We look at the stairs and landing first, because a poor connection can waste much of the new space.
Sound and privacy
Bedrooms above a kitchen or family room benefit from an insulated floor to reduce noise. Side-facing upstairs windows usually have to be obscure-glazed, so we place the main bedroom window to the rear and the en-suite window to the side where possible.
How we'd run your project
Start at your house
We come to your home in Hornsey, measure up, check the ground floor walls and roof structure, and note anything near the boundaries.
Drawings and permission
Our designers produce plans and elevations, then we take care of planning or permitted development checks with the council covering Hornsey.
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 it
The new structure goes up first, then we open into the house, finish inside and get the completion certificate.
Questions about extra bedroom and en-suite extensions in Hornsey
How much does an extra bedroom and en-suite extension cost in Hornsey?
Our guide for London, which covers Hornsey, is £2,400–£3,240 per m² including VAT. A typical project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space) comes to about £67,000–£90,500 (plus £5,500–£11,000 for the en-suite). 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 Hornsey?
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 Hornsey?
We cover Hornsey (N8) and nearby places including Crouch End, Muswell Hill and Wood Green, plus the rest of Greater London. The first site visit is free.
What goes on the ground floor below a new bedroom?
Whatever suits you: a bigger kitchen, a family room, a study, a utility or a downstairs shower room. The ground floor usually costs about the same whatever it is used for, apart from kitchen units and bathroom fittings, which are priced separately.
Does an extra bedroom add value to my house?
It usually does, though not always by the full cost. Nationwide's 2025 research found that adding a double bedroom to a two-bed house was linked to about 13% higher value, and a double bedroom and bathroom on a three-bed, one-bathroom house up to 24%. Local ceiling prices still apply.
Nearby
The same service in neighbouring towns:
Other extensions in Hornsey
All two-storey extension services in Hornsey · Extra bedroom and en-suite extensions across Greater London
Tell us about your house in Hornsey and we'll call you back to arrange a free, no-obligation visit.