Extra bedroom and en-suite extensions in Derby
Adding an extra bedroom and en-suite extension in Derby gives you two new rooms stacked on one footprint. Here's how we'd approach it, what it typically costs and the rules that apply in England.
Useful details for planning an extra bedroom and en-suite extension in Derby.
- Postcode districts
- DE1, DE3 and DE22
- County / area
- Derbyshire, England
- Price region
- East Midlands
- Guide price
- £55,000–£74,000 (£1,960–£2,650 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
- Chaddesden (1.8 miles), Oakwood (Derbyshire) (2.4 miles), Sinfin (2.9 miles)
- First visit
- Free, no obligation
About an extra bedroom and en-suite extension
An extra bedroom and en-suite extension is a two-storey extension planned around a new double bedroom with its own shower room on the first floor, with a ground-floor room below. It is one of the most effective ways to add space for a growing family. Nationwide's 2025 research linked adding a double bedroom and bathroom to a three-bed, one-bathroom house with value gains of up to 24%.
We cover Derby (DE1, DE3 and DE22) and the places around it, including Chaddesden (1.8 miles), Oakwood (Derbyshire) (2.4 miles) and Sinfin.
What it costs in Derby
Expect an extra bedroom and en-suite extension in Derby to land somewhere around £55,000–£74,000 (plus £5,500–£11,000 for the en-suite) for a 4 m × 3.5 m footprint on two floors (28 m² of new floor space). Our East Midlands guide rate is £1,960–£2,650 per m², including VAT. 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 | £1,800–£2,430 per m² | £50,500–£68,000 |
| Standard | £1,960–£2,650 per m² | £55,000–£74,000 |
| Premium | £2,350–£3,180 per m² | £66,000–£89,000 |
Planning and building regulations in Derby
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 Derby homes
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.
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.
How we'd run your project
Measure and listen
A visit to Derby 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 and permission
Our designers produce plans and elevations, then we take care of planning or permitted development checks with the council covering Derby.
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 extra bedroom and en-suite extensions in Derby
Do I need planning permission for an extra bedroom and en-suite extension in Derby?
Derby 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.
Which postcodes do you cover around Derby?
We cover Derby (DE1, DE3 and DE22) and nearby places including Chaddesden, Oakwood (Derbyshire) and Sinfin, plus the rest of Derbyshire. The first site visit is free.
Who handles building regulations for a project in Derby?
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.
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.
Can an en-suite go in a room with no window?
Yes. A shower room without a window is allowed, provided it has a mechanical extract fan to the outside that meets Part F. Many people prefer a window for daylight, but if it faces a neighbour it will usually need obscure glass. We plan the extract route early so the duct is hidden.
Nearby
Close to Derby? We work across the area, including:
Other extensions in Derby
All two-storey extension services in Derby · Extra bedroom and en-suite extensions across Derbyshire
Ready to talk it through? Call us or send the form and we'll arrange a visit to your home in Derby.