Extra bedroom and en-suite extensions in Stockton-on-Tees

Before you start in Stockton-on-Tees, here's what applies.

Postcode districts: TS18, TS19 and TS21
County / area: County Durham, England
Price region: North East England
Guide price: £50,500–£68,000 (£1,800–£2,430 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: Billingham (1.8 miles), Thornaby-on-Tees (2.5 miles), Middlesbrough (3.4 miles)
Distance to Darlington: about 9.8 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%.

Stockton-on-Tees sits about 9.8 miles from Darlington. Closer to home, Billingham is 1.8 miles away and Thornaby-on-Tees 2.5 miles.

What it costs in Stockton-on-Tees

In North East England, which includes Stockton-on-Tees, we'd expect an extra bedroom and en-suite extension to cost around £50,500–£68,000 (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), or £1,800–£2,430 per m² including VAT. 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	£1,660–£2,240 per m²	£46,500–£62,500
Standard	£1,800–£2,430 per m²	£50,500–£68,000
Premium	£2,160–£2,920 per m²	£60,500–£81,500

Planning and building regulations in Stockton-on-Tees

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 Stockton-on-Tees 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.

Planning the en-suite

An en-suite needs a route for the soil pipe to the drains, enough fall for waste water and an extract fan to the outside under Part F. Placing it over the ground-floor utility or near an existing drain keeps pipework short and hidden.

How we'd run your project

Free site visit
We visit your home in Stockton-on-Tees, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Detail and price
Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.
Build and sign-off
Vetted teams working under S&K build the extension, and we arrange the building control completion certificate at the end.

Questions about extra bedroom and en-suite extensions in Stockton-on-Tees

How long does an extra bedroom and en-suite 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.

Which postcodes do you cover around Stockton-on-Tees?

We cover Stockton-on-Tees (TS18, TS19 and TS21) and nearby places including Billingham, Thornaby-on-Tees and Middlesbrough, plus the rest of County Durham. The first site visit is free.

How much does an extra bedroom and en-suite extension cost in Stockton-on-Tees?

Our guide for North East England, which covers Stockton-on-Tees, is £1,800–£2,430 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 £50,500–£68,000 (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.

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.

How big should a new double bedroom be?

There is no legal minimum size for a bedroom in a house you own, so the test is whether it works. A comfortable double needs room for the bed with space to walk round it, wardrobes and a door that opens freely. We draw furniture on the plans so you can judge the space before anything is built.

Nearby

We also cover places near Stockton-on-Tees, including:

Other extensions in Stockton-on-Tees

All two-storey extension services in Stockton-on-Tees · Extra bedroom and en-suite extensions across County Durham

Ready to talk it through? Call us or send the form and we'll arrange a visit to your home in Stockton-on-Tees.