A double-storey extension adds two floors of new space to your house in one build, typically a larger kitchen or living room downstairs with an extra bedroom, bathroom or en-suite above, sharing one set of foundations and one roof.
We take on a double-storey extension throughout Stockton-on-Tees and the surrounding TS17, TS18, TS19 and TS20 postcodes, as well as in Billingham, Thornaby-on-Tees and Middlesbrough. The guide range for this work in the North East is £54,000–£108,000 including VAT; where your project falls depends on its size, the materials you pick and how easy the site is to reach. A free survey turns that range into a fixed figure.
- Guide price
- £54,000–£108,000 inc VAT
- Time on site
- 14–22 weeks on site
- Postcodes
- TS17, TS18, TS19 and TS20
- Planning rules
- England
- Local area
- County Durham
- Survey
- Free, with a written quote
How much does a double-storey extension cost in Stockton-on-Tees?
Prices for a double-storey extension vary from house to house, but in Stockton-on-Tees most projects fall within £54,000–£108,000 including VAT. That reflects costs in the North East, about 10% below the national guide. Treat the table as a budgeting aid; the written figure follows a survey we carry out for free.
| Type of job | What it usually involves | Guide in Stockton-on-Tees |
|---|---|---|
| Small (15–20m² total) | A compact rear or side extension adding a small room on each floor. | £36,000–£58,000 |
| Typical (30–40m² total) | A larger kitchen or living room below with a double bedroom or en-suite above. | £54,000–£108,000 |
| Large (50m² plus total) | Wide or deep extensions, often with a new bathroom, steelwork and high-spec glazing. | £90,000–£162,000 |
Expect these to shape the final quote:
- Combined floor area across both storeys
- How the new roof joins the existing roof
- Foundation depth, ground conditions and drains to divert
- Scaffolding duration, access and the level of finishes
Scope of the work
- Groundworks, foundations and below-ground drainage
- Insulated cavity walls with brick or render to match the house
- Roof structure tied into the existing roof, tiled to match
- Scaffolding for the full build, erected and inspected
- Windows, external doors, plastering and internal doors
- Building control inspections and completion certificate
Homes in County Durham
Colliery villages across County Durham are lined with brick and stone terraces, many built for mining families. Durham City has Georgian and Victorian streets, Darlington has Victorian terraces and villas, and Peterlee and Newton Aycliffe were planned as post-war new towns. Dales farmhouses in Weardale and Teesdale are stone, often under stone or slate roofs.
Colliery terraces commonly suit loft rooms, rear extensions and window replacement, and many need repointing. New-town homes often benefit from rendering or cladding upgrades and roofline renewal, while stone farmhouses may need lime work.
So when we survey a Stockton-on-Tees property for a double-storey extension, the first step is working out how it was built and what has been changed since.
Permissions for a double-storey extension in Stockton-on-Tees
Planning law differs across the UK. For a home in Stockton-on-Tees, it is the England rules below that count, and we check them with the council ahead of any quote.
In England, a two-storey rear extension can only be permitted development if it is no more than 3 m deep, at least 7 m from the rear boundary and finished to match the house. Most double-storey and all two-storey side extensions need full planning permission.
Building Regulations approval is needed, with structural calculations for beams, foundations and the roof. The Party Wall etc. Act 1996 often applies on semi-detached and terraced houses.
Rules change and every property is different, so we check the planning history and constraints for your address before we quote.
From survey to handover
We look at the job
A free survey comes first. It gives us what we need to price a double-storey extension properly, including dimensions, existing materials and access for deliveries, and gives you the chance to ask anything you like.
Your fixed price
The quote arrives in writing, not over the phone. It covers the full scope, the finishes you've chosen, any exclusions and the payment schedule, with a fixed price tied to that specification.
Getting ready
With the quote agreed, we book the work in and handle preparation: permissions where needed, building control notifications, material orders and access arrangements for your Stockton-on-Tees property.
The work itself
During the work we protect the areas around it and tidy up at the end of each day. Once complete, we check the finish, remove our materials and hand over paperwork such as building control sign-off where it applies.
Working with SK Home Improvements
Questions about a double-storey extension in Stockton-on-Tees
Can you combine a double-storey extension with other work?
Yes. Because we manage several trades under one contract, we can plan a double-storey extension alongside other work on your Stockton-on-Tees home, such as new windows with rendering, or a kitchen refit with an extension. Combining jobs can reduce repeat set-up such as scaffolding, skips and access, and every element is listed and priced in the same written quote.
Do I need planning permission for a two-storey extension?
Most two-storey extensions need planning permission, but it depends on the size, height and position, your home's location, whether it is listed or in a conservation area, and which UK nation you are in. In England, a two-storey rear extension can sometimes be built under permitted development if it is no deeper than 3m and at least 7m from the rear boundary. We check what applies before quoting.
Can the new upstairs room have its own bathroom?
A new upstairs room can usually have an en-suite, provided waste pipes can reach the soil stack or a new one can be installed. Running the waste pipe to the right falls is the main design question, and a pumped system is an option where gravity will not work. We plan bathroom positions at the design stage so pipes, ventilation and insulation are built in rather than added later.
What happens at the survey?
We visit your home at a time that suits you, look at the area involved, take measurements and check access, condition and any services that might be affected. We talk through what you want from a double-storey extension, explain the options and answer questions. There is no charge and no obligation; afterwards we send a written quote.
Can we live at home while it is built?
Most families stay at home during a double-storey extension. The new structure is built outside first, and we only break through into the existing rooms near the end, usually one floor at a time. Upstairs, this may mean a bedroom is out of use for a week or two. We fit dust screens, protect floors and stairs, and plan any time without water or power in advance.
Nearby towns
Stockton-on-Tees and its TS17, TS18, TS19 and TS20 postcodes are part of our coverage. Homeowners in Billingham, Thornaby-on-Tees and Middlesbrough can also book a free survey with us and receive a written price for their job.