What is a side extension?
A side extension builds into the space beside a semi-detached or detached house, often over a driveway or side passage. It can be single-storey, for a utility room, downstairs toilet or study, or two-storey to add a bedroom above.
How much does a side extension cost in Stockton-on-Tees?
In Stockton-on-Tees, a side extension typically costs £1,550–£2,400 per m² of floor area, including VAT at 20% (standard rate). For a typical 28 m² project that is roughly £43,500–£67,000. Building costs in the North East run about 10% below the UK average, and the figures for Stockton-on-Tees are adjusted to reflect that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (20 m²) | £31,000–£48,000 |
| Typical project (28 m²) | £43,500–£67,000 |
| Larger project (39 m²) | £60,500–£93,500 |
| Rate per m² | £1,550–£2,400 |
The biggest cost drivers are:
- Boundary walls and access for materials
- Drains, gas meters or soil pipes that need moving
- Steel work where the side wall is opened
- Roof design and tile matching
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a side extension in Stockton-on-Tees?
Before anything is built in Stockton-on-Tees, we confirm which approvals apply in England. In England a single-storey side extension can be permitted development if it is no more than 4 metres high and no wider than half the width of the original house. Side extensions of more than one storey always need planning permission, as do side extensions in conservation areas, National Parks and National Landscapes.
Where work involves a shared wall, building on the boundary, or digging foundations within 3 metres of a neighbour’s building and deeper than its foundations (or within 6 metres for deeper work), the Party Wall etc. Act 1996 applies and notices must be served before work starts.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
The work we manage on a side extension:
- Foundations and drainage alterations
- Survey of the boundary, drains and access
- Walls, roof and windows to match the house
- Opening into the existing house
- Structural calculations
- Electrics, heating and plastering
How long does it take?
Build time is typically 10 to 16 weeks on site depending on size and storeys. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Stockton-on-Tees
Across the North East, colliery-era terraces and newer estates sit side by side, so the right project depends on the house type.
Projects in Stockton-on-Tees (TS19) are surveyed in person before we quote, so the price reflects your actual property.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about side extensions in Stockton-on-Tees
How much does a side extension cost in Stockton-on-Tees?
In Stockton-on-Tees, a side extension typically costs £1,550–£2,400 per m² of floor area, including VAT at 20% (standard rate). A typical 28 m² project comes to roughly £43,500–£67,000. Your fixed price depends on the survey and drawings.
Can I build a side extension without planning permission?
In England a single-storey side extension can be permitted development if it is no more than 4 metres high and no wider than half the original house, and the house is not in a conservation area or similar protected land. Two-storey side extensions always need planning permission.
Will I lose my driveway?
A side extension often takes the side drive. We look at whether parking can be kept at the front and whether a dropped kerb is needed.
Do you build side extensions in Stockton-on-Tees?
Yes. We build side extensions across Stockton-on-Tees, including postcodes TS19. Every project starts with a free home visit.
How close to the boundary can I build?
You can build up to the boundary, but the eaves height near it is limited under permitted development, and planning officers often want a gap at first floor. If you build on or near a shared boundary, party wall rules may apply.