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 Cookstown?
In Cookstown, a side extension typically costs £1,450–£2,300 per m² of floor area, including VAT at 20% (standard rate). For a typical 28 m² project that is roughly £40,500–£64,500. That range is adjusted for Northern Ireland, where domestic building work typically costs around 14% below the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (20 m²) | £29,000–£46,000 |
| Typical project (28 m²) | £40,500–£64,500 |
| Larger project (39 m²) | £56,500–£89,500 |
| Rate per m² | £1,450–£2,300 |
The main things that change the cost:
- Internal fit-out of the new rooms
- Steel work where the side wall is opened
- Single or two storeys
- Drains, gas meters or soil pipes that need moving
Use the guide price tool to see how size and specification change the figure, then ask for a written, itemised quote.
Do you need planning permission for a side extension in Cookstown?
Here is how the rules work for a side extension in Northern Ireland. In Northern Ireland a single-storey side extension can be permitted development if it is no more than 4 metres high, no wider than half the original house and not beside a wall facing a road. Side extensions of more than one storey need planning permission.
In Northern Ireland building control approval comes from the council, usually through a full plans application or a building notice, with inspections during the work and a completion certificate at the end.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
Handled as part of most side extensions:
- Opening into the existing house
- Planning drawings and application
- Foundations and drainage alterations
- Survey of the boundary, drains and access
- Walls, roof and windows to match the house
- Structural calculations
How long does it take?
Build time is typically 10 to 16 weeks on site depending on size and storeys. Design and approvals come first and typically take 3 to 4 months, depending on the approval route.
Building in Cookstown
Across Northern Ireland, bungalows and chalet bungalows are common, so loft conversions and rear extensions are popular projects.
Our Cookstown coverage includes postcode districts BT80, and we also work in nearby places such as Magherafelt, Dungannon and Portadown.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 04
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about side extensions in Cookstown
Will a two-storey side extension look odd?
Not if it is designed well. Setting it back from the front and keeping the roof lower than the main ridge usually gives a natural look and is what most councils ask for.
Do I need planning permission for a side extension in Cookstown?
In Northern Ireland a single-storey side extension can be permitted development if it is no more than 4 metres high, no wider than half the original house and not beside a wall facing a road. Side extensions of more than one storey need planning permission.
How long does a side extension take in Cookstown?
Typically 10 to 16 weeks on site depending on size and storeys. Design and approvals beforehand usually take 3 to 4 months.
How much does a side extension cost in Cookstown?
In Cookstown, a side extension typically costs £1,450–£2,300 per m² of floor area, including VAT at 20% (standard rate). A typical 28 m² project comes to roughly £40,500–£64,500. Your fixed price depends on the survey and drawings.
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.
Can a side extension go over a drain?
Often yes, with a build-over agreement from the water company or by rerouting the drain. We check this during the survey.