What is a side return extension?
A side return extension fills the narrow passage that runs alongside the back addition of many Victorian and Edwardian terraced houses. It widens a galley kitchen into a proper kitchen-diner, usually with a sloping glazed roof to keep the room bright.
How much does a side return extension cost in County Antrim?
In County Antrim, a side return extension typically costs £2,000–£2,850 per m² of floor area, including VAT at 20% (standard rate). For a typical 12 m² project that is roughly £24,000–£34,000. We start from a UK-wide guide and adjust it for Northern Ireland, where labour and materials are typically about 14% below average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (8 m²) | £16,000–£23,000 |
| Typical project (12 m²) | £24,000–£34,000 |
| Larger project (17 m²) | £34,000–£48,500 |
| Rate per m² | £2,000–£2,850 |
What moves the price most:
- Steel beams and propping of the back addition
- Access through the house for materials
- Length of the side return
- Agreements with neighbours on shared walls
A guide range is only a starting point: the guide price tool gives an instant figure for your size, and a free survey turns it into a fixed quote.
Do you need planning permission for a side return extension in County Antrim?
Whether you need planning permission depends on your house and its location in Northern Ireland. In Northern Ireland a single-storey side infill can be permitted development if it is no more than 4 metres high and no wider than half the original house; conservation areas need planning permission. Building control approval is needed before work starts.
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.
We check this for your address before design work starts, so there are no surprises later.
What we handle
Handled as part of most side return extensions:
- Steel beams to remove the side wall
- Drawings and planning or permitted development check
- Glazed or solid roof with insulation
- Floor levelling, heating and electrics
- Written agreement with neighbours on shared walls
- Written agreement with neighbours on shared walls
How long does it take?
Allow 10 to 14 weeks on site. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in County Antrim
Northern Ireland has many detached and semi-detached homes on generous plots, which suits single-storey rear extensions and garage conversions.
Towns we cover in County Antrim include Belfast, Lisburn, Newtownabbey, Carrickfergus, Ballymena and Antrim.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about side return extensions in County Antrim
Is a glass roof too hot or cold?
Modern solar-control double or triple glazing reduces glare and heat loss. Building regulations also limit how much glazing you can have unless the design shows it performs well enough.
How much space does a side return add?
Typically 1.5 to 2.5 metres of width along the back addition. It often turns a narrow galley kitchen into a family kitchen-diner.
How do you get materials in?
Mid-terrace houses often have no rear access, so materials come through the house. We protect floors and plan deliveries carefully.
How much does a side return extension cost in County Antrim?
In County Antrim, a side return extension typically costs £2,000–£2,850 per m² of floor area, including VAT at 20% (standard rate). A typical 12 m² project comes to roughly £24,000–£34,000. Your fixed price depends on the survey and drawings.
Do I need planning permission for a side return extension in County Antrim?
In Northern Ireland a single-storey side infill can be permitted development if it is no more than 4 metres high and no wider than half the original house; conservation areas need planning permission. Building control approval is needed before work starts.
Do you build side return extensions in County Antrim?
Yes. We build side return extensions across County Antrim, including postcodes BT1, BT10, BT11, BT12 and BT13. Every project starts with a free home visit.