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 Belfast?
In Belfast, 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. 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 (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 |
The main things that change the cost:
- Steel beams and propping of the back addition
- Glazed roof specification
- Moving drains and soil stacks
- Length of the side return
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 Belfast?
Approvals for a side return extension in Belfast follow the rules for 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.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
The work we manage on a side return extension:
- Written agreement with neighbours on shared walls
- Glazed or solid roof with insulation
- Written agreement with neighbours on shared walls
- Building control sign-off
- Foundations and drainage, including any build-over agreement
- Floor levelling, heating and electrics
How long does it take?
Allow 10 to 14 weeks on site. Before that, surveys, drawings and approvals usually take 3 to 4 months, longer if the council asks for changes.
Building in Belfast
Northern Ireland has many detached and semi-detached homes on generous plots, which suits single-storey rear extensions and garage conversions.
Our Belfast coverage includes postcode districts BT1, BT2, BT3 and BT4, and we also work in nearby places such as Newtownabbey, Lisburn and Newtownards.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about side return extensions in Belfast
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.
Do I need planning permission for a side return extension in Belfast?
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.
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.
Do you build side return extensions in Belfast?
Yes. We build side return extensions across Belfast, including postcodes BT1, BT2, BT3 and BT4. Every project starts with a free home visit.
How much does a side return extension cost in Belfast?
In Belfast, 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.
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.