Castlereagh side return extensions, designed and built
We design and build side return extensions for houses in Castlereagh, with a written price once the survey and design are done and one point of contact throughout.
- Guide price in CastlereaghFrom £15,000 inc VAT
- PlanningDepends on the NI limits; checked at the survey
- Build time10–14 weeks on site
- Postcode districtsBT1, BT2, BT4, BT5, BT6
Working in Castlereagh
Site visits are available across Castlereagh (BT1, BT2, BT4, BT5, BT6, BT7). Nearby, we also take on projects in Belfast (2 miles), Newtownabbey (6 miles), Lisburn (7 miles), Carrickfergus (10 miles).
Newtownards, in County Down, is roughly 8 miles from Castlereagh and also on our list. In Northern Ireland, extension projects follow the NI planning rules and council building control, which we account for from the first survey.
Side return extension prices in Castlereagh
Prices below are for Castlereagh, using the Northern Ireland factor of ×0.86. They are guide ranges including VAT for the build only, not a quote.
Typical rates in Castlereagh: £1,810 to £3,270 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 1.8 m × 4.5 m 8 m² | £15,000 – £18,500 | £16,500 – £21,000 | £20,500 – £26,500 |
| 2 m × 5.5 m 11 m² | £19,500 – £24,000 | £22,500 – £28,500 | £28,000 – £36,000 |
| 2.2 m × 7 m 15 m² | £27,000 – £32,500 | £30,500 – £39,000 | £38,500 – £49,500 |
For a figure based on your own dimensions, use our guide-price tool.
Will the council need to approve it?
In Northern Ireland the Planning (General Permitted Development) Order 2015 lets some single-storey rear extensions go ahead without planning permission, up to 3 m on a semi-detached or terraced house and 4 m on a detached house, within height and boundary limits. Larger, side and two-storey extensions normally need planning permission from the council, and building control approval is separate.
Homes in conservation areas, areas of townscape character and listed buildings have tighter rules, so we always check the property's status and planning history before design starts.
In Northern Ireland building control is run by the councils under the Building Regulations (Northern Ireland). We submit full plans or a building notice and book the inspections through to completion.
Applications are decided by your council, which handles local planning in Northern Ireland.
Is a side return extension right for your house?
- Homes where the garden is too small to lose much depth
- Victorian and Edwardian terraces with a rear outrigger
- Narrow galley kitchens
Light is the design problem. A side return can make the middle of the house darker if the roof is solid, so we model the daylight and usually recommend a glazed slope or a run of rooflights along the boundary edge.
How the project works
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Common questions in Castlereagh
Will my neighbours in Castlereagh be involved?
If a planning application is needed, the council notifies neighbours. Where work is close to a shared boundary, we agree access and protection with them in writing.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Castlereagh, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Who do I contract with for a side return extension in Castlereagh?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
Will the kitchen be darker?
Not if the roof is designed well. A glazed roof or a line of rooflights along the boundary usually makes the room brighter than before.
How much does a side return extension cost?
Our guide range is about £1,810 to £3,270 per m² including VAT, so a typical 2 m × 5.5 m infill lands around £22,500 to £28,500 at standard spec in Castlereagh, more in London.
Book a free site visit in Castlereagh
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.