Castlereagh home office extensions, designed and built
Planning a home office extension in Castlereagh? We survey the house, work out the planning route, draw the design and build it, so you deal with one team from the first visit to the completion certificate.
- Guide price in CastlereaghFrom £13,500 inc VAT
- PlanningNI permitted development (rear 3–4 m) or planning
- Build time8–12 weeks on site
- Postcode districtsBT1, BT2, BT4, BT5, BT6
Planning rules that apply in Castlereagh
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.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
Building close to a public sewer needs the agreement of NI Water, which we check during design.
Applications are decided by your council, which handles local planning in Northern Ireland.
What should I budget for a home office extension 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: £1,590 to £2,920 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2.5 m × 3.2 m 8 m² | £13,500 – £16,500 | £14,500 – £19,000 | £18,500 – £23,500 |
| 3 m × 3.6 m 11 m² | £17,500 – £21,000 | £20,000 – £26,000 | £25,500 – £32,500 |
| 3 m × 5 m 15 m² | £23,500 – £28,500 | £27,500 – £35,000 | £34,500 – £44,000 |
Try the guide-price tool to see a range for your own size and finish.
Is a home office extension right for your house?
- Households that need a second quiet room
- Homes where a loft or garden room is not practical
- People who work from home most of the week
North-facing glass and rooflights give steadier light for screen work. Where the office faces south, we use deeper reveals or external shading to keep glare and heat down.
Local to Castlereagh
Our survey diary covers Castlereagh, including BT1, BT2, BT4, BT5, BT6, BT7. We also work in nearby Belfast (2 miles), Newtownabbey (6 miles), Lisburn (7 miles), Carrickfergus (10 miles).
For homes towards County Down, Newtownards is around 8 miles away. Northern Ireland's housing ranges from city terraces to large numbers of detached houses and bungalows on rural plots, many in render, where single-storey extensions fit easily.
From first visit to completion
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
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
The build is managed from start to finish, inspected at each stage and signed off on completion.
Home office extension questions answered
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.
How long does a home office extension take to build in Castlereagh?
On site, typically 8 to 12 weeks once approvals are in place. Before that, allow 4–10 weeks design and approvals.
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 claim the cost against tax?
Building work on your home is not normally an allowable business expense, and claiming it can have capital gains tax effects. Speak to an accountant before assuming any tax relief.
Is an attached office better than a garden office?
An attached office shares the house heating and broadband, adds floor area to the home, and needs no garden path in the rain. A garden building can be cheaper and quicker but is a separate structure.
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.