Building regulations for extensions in County Down
We prepare building regulations for extensions for homes across County Down, on their own or as the first stage of a full design and build project.
- Guide priceFrom £750 inc VAT
- Approval routeFull plans or building notice to council
- Towns covered5
- Site visitFree, no obligation

Towns in County Down
Local to County Down
Towns we cover in County Down include Bangor, County Down, Newtownards, Newry, Banbridge, Downpatrick. In Northern Ireland, extension projects follow the NI planning rules and council building control, which we account for from the first survey.
Design and approval fees for County Down
These are guide fees for County Down, adjusted for Northern Ireland (×0.86) and including VAT. Council application and inspection fees are paid separately.
| Option | What it covers | Guide price |
|---|---|---|
| Essential | Building regulations drawings for a simple single-storey extension | £750 – £1,550 |
| Standard | Drawings plus structural calculations | £1,100 – £2,250 |
| Premium | Complex or two-storey pack with energy calculations | £1,850 – £3,300 |
Our design fee only. Building control charges are set by your council (or, in England and Wales, a registered building control approver) and quoted separately.Council fees are extra and are set by the Northern Ireland Executive.
Want a range for your exact size? The guide-price tool takes about a minute.
Do I need planning permission in County Down?
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.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
Northern Ireland has no Party Wall Act. Where work is on or close to a shared boundary, we agree access and protection with your neighbour in writing before work starts.
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 is included
- Structural calculations for beams, lintels and foundations
- Energy and glazing checks, including whole-house calculations if needed
- Building regulations drawings and written specification
- Inspection bookings throughout the build
- Completion certificate on sign-off
Building regulations approval and planning permission are separate. A design can have planning consent and still need changes to meet the regulations, which is why we draw for both together.
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
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
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 County Down
Do I need building regulations approval in County Down?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Will my neighbours in County Down 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.
How long does this take for a County Down home?
2–5 weeks for drawings, depending on the council and the complexity of the project.
Full plans or building notice?
A full plans application gets the drawings checked before work starts, which we usually recommend for extensions. A building notice is quicker to submit but carries more risk if something needs changing on site.
Book a free site visit in County Down
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.