Extension plans and drawings across County Down
We prepare extension plans and drawings for homes across County Down, on their own or as the first stage of a full design and build project.
- Guide priceFrom £1,000 inc VAT
- PlanningWe find the right route for you
- Towns covered5
- Site visitFree, no obligation

Towns in County Down
Working in 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.
Planning and approvals in County Down
In Northern Ireland we check the permitted development limits for your house type and, where needed, apply to your council for planning permission, then submit full plans or a building notice to council building control.
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.
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.
When it helps
- Anyone who wants fixed designs before getting build prices
- Homeowners at the very start of a project
- Projects that need a planning application or other approval
The most expensive changes are the ones made after the steel is ordered. A good design stage settles layout, heights, glazing and services on paper, so the build price is firm.
Design and approval fees for County Down
Fees below are our County Down guide (×0.86, the Northern Ireland factor), including VAT. Council and building control fees are extra.
| Option | What it covers | Guide price |
|---|---|---|
| Essential | Measured survey and planning drawings | £1,000 – £1,900 |
| Standard | Planning drawings plus building regulations drawings | £1,850 – £3,300 |
| Premium | Full pack with structural calculations and 3D visuals | £2,900 – £4,750 |
Want a range for your exact size? The guide-price tool takes about a minute.
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
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
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 you cover all of County Down?
Yes, across the whole of County Down. Site visits are free and there is no obligation.
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.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for County Down, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Can I use your drawings with another builder?
Yes. Once paid for, the drawings are yours to use for your project.
Do I need an architect?
Not necessarily. For most extensions an experienced designer or architectural technologist is enough. For listed buildings or complex sites an architect’s input can help.
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.