County Down · Northern Ireland

Building regulations for two-storey extensions in County Down

We handle building regulations approval for homeowners across County Down, from the first visit to the final paperwork.

County Down at a glance

Nation
Northern Ireland
Price region
Northern Ireland
Postcode areas
BT
Towns covered
15 listed below, plus surrounding villages
Site visits
Free, no obligation

What a building regulations application involves

Building regulations approval for a two-storey extension involves preparing technical drawings and a specification that show how the extension meets the rules on structure, fire safety, insulation, ventilation, electrics and drainage, getting them approved and having the work inspected. At the end you receive a completion certificate.

Towns in County Down include Bangor (County Down) (BT19), Newtownards (BT22), Newry (BT35), Banbridge (BT32), Dundonald (BT16) and Holywood (BT18). If yours isn't listed, we still cover it.

Fees

Technical drawings and specification are a guide of £1,500–£4,000. The council's building control fee depends on the value of the work; we confirm every fee in writing before the design stage starts.

Rules in Northern Ireland

In Northern Ireland, building control approval comes from the local council under the Building Regulations (Northern Ireland), with the Technical Booklets setting out how to comply. A full plans application is usual for two-storey extensions, and the council inspects the work and issues a completion certificate.

Approval in Northern Ireland: Planning application for works to a house: £347. Councils aim to decide local applications within an average of 15 weeks; many take longer.

Building control: Building control approval from the local council under the Building Regulations (Northern Ireland), using the Technical Booklets.

There is no Party Wall Act in Northern Ireland. Shared walls and boundaries are a matter of title and common law, so we agree access and record conditions with neighbours before work starts.

Getting the design right

Full plans and inspections

Full plans approval checks the design before work starts, which we recommend for two-storey extensions. Building control then inspects key stages, such as foundations, damp-proofing, drainage and insulation, before issuing the completion certificate.

How we work in County Down

  1. Understand the brief

    At your home in County Down we agree what you need: bedroom count, bathroom, kitchen space, and how much garden you want to keep.

  2. Get it approved

    Once you're happy with the design we submit it to the council for County Down and deal with any questions from the planning officer.

  3. Detail and price

    Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.

  4. Build it

    The new structure goes up first, then we open into the house, finish inside and get the completion certificate.

Towns we cover in County Down

Building regulations for two-storey extensions in County Down: questions

Do I need building regulations if I have planning permission?

Yes. Planning permission and building regulations are separate. Planning covers what the extension looks like and how it affects neighbours; building regulations cover how it is built and whether it is safe, warm and healthy. A two-storey extension needs both, unless permitted development replaces the planning part.

What is a build-over agreement?

A build-over agreement is permission from your water company to build over or near a public sewer. Many rear extensions sit near shared drains, and the water company will want access protected and the pipe checked. We check sewer records early so the agreement does not delay the start.

Neighbouring areas

All extension services in County Down · About building regulations for two-storey extensions

Ready to see what a second storey could do for your home?

Book a free site visit. We'll look at your house, talk through options and explain the approvals you'd need, then price the design stage in writing.

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