Builder

In Northern Ireland, many extensions are covered by Permitted Development rights — meaning you do not need planning permission. Generally, a single-storey rear extension up to 4m deep (detached) or 3m deep (semi-detached) is permitted. However, permitted development rules differ from England and Wales, so always check with your local council or your builder before starting work.

Planning permission controls whether a development is acceptable in terms of its size, appearance and impact on neighbours. Building regulations ensure the construction is structurally safe, energy-efficient and has proper drainage and fire safety. You can sometimes need one without the other. Your builder should guide you through both processes.

A few habits help homeowners feel confident: get more than one written quote, ask for references from similar completed jobs and follow them up, check membership of a trade body such as the Federation of Master Builders, confirm public liability insurance is current and ask to see the certificate, and put the scope of work, timeline and payment arrangement in writing before anything starts. NI Trades is an introduction service and isn't party to the contract or payment terms — for advice tailored to your specific project, talk to a solicitor, surveyor or building consultant before work begins.

A typical single-storey rear extension (30–40m²) takes approximately 12–20 weeks from breaking ground to finished decoration. This includes groundworks (2–3 weeks), brickwork/block (3–4 weeks), roof (1–2 weeks), first fix plumbing and electrical (1–2 weeks), plastering (1–2 weeks), and second fix and decoration (3–4 weeks). Wet NI weather can add time to external works.