How long does planning permission last in Northern Ireland?
Five years. Once granted, planning permission in Northern Ireland is valid for five years under the Planning Act (Northern Ireland) 2011, so you must begin the development within that window or the permission lapses and you would need to reapply. Applying early costs you nothing in flexibility.
The rule is refreshingly simple: planning permission granted in Northern Ireland is valid for five years from the date of the decision, under the Planning Act (Northern Ireland) 2011. You must make a start on the development within those five years. If you do not, the permission lapses, and getting it back means a fresh application at the current fee (a householder application costs £347 under the fees in force from April 2025) with no guarantee the answer will be the same second time around, since policies and circumstances change.
What counts as "starting" matters. The commencement of development is a legal concept, and genuinely beginning the works, for example digging and pouring foundations in accordance with the approved plans, is the classic material start. A token gesture years in may be challenged, so if you are approaching the deadline and serious about the project, take advice and make a proper, documented start.
The five-year clock is also why applying early is smart rather than wasteful. If you are even reasonably sure you will extend within the next few years, securing permission now locks today’s decision in for five years while you save, get quotes and plan. Given that actual processing has been running at roughly 19 to 20 weeks against the 15-week statutory target, having permission in your pocket before you need it removes the slowest step from your build timeline entirely.
One related trap: planning permission and Building Regulations approval are separate regimes with separate lifespans and separate applications. Having live planning permission does not mean your Building Control approval is in place, and vice versa. Our planning guide walks through which of the two your project needs and in what order.
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Conor writes the NI building and renovation cost benchmark guides for NI Trades. He draws on a civil-engineering background and on quotes from working FMB, OFTEC and NICEIC tradespeople across Northern Ireland to keep the price ranges realistic. He holds a BEng (Hons) in Civil Engineering from Queen’s University Belfast.