Homeowner guide
Built without planning permission? Retention, enforcement and the 7-year rule
Updated 2026-07-18 · checked against the sources below
Discovering that an extension, conversion or garden building never had the permission it needed is stressful - but the law here is mechanical, and knowing the machinery beats guessing. There are three moving parts: retention permission (legalising it), enforcement (the council's stick), and the 7-year rule (a time limit that protects less than people think). One warning up front: applying for retention does not pause enforcement, so sequence matters.
Retention permission: legalising what is built
Retention (section 34(12C) of the Planning Act) is a normal planning application for development that already exists - same newspaper and site notices (which must state it is for retention), same 8-week clock, same public submission window. The council judges it as if the works were proposed fresh: being built is no advantage.
The fees are the sting: retention costs roughly triple. A house is EUR 195 (or EUR 2.50 per m², whichever is greater) against the normal EUR 65; an extension or garage conversion is EUR 102 or EUR 2.50 per m² against EUR 34. If the decision is appealed, a first-party retention appeal at An Coimisiún Pleanála is EUR 660, against EUR 220 for a normal appeal.
Enforcement: how it actually unfolds
Anyone can complain to the planning authority in writing, and unless the complaint is trivial or vexatious the authority must issue a warning letter within 6 weeks. After investigating it can serve an enforcement notice requiring the works to stop, be removed or be modified - and non-compliance is where it gets serious: on summary conviction, fines up to EUR 5,000 and/or 6 months in prison, with daily fines for continuing breaches; on indictment the ceiling is millions. Two details worth knowing: the burden of proving works were exempt sits on you, not the council; and applying for retention - or even obtaining it after proceedings begin - is no defence to a prosecution already underway.
The 7-year rule - and its trap
Enforcement action cannot begin more than 7 years after unauthorised development commenced (for breaches of a permission's conditions, 7 years from the end of the permission's life). Conditions about the use of land are the exception: those can be enforced at any time.
The trap is in the vocabulary: after 7 years the development becomes immune from enforcement, but it never becomes authorised. Solicitors call it 'unauthorised but immune', and it surfaces exactly when you least want it - at sale or remortgage, when the buyer's solicitor asks for evidence of planning compliance. The cures are retention permission, or a Section 5 declaration confirming the works were exempt all along. Immunity keeps the council away; it does not fix your title.
Does the new 45 m² limit fix my old over-sized extension?
No. Exemption is judged against the law in force when the works were carried out. A 43 m² extension built in 2024 exceeded the then-40 m² limit and is unauthorised; the 45 m² limit commencing 27 July 2026 does not reach back to legitimise it - nothing in the new regulations or their announcements provides retrospective effect. The routes remain retention permission or, in time, unauthorised-but-immune status with its selling-day consequences.
A sensible sequence
First establish the facts: was permission actually needed? A surprising share of worried homeowners turn out to be covered by an exemption, and a Section 5 declaration (EUR 80, 4 weeks) proves it formally - the cheapest possible fix. If permission was needed, talk to a planning consultant before applying: retention refused is the worst position, because the works are then both unauthorised and formally rejected. And if a warning letter has already arrived, get advice immediately - the retention application will not stop the clock.
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Quick answers
I built an extension without permission - what should I do first?
Establish whether permission was actually needed: many works fall within the exemptions, and a Section 5 declaration (EUR 80) proves it. If permission was needed, retention is the legalisation route - but take advice first, because a refused retention application leaves you worse off, and retention does not halt any enforcement already moving.
Can the council still act after 7 years?
Generally no - enforcement must begin within 7 years of the development commencing. But conditions about the use of land can be enforced at any time, and immunity is not authorisation: the works remain unauthorised on your title, which matters at sale or remortgage.
How much does retention cost?
Roughly triple the normal fee: EUR 195 minimum for a house, EUR 102 minimum for an extension (or EUR 2.50 per m² if greater), plus EUR 660 for a first-party appeal at An Coimisiún Pleanála. The real costs are professional fees and the risk of conditions or refusal.
Will the July 2026 rule changes legalise my existing build?
No. Exemption is assessed against the rules in force when you built. Works that exceeded the old limits stay unauthorised regardless of the new, larger limits - the fix is retention or, eventually, immunity with its caveats.
Sources
Related
General guidance, not legal or planning advice. The regulations and your local authority's interpretation bind; conditions and local rules (protected structures, architectural conservation areas, flood zones) can change the answer for a specific property. When in doubt, ask your council for a Section 5 declaration or talk to a planning consultant.