Delphi, 21, Killiney Heath, Killiney, Co. Dublin.

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• Planning permission for an extension in Ireland — the 45 m² exemption and a 94% grant rateDublin councils granted 94% of extension applications decided in the year to September 2026. Since 27 July 2026 a rear extension of up to 45 m² can be exempt. The conditions, when you still apply, the fee and the timeline.
• An Bord Pleanála appeal, now An Coimisiún Pleanála — four weeks, €220, and a 25% reversal rateThe Commission reversed the council in 25% of the 1,195 Dublin-area appeals decided in the two years to September 2026. Who can appeal, the four weeks, the €220 fee, why 240 appeals a year fail on procedure, and the odds by direction.
• Certificate of compliance with planning permission — what the architect's opinion covers and what it does notRetention applications were 17% of everything lodged in the GDA over 12 months, and a fifth of those decided were refused. What a certificate or opinion on compliance with planning permission says, who signs it, the Law Society and RIAI forms, and the gaps a buyer should close from the register.
• How long does planning permission last? Five years, and a 79% rate on extensions of durationA permission lasts five years from the grant. Dublin councils granted 79% of the 343 extension-of-duration applications lodged in the two years to September 2026. What "commenced" means and how to apply in time.