Updated for 2026
The updated 2026 rules give homeowners more flexibility for some extensions, outbuildings and dormers, but every exemption still depends on detailed conditions.
Planning a house extension, attic conversion, dormer window, garden room or wider home renovation in Ireland? Checking the planning requirements before appointing a contractor can help you avoid delays, additional costs and possible enforcement problems.
Ireland’s exempted-development rules changed on 27 July 2026, giving homeowners greater flexibility for certain residential projects. Every exemption remains subject to detailed conditions, so the measurements, position, previous development history and property status must be checked before construction begins.
Updated planning exemptions for 2026
For a detailed breakdown of the changes effective from 27 July 2026, read our new planning exemptions guide.
Key thresholds
What may qualify as exempted development
- Rear house extensions up to a total relevant area of 45 m²
- Side or rear sheds, stores, offices or gyms up to a combined 30 m²
- Certain side or rear dormer roof extensions up to 30 cubic metres
- Projects that satisfy all height, boundary, window and open-space conditions
House extension planning permission in Ireland
A rear house extension may now be exempt from planning permission where the total relevant extension area does not exceed 45 m². This calculation includes relevant previous extensions, including extensions that previously received permission. Conditions can also apply to height, windows, separation from boundaries and the amount of private open space remaining behind the property.
Garden room planning permission in Ireland
Sheds, stores, home offices, gyms and similar buildings at the side or rear of a house may qualify as exempted development up to a combined area of 30 m², subject to the applicable conditions. A standard outbuilding exemption does not automatically permit use as separate living accommodation, and a material change of use can require permission.
For a detached granny flat, family annexe or rear-garden home, see our dedicated guide to the new Class 3A rear-garden dwelling exemption. It has separate conditions from the garden-room exemption.
Attic conversion and dormer planning permission
An internal attic conversion may not require planning permission where it does not materially alter the external appearance or use of the property, but Building Regulations and fire-safety requirements can still apply. Certain side or rear dormer roof extensions and dormer windows may be exempt up to 30 cubic metres, provided the position, height, roof-edge and other conditions are satisfied. A front dormer is not included in this exemption.
When might full planning permission be required?
A new house, front dormer, larger extension, material change of use or development falling outside any exemption condition will generally require a planning application. A valid application is normally targeted for a decision within eight weeks, but requests for further information and appeals can make the process significantly longer.
Even where planning permission is not required, Building Regulations, Building Control requirements and fire-safety rules may still apply. Protected structures and properties in architectural conservation areas can also be subject to additional restrictions.
Ask your local planning authority to confirm the position for your particular property. An architect, architectural technologist, planning consultant or engineer may also be appropriate depending on the project.
Find trusted builders and trades in Ireland
Once your planning status, drawings and project requirements are clear, Trade Source IRE helps homeowners, landlords, businesses and developers find suitable trade professionals throughout Ireland.
Whether you need trusted builders in Ireland for an extension or attic conversion, or electricians, plumbers, carpenters, roofers and insulation contractors for the next stage, you can browse trades across Ireland or submit your project details.
Contractors are reviewed before joining the Trade Source IRE network. Customers should still compare detailed written quotations and confirm each contractor’s insurance, qualifications, certificates, references and suitability for the proposed work.
This article provides general information and should not be treated as professional planning or legal advice.
Frequently asked questions
What is the extension exemption in Ireland in 2026?
A rear extension may qualify as exempted development where the total relevant extension area does not exceed 45 square metres and every other condition is satisfied.
Do I need planning permission for a garden room in Ireland?
A side or rear shed, store, office or gym may qualify for an exemption within the combined 30 square metre limit, but conditions apply and separate living accommodation is not automatically permitted.
Is a dormer exempt from planning permission in Ireland?
Certain dormer roof extensions and windows to the side or rear may qualify up to 30 cubic metres when all statutory conditions are met. A front dormer is not covered by that exemption.
Does exempted development still have to meet Building Regulations?
Yes. Planning exemption and Building Regulations are separate matters. Building Control and fire-safety requirements may still apply.
Information sources
- Department of Housing — 2026 planning exemptions regulations
- Department of Housing — S.I. No. 338/2026 overview
- Irish Statute Book — S.I. No. 338/2026
- Department of Housing — Dormer roof extensions, S.I. No. 344/2026
- Irish Statute Book — S.I. No. 344/2026
- Citizens Information — Planning permission for altering your house
- Citizens Information — Planning permission in Ireland