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Do You Need Planning Permission for a Garden Sauna in Ireland? The 30 sqm Rule Explained

Key takeaways

  • The exempted development allowance for garden structures in Ireland increased from 25 to 30 square metres on 27 July 2026. Most online guidance has not caught up.
  • The 30 square metres is a combined total for all such structures in the curtilage, not per structure. An existing shed or garage eats into it.
  • You must retain at least 25 square metres of private open space to the rear or side after building.
  • Height limits: 4 metres for a tiled or slated pitched roof, 3 metres for any other roof.
  • The structure must be incidental to the enjoyment of the house and not used for human habitation. A garden sauna sits comfortably inside that.

 

If you searched this question before the end of July 2026, you got a different answer than the one that applies now, and most of the internet has not noticed yet.

On 27 July 2026 the Irish exempted development rules changed. The allowance for sheds, stores, garages and similar structures within the curtilage of a house rose from 25 square metres to 30. For anyone planning a garden sauna, that is five extra square metres of room to work with, and for anyone who already has a shed, it may be the difference between an application and no application.

Here is what the rule actually says, and what it means for a sauna.

What changed, precisely

The Planning and Development (Exempted Development (Act of 2000)) Regulations 2026 (S.I. No. 338 of 2026), signed on 16 July 2026 and in operation from 27 July 2026, substituted Class 3 of Part 1 of Schedule 2 of the Planning and Development Regulations 2001. Class 3 covers “the construction, erection or placing within the curtilage of a house of any tent, awning, shade or other object, greenhouse, garage, store, shed or other similar structure.” A garden sauna falls within that description. The conditions, as amended:
Condition The limit
Position Not forward of the front wall of the house
Total area All such structures together must not exceed 30 square metres (previously 25)
Private open space Must not reduce private open space to the rear or side, reserved for the occupants, below 25 square metres
External finishes, side of house Must conform with those of the house where tiled or slated
Height, tiled or slated pitched roof 4 metres
Height, any other roof 3 metres
Use Not for human habitation, not for keeping animals, and for no purpose other than one incidental to the enjoyment of the house
Source: S.I. No. 338/2026, Irish Statute Book

The three that catch people out

It is a combined total, not an allowance per building. The 30 square metres counts every structure of this class already in your curtilage. An existing 12 square metre shed leaves you 18. This is the single most misunderstood part of the rule and it has not changed, only the ceiling has.

You must keep 25 square metres of open space. Separate from the 30, and measured after the sauna is in. On a compact site this is the limit that bites first, not the floor area.

Height is measured for the whole structure. A pitched, tiled or slated roof buys you 4 metres. Anything else, including most flat and single-pitch modern cabin designs, is capped at 3.

Is a sauna "incidental to the enjoyment of the house"?

Yes, on the ordinary reading. The condition exists to stop exempted structures being used as separate dwellings or for commercial or agricultural purposes. A private garden sauna used by the household is incidental use in exactly the intended sense.

Two things do change the answer. Running it as a business, for example a public or bookable sauna, is not incidental use and is a different application entirely. And sleeping in it makes it habitation.

Where exemption does not apply

Exempted development is not universal. Check before you rely on it if your property is a protected structure, sits within an Architectural Conservation Area, or is subject to conditions attached to the original planning permission for the house. Coastal and other environmentally designated sites can carry their own restrictions. Where you are unsure, your local authority can give a formal answer through a Section 5 declaration.

Exempted development is not building control

Separate systems. Exemption from planning does not remove obligations under Building Regulations, and it says nothing about electrical safety. A sauna heater is a substantial electrical load and the installation should be carried out and certified by a Registered Electrical Contractor.

The practical sequence

  1. Measure what Class 3 structures already exist in your curtilage and total their floor area.
  2. Subtract from 30 to find what remains.
  3. Measure the private open space that will remain after the sauna is in. It must be at least 25 square metres.
  4. Check the roof type against the height limit.
  5. Confirm your property is not a protected structure or in an ACA, and check the original planning conditions for the house.
  6. If anything is unclear, apply for a Section 5 declaration.
  7. Arrange the electrical installation with a Registered Electrical Contractor.
Based on S.I. No. 338 of 2026 as in operation from 27 July 2026. Planning is site-specific. Confirm with your local authority before building.

Frequently asked questions

Do I need planning permission for a sauna in Ireland?

Usually not, if it stays within the Class 3 exempted development conditions: 30 square metres combined for all such structures, 25 square metres of private open space retained, within the height limits, behind the front wall of the house, used incidentally.

Has the 25 square metre rule changed?

Yes. It increased to 30 square metres on 27 July 2026 under S.I. No. 338 of 2026.

Does my existing shed count toward the limit?

Yes. The 30 square metres is the combined total of all such structures in the curtilage, including anything already there.

How tall can a garden sauna be in Ireland?

4 metres with a tiled or slated pitched roof, 3 metres with any other roof.

Can I run a public sauna from my garden under exempted development?

No. Commercial use is not incidental to the enjoyment of the house and requires planning permission.

What if I am not sure whether my sauna is exempt?

Apply to your local authority for a Section 5 declaration, which gives a formal determination on whether the development is exempted.

Next step

Explore Outdoor Saunas · Talk to a Design Consultant

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Garden Sauna Planning Permission in the UK · Buying vs Building a Sauna

This article is part of The Complete Guide to Home Saunas, Celsium’s full guide to choosing, building and owning one.

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