Building a Garden Gym or Outbuilding in Northern Ireland: Planning Class D and the Building Regulations Exemptions

Guidance on garden gyms and garage conversions is usually written for England, and this site already covers England, Scotland and Wales separately. Northern Ireland has its own planning order and its own building regulations, so the thresholds differ. This article summarises the two instruments that matter most for a detached garden gym: the Planning (General Permitted Development) Order (Northern Ireland) 2015 and the Building Regulations (Northern Ireland) 2012. It applies to Northern Ireland only. The legislation.gov.uk text showed no known outstanding changes at the time of reading, but the local council decides any borderline question.

Two separate regimes

nidirect explains that if a person develops land without the necessary planning permission the council may force them to put things right later. Building regulations are separate: nidirect says they protect safety, health and welfare in and around buildings and are administered by local councils. A building can be free of one regime and caught by the other.

Planning: permitted development Class D

Under the 2015 Order, Part 1 covers development within the curtilage of a dwellinghouse. Class D permits the provision within the curtilage of any building or enclosure, swimming or other pool required for a purpose incidental to the enjoyment of the dwellinghouse. A detached garden room or gym for the household is the kind of building that question concerns, but the Order does not list gyms, and whether a specific use is incidental is a matter for the council. nidirect notes that a formal ruling can be sought by applying to the council for a Certificate of Lawful Use or Development, which carries a fee.

Development is not permitted under Class D if:

• the total ground area covered by buildings or enclosures within the curtilage, other than the original dwellinghouse, would exceed 50% of the curtilage (excluding the original dwellinghouse’s footprint);
• any part would be forward of a wall facing a road that forms the principal or a side elevation of the original dwellinghouse;
• the building or enclosure would exceed 4 metres in height;
• within 2 metres of the curtilage boundary the eaves height would exceed 2.5 metres;
• any part would be within 3.5 metres of a curtilage boundary with a road opposite the rear wall of the dwellinghouse;
• it would include a deck, balcony, veranda or other raised platform;
• it would involve a microwave antenna;
• it would be for use as a dwellinghouse; or
• it is within the curtilage of a listed building, unless listed building consent has already been granted.

The prohibition on use as a dwellinghouse matters for any gym that would also provide sleeping or living accommodation, since that falls outside this class.

Protected areas

The Order adds tighter limits in sensitive locations. In a World Heritage Site, National Park or area of outstanding natural beauty, Class D does not permit buildings, enclosures and pools more than 20 metres from any wall of the dwelling if together they would cover more than 10 square metres. In a conservation area, World Heritage Site, National Park or area of outstanding natural beauty, no part of the building may sit between a wall forming the principal or a side elevation of the dwelling and the curtilage boundary. nidirect adds that permitted development rights are restricted for listed buildings, conservation areas and Areas of Outstanding Natural Beauty, and that planning permission is needed for certain works there.

Building regulations: the small detached building exemption

Schedule 2 of the Building Regulations (Northern Ireland) 2012 lists classes of exempted buildings. Class 7 covers small detached buildings. Under it, an exempted building is:

• a detached single-storey building with a floor area not exceeding 30 square metres, containing no sleeping accommodation, that is either constructed substantially of non-combustible material or at no point less than 1 metre from the nearest point of a dwelling, the nearest part of a road, or the nearest point of the boundary of the land; or
• a detached single-storey building with a floor area not exceeding 15 square metres, containing no sleeping accommodation, that is not less than 1 metre from a dwelling.

A typical timber garden gym under 30 square metres, one storey, no bed and set at least 1 metre back from the dwelling, road and boundary fits the first limb. A larger building, a two-storey building, one attached to the house or one with sleeping accommodation does not fit Class 7 and would need to be discussed with the council’s building control. The exemption from the regulations does not itself say anything about planning, so Class D still has to be checked.

A practical sequence

1. Measure the curtilage and the proposed footprint, height and eaves, and check the 50% coverage, 4 metre height and 2.5 metre eaves limits.
2. Check whether the property is listed or in a conservation area, National Park, World Heritage Site or area of outstanding natural beauty.
3. Check the Class 7 figures: single storey, 30 square metres or less, no sleeping accommodation, and the 1 metre distances or non-combustible construction.
4. Ask the council’s planning office and, where relevant, building control before starting, and consider a Certificate of Lawful Use or Development if certainty is needed.

Frequently asked questions

Does a garden gym need planning permission in Northern Ireland?

It can be permitted development under Class D if it meets every condition, but the council decides whether the use is incidental to the enjoyment of the dwelling.

Is a 25 square metre gym exempt from building regulations?

Under Class 7, a detached single-storey building up to 30 square metres with no sleeping accommodation is exempt if it meets the distance or non-combustible material condition.

The bottom line

In Northern Ireland a detached garden gym may be permitted development under Class D if it stays within the coverage, height, eaves and location limits and is not a dwelling. It may also be exempt from the building regulations under Class 7 if it is a detached single-storey building of no more than 30 square metres with no sleeping accommodation and the required separation or construction. Because the council decides borderline questions, asking it first is the safest step.

Sources

• legislation.gov.uk, “The Planning (General Permitted Development) Order (Northern Ireland) 2015”, Part 1, Class D
• legislation.gov.uk, “The Building Regulations (Northern Ireland) 2012, Schedule 2: Classes of exempted buildings”
• nidirect, “Planning permission – when to apply”
• nidirect, “Getting help with planning”
• nidirect, “What Building Regulations protect”