Does a Garden Gym Need Building Regulations Approval in England? The 15 and 30 Square Metre Rules and the One-Metre Boundary Test

Planning permission and Building Regulations are separate systems. A garden gym that needs no planning permission can still need Building Regulations approval, and one that needs approval may not need planning permission. This guide covers the England position for a detached, single-storey garden building used as a gym, based on the Building Regulations 2010, GOV.UK and the Planning Portal. It is general information, not legal advice, and the equivalent rules for other nations are covered separately in our guides to Wales, Scotland and Northern Ireland.

What Building Regulations cover

GOV.UK explains that the Building Regulations 2010 apply to the construction and extension of buildings, and that many alterations also need approval, including electrical work, bathroom installations, heating systems and window or door replacement. The approval can come from local authority building control or a private registered approver. GOV.UK adds that separate rules apply in Scotland and Northern Ireland. The Planning Portal states that its outbuilding guidance relates to the planning regime for England and that policy in Wales may differ.

The exemption for small detached buildings

Schedule 2 of the Building Regulations 2010 lists classes of building that are exempt from the regulations. Class 6 covers small detached buildings, and the schedule text is marked as extending to England and Wales. Its conditions as summarised on the legislation.gov.uk page are:

• A detached single-storey building with a floor area not exceeding 30 square metres, which contains no sleeping accommodation, and which either has no point less than one metre from the boundary of its curtilage or is constructed substantially of non-combustible material.
• A detached building with a floor area not exceeding 15 square metres that contains no sleeping accommodation, with no boundary condition attached to that limit.

The Planning Portal describes the same thresholds in plainer terms: building regulations will not normally apply where the floor area is less than 15 square metres and the building has no sleeping accommodation, and for 15 to 30 square metres approval is not normally required if there is no sleeping accommodation and the building is either at least one metre from any boundary or built substantially of non-combustible materials.

What follows in practice for a gym

For a typical garden gym, three questions decide the outcome. The first is floor area: is it under 15 square metres, or between 15 and 30? The second is location: if it is over 15 square metres, is every point at least one metre from the boundary, or is the structure substantially non-combustible? The third is use: any sleeping accommodation takes the building outside these classes, so a gym that doubles as a spare bedroom does not qualify. Because the classes cover detached single-storey buildings, the Planning Portal notes that a new garage attached to an existing home would normally need approval, which indicates that attachment to the house takes a structure out of the small detached building class. Our guide to a home gym in a conservatory or glazed extension covers the extension class.

Exempt does not mean unregulated

An exemption from Building Regulations does not remove other requirements. Planning rules on height, position and coverage continue to apply; the Planning Portal lists limits such as a 2.5 metre height cap within two metres of a boundary and a rule against outbuildings forward of the principal elevation, and says a listed building’s curtilage needs planning permission. Electrical work is a separate question, covered in our guide to power for a garden or outbuilding gym in England. GOV.UK says work that uses someone registered with a competent person scheme does not need separate approval for the work covered.

Consequences of getting it wrong

GOV.UK states that the person doing the work could be prosecuted and fined if they do not comply with the Building Regulations, that authorities may require the owner to pay for fixing faulty work, and that without approval the owner will not have the certificates of compliance that may be needed when selling the home. See our guide to selling a house with a home gym fitted for what passes to a buyer.

Frequently asked questions

Is a 20 square metre garden gym exempt? Under Class 6 it can be, if it is detached, single storey, has no sleeping accommodation and is either at least one metre from the boundary or substantially non-combustible.

Does the one-metre rule apply to a 12 square metre gym? No boundary condition is attached to the 15 square metre class, but the building must still contain no sleeping accommodation.

Do these rules apply in Wales? The schedule is marked as extending to England and Wales, but the Planning Portal says Welsh policy may differ, so Welsh readers should check the Welsh guidance.

The bottom line

In England, a detached single-storey garden gym without sleeping accommodation is exempt from Building Regulations if it is under 15 square metres, or up to 30 square metres if it is either at least one metre from the boundary or substantially non-combustible. Attached structures and anything with sleeping accommodation fall outside the exemption, and planning and electrical rules continue to apply separately.

Sources

• legislation.gov.uk, “The Building Regulations 2010, Schedule 2: Exempt buildings and work”
• Planning Portal, “Is building regulations approval needed for an outbuilding?”
• Planning Portal, “Outbuildings: planning permission”
• GOV.UK, “Building regulations approval”