Wednesday 16 October 2019

Ask our Architect: Do we need planning permission to turn our garage into a house?

Architect's Clinic

An architect's inspection and opinion on compliance with building control would be beneficial. (Stock photo)
An architect's inspection and opinion on compliance with building control would be beneficial. (Stock photo)

Dermot Ryan

Query: We built our house in the country in 2006 and also built a garage to the same spec as the house with plumbing and electrics. My son now needs to live in it. Do we need planning permission or what should we do, as it is already kitted out with kitchen and bathroom?

Answer: When considering the construction of any building, the two main areas for statutory compliance are planning and building regulations, with the former posing the greater challenge in this instance. The response to what may seem like a straightforward question is very much dependant on the specific details of the situation.

An attached garage

As your house is in the countryside, I suspect the garage is a detached structure. However, if it is, in fact, attached to the rear or side of the house and has a floor area of less than 40sqm, its conversion to domestic use may be considered exempted development. This would, however, be on the assumption that the house has not been extended previously, in which case the conversion is considered an extension and is not to be used as an independent living unit.

A detached garage

If the garage is detached and was granted planning permission with the house, it would be important to check the conditions imposed at that time as it would not be unusual for the local authority to place restrictions on the nature and extent of its use. Restrictions may rule out independent living accommodation, commercial or business use.

Exempt Development

If planning consent has not been obtained, it's worth noting that an aggregate detached garage or shed area of up to 25sqm may be considered exempt from requiring permission if built to the rear or side of the house. This is provided it does not extend forward from the building line of the house and does not exceed 4m in height if it has a pitched roof (or 3m if it has any other roof type). However, exempted development of this type is only permitted if it is not lived in or used for keeping animals.

Retention Permission

Keeping the above scenarios in mind, and as you have already undertaken much of the conversion works, you will most likely require retention permission for change of use from garage to 'granny flat' to allow occupation by your son to be authorised.

Any permission is likely to restrict occupation to close family members only and sale or letting of the 'granny flat' as an independent living unit may also be restricted. It is also not unusual for local authorities to place a time limit on such use, after which the permission would expire.

Building Regulations

Once the planning status has been regularised, you will need to consider compliance with building regulations. You mention that the garage was built to the same specification as the house which is a necessary requirement for the space to be considered as habitable living accommodation.

Aside from the building fabric requirements, some critical areas to verify would be that fire escape requirements are met, that an accessible entrance and visitable WC is provided, that adequate ventilation is present and that all habitable rooms have at least the minimum ceiling height.

An architect's inspection and opinion on compliance with building control would be beneficial in establishing this.

If considering changes to your home, work with a registered architect. Find one near you on, the registration body for architects in Ireland.

  • Dermot Ryan is a registered architect and director of Pallas Architects;
  • Do you have a design dilemma? Email your problem to
  • Advice is for guidance only and readers are advised to seek professional assistance for any proposed project.

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