Detached Auxiliary Dwellings
The Planning and Development (Exempted Development (Act of 2000)) Regulations 2026 provide for a new exemption for an auxiliary habitable dwelling to allow for the addition of a detached habitable accommodation linked to the services of the principal house, which may be between 32 and 45 square metres. Hereafter, such development is referred to as an auxiliary dwelling.
Irrespective of the exemption from planning permission, an auxiliary dwelling must comply with Building Regulations, in the same manner as any new dwelling. The normal building control process is required e.g. the submission of a Commencement Notice (CN) with Additional Documentation, including the nomination of a Design Certifier, Assigner Certifier, competent builder and a Certificate of Compliance on Completion (CCC).
The Department has prepared an Information Note providing general information on how an auxiliary dwelling can comply with the requirements of the Building Regulations and Building Control Regulations. This Information Note can be accessed here.
Subdivision of a Dwelling
The Planning and Development (Exempted Development (Act of 2000)) Regulations 2026 provide for a new exemption for sub-division of a principal dwelling to allow for the creation of up to 1 additional self-contained unit within the existing building envelope, with a minimum floor area for each subdivided unit of 32 square metres.
The subdivision of a dwelling into 2 dwellings, whether by horizontal separation or vertical separation constitutes a material change of use to which the Building Regulations (S.I. No. 497 of 1997, Article 13) relate. In respect of other works carried out in connection with the subdivision, Building Regulations apply in so far as they apply to works to an existing building e.g material alteration etc., and prohibit any work that would cause a new or greater contravention.
In relation to Building Control Regulations, a Fire Safety Certificate is required for the subdivision of a dwelling horizontally, creating two flats one above the other. However, where the subdivision of a dwelling is vertical e.g. dividing an existing dwelling, creating two dwellings side-by side (semi-detached houses), a Fire Safety Certificate is generally not required, unless a shared internal access/egress route, such as a common lobby, is created.
In all cases where a dwelling is subdivided, the normal building control process is required e.g. the submission of a Commencement Notice (CN) with Additional Documentation, including the nomination of a Design Certifier, Assigner Certifier, competent builder and a Certificate of Compliance on Completion (CCC).
Further information on the subdivision of dwellings is available in Bringing Back Homes – Manual for the Reuse of Existing Buildings which is available here.
