Class 1a building | Chalkline

A Class 1a building, under NCC 2022 Part A6 (Building Classification), is a single dwelling. The definition covers detached houses, terraces, row houses, townhouses, and villa units. Almost every residential builder’s work falls into Class 1a.

Class 1a sits within NCC Volume Two (Class 1 and 10 buildings), which references the ABCB Housing Provisions Standard 2022 as the DTS pathway. Volume One (Class 2 to 9 buildings) does not apply to Class 1a work, even when the property is part of a multi-unit subdivision, as long as each dwelling is a separate Class 1a unit.

Related classes that often pair with a Class 1a job:

Class 1b: a boarding house, guest house, or hostel with a total floor area up to 300 m² accommodating up to 12 persons. Different fire and amenity requirements apply compared with Class 1a.
Class 10a: non-habitable building or structure on the same site (private garage, carport, shed, retaining wall, free-standing pergola). A detached garage is Class 10a; an attached garage is part of the Class 1a building, but the garage-to-house separation still triggers Part H3 fire requirements.
Class 10b and Class 10c: outdoor structures (fences, masts, antennas, private bushfire shelters) on a Class 1 property.

The classification determines which NCC parts and Housing Provisions sections apply. A misclassified job, for example calling a small boarding house “Class 1a” when it has 13 occupants and so is Class 1b, is a certifier-level compliance breach. The PCA (principal certifying authority) confirms the classification on the building permit or development approval.

Also known as: single dwelling, detached house, terrace house, townhouse, villa.

Category: NCC classification / residential.

Related

See also

Related articles