Sole-occupancy unit (SOU)

A sole-occupancy unit (SOU) is an NCC-defined term for a room or other part of a building occupied by one (or one joint) owner, lessee, tenant, or occupier to the exclusion of any other. In plain terms, it is a space under one party’s exclusive use, while common areas (hallways, lifts, gardens) are shared (verified 2026-05-25, NCC Schedule 1 definitions).

What counts as an SOU. It depends on the building class:

A Class 1a house is a sole-occupancy unit.
Each apartment in a Class 2 building is an SOU (the unit you own or rent, as distinct from the common property).
A room or suite in a Class 3 hotel or motel is an SOU.
A shop in a Class 6 shopping centre, or a tenancy in a Class 5/6/7/8/9 building, is an SOU.

Why it matters: the SOU is the NCC’s unit of separation. Many of the Code’s most important requirements apply between sole-occupancy units, not within them. The fire-resisting and sound-insulating construction the NCC requires for an apartment is about the walls and floors separating one SOU from another (and from common areas). When a clause says a requirement applies “between sole-occupancy units”, the SOU boundary is exactly where you build it.

For a builder:

Identify the SOU boundaries early. In a Class 2 build, the party walls and inter-tenancy floors between apartments are SOU separations, and they carry the fire (fire door, FRL) and sound-insulation requirements.
Read “between SOUs” literally. The requirement is at the boundary between units, so the rating must be achieved at that wall or floor, not somewhere convenient.
Class drives the rest. What is an SOU and what separation applies flows from the building class.

Also known as: SOU, sole occupancy unit.

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