NCC 2022 Shower Floor Grading Requirements – IMPORTANT UPDATE

PCG previously published an article describing how NCC 2022 requires shower to have a fall in the floor to a waste at minimum 1:80 to maximum 1:50.

We wish to highlight the max 1:50 fall is presenting issues with shower designs and construction where a single floor waste is installed.

The issue is when complying with the min 1:80 grade on the longer floor plane, the minimum change in height required will exceed the max 1:50 grade on the shorter plane. This is based on the assumption the perimeter of the shower is all set at the same height, sloping to the central waste with equal diagonal cuts.

For example, a 1800mm long x 900mm wide shower cannot possibly have a single floor waste.

The easiest solution is to provide a linear drain at one end of the shower, or alternatively set the perimeter of the shower at different heights so that each floor plane is between 1:80 and 1:50.

Each floor plane is measured perpendicular from the wall to the waste and not along the diagonal cut.

Importantly, where the shower must comply with the ABCB Livable Housing Design Standard, the opening must be step-free and not provide a cross-fall. For Queensland applications please refer to the QDC MP 4.5 for stepdown options.