Under I1D1(2)(a), I1D4 applies to all Class 9b buildings, both enclosed and open. This means that it applies to theatres, open-deck spectator stands, sporting stadiums, and the like, wherever the public is seated to view an event.

I1D4(a) deals with the height difference between the floors supporting seats in a theatre and the like. The maximum slope of the floor of 1 in 8 is consistent with D3D11(2)(b).

This slope cannot be used in aisles required to be accessible by people with disabilities. In such a case, the maximum slope of the aisle is 1 in 14, as required by AS 1428.1.

The maximum gap of 125 mm stipulated in I1D4(a)(iii) is consistent with D3D14(1)(d).

Figures I1D4a and I1D4b illustrate methods of complying with I1D4(a) and (b).

It is often impractical to require the standard minimum width of a path of travel to an exit of one metre between rows of fixed seating. I1D4(c) allows a reduced width in such cases. This width is based on studies of movement between rows.

Distance between the seats should ordinarily be measured:

• with the seat in the up position if folding seats are used; or
• directly between the seats, as shown in Figure I1D4c.

I1D4(c) applies only where the public is seated on fixed seating to view an event.