Stairs

Figure 2: Stair components

Stair design consists of two main elements - treads which are walked upon, and stringers which support the treads - as shown in Figure 2. Sizes are determined by calculating the stair rake and the individual number of treads that can fit in the space available. Formulae for calculating this are provided in the BCA¡§, and once results have been confirmed, hardwood sizes for the treads and stringers can be selected from Tables 1 and 2. The table data is based on load assumptions derived from AS1170.1¡Ù for: domestic and residential activities in self contained dwellings, walking track structures and areas where people may congregate (without obstacles for moving people). Specific parameters covering these situation include: 5.0kPa uniformly distributed load, 4.5kN concentrated load and 2.4kN line load.


Notes
1. Refer BCA Volume 1, Clauses D2.8 to D2.18
2. AS1170.1 - Permanent imposed and other actions, Standards Australia