AUST – HENDRY building surveyors advise that the Building Code of Australia in Part F1 ‘Damp and Weatherproofing’ contains clause F1.1 Stormwater drainage. The following explanation and illustration will enlighten the requirements for various situations.

Building Code of Australia: Clause F1.1 – Issue

What are the principles related to drainage systems for buildings? Can different requirements can apply depending on the nature of the building element being considered?

Building Code of Australia: Clause F1.1 – Explanation

AS 3500.3.2 provides design requirements for drainage systems. The code does not cover the effects of hail or the lack of regular maintenance. Trafficable roof areas, box gutters and terraces etc require drainage systems that can accommodate a 1:100 year return period for the region in which the building resides. Overflows of equal capacity must also be provided. Eaves gutters need only be designed for a 1:20 year return period provided when they overflow, water cannot enter a building. FP1.2 requires surface water to not enter a building for a return period of 100 years therefore carparks, etc. must be also drained for a 1:100 period. Stormwater must be directed to an appropriate outfall which is usually approved by the local authority. All components of the drainage system from capture areas to outfall must be correctly designed.

The following illustration from BCA Illustrated depicts typical drainage requirements.


BCA Illustrated

BCA Illustrated contains 10 illustrations (each containing an issue, explanation, references and an illustration) in Part F1 – ‘Damp and Weatherproofing’.

Building Legislation Table

Refer to our Building Legislation table for further information on the building certificate process including a fire safety audit.

Fire Safety Compliance: Essential Safety Measures

Refer to our Essential Safety Measures Identification Table for further information on individual essential safety measures including the Annual Statement.

Further Advice

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