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Designing Roof Drainage
Correct design of a roof drainage system is critical to the waterproofing of a building. This is a task that should only be carried out by a suitably qualified trade professional in accordance with the BCA and Australian Standards.
In the design and detailing of a roof drainage system, consideration must be given to a range of factors such as:
- rainfall intensity
- roof catchment area
- gutter size/capacity
- gutter fall
- gutter outlets (sumps, rain heads, nozzles)
- downpipe size, quantity and placement
- overflow consideration
- material selection and
- jointing
View information on the design of roof drainage systems:
- Download Office of Fair Trading Residential Gutters Quick Reference Installation Guide (174 KB)
- Download Using LYSAGHT® Roofing & Walling - Chapter 2 Design Preliminaries (1090 KB)
- Download Using LYSAGHT® Roofing & Walling - Chapter 6 Roof Drainage (541 KB)
- Download Gutter Overflow Leaflet (327 KB)
Downpipe Design
The downpipe size and spacing should be determined in accordance with AS/NZ3500.3.2:1998 National plumbing and drainage: Part 3.2: Stormwater drainage - Acceptable solutions.
