BU511 Residential roof drainage design (2009)

A key component of residential design and construction is a roof that not only keeps the building weathertight but efficiently collects and drains the rainwater that falls on it.

This bulletin covers design principles for roof drainage for residential buildings that can be applied across a range of roof styles and cladding types.

The bulletin covers:

• key design considerations, including rainfall, wind and wind pressure, roof geometry, roof slope, structural movement, roof material span and maintenance
• drainage mechanisms and water collection, including valley gutters, flashings, changes of slope and penetrations
• maintenance.