Roof Drainage System Design

A siphonic roof drain utilizes siphoning as a drainage mechanism resulting in drainage that is faster than that on any other type of roof drain.

Roof drainage system design.

There are various approaches that can accomplish this balancing act but each offers its own advantages disadvantages depending on a number of factors. Hence this is by far the most common roof drainage situation. Green roof solutions offers many different drainage layer options depending on system goals regarding water retention. To design a sloped or flat roof drainage system we need to know the anticipated maximum rainfall rate and the flat or projected roof area.

A typical commercial or multifamily residential building will utilize one of the following types of primary roof drainage. Functioning drainage system for steep slope roofs is to maintain a minimum roof slope. The most critical role of the drainage layer is to provide an adequate flow of water off the roof during and after rainfall. For most dwellings you ll find that gutters range in size from approximately 100mm diameter to 150mm diameter assuming gutters with a half round section profile and downpipes range from approximately 60mm diameter to 90mm diameter assuming circular downpipes.

Design considerations to keep in mind. Roof drainage is one of the fundamental considerations of building design. From the very dawn of building construction it has been necessary to incorporate some method of gathering and discharging rainwater from the roof of a structure. Typically a steep slope roof slope is equal to or greater than 3 inches of rise per 12 inches of run 25.

Establishing a minimum slope is critical because most steep slope roofing as. The design event used for sizing a roof drainage system will therefore not normally come out of a clear blue sky and then end equally suddenly but will have been preceded by a period of less intense rainfall. It is important for architects plumbing engineers and civil engineers to work together to design a system that will properly drain rainwater from a building and site. Please see roof drainage calculations for a detailed answer to your question.

I examined several roof drainage calculators and tables to see what they tell us.