The roof drainage outlets and rainwater downpipes are calculated based on the design principles for gravity drainage systems established in ss525 2006 code of practice for drainage of roofs.
Roof drain pipe slope.
According to plumbing code drain pipe has to be sloped a minimum of 1 4 inch per foot and a maximum of three inches per foot or vertical.
The following diagram lays out the different terms that are used in the calculator.
Drain pipe slope calculator.
A slope of less than 1 4 inch per foot will cause constant drain clogs and a slope of more than three inches will allow the water to drain without the solids.
Calculating the slope of your drain pipe is easy.
How to use the calculator.
Note that i said the drain pipe must be sloped rather than the french drain.
Larger lines such as 8 pipe actually require less pitch due to the larger circumference of the pipe.
The maximum height of the roof drains shall be a height to prevent the depth of ponding water from exceeding that for which the roof was designed as determined by section 1101 12 1.
But there are other issues concerning pitch to keep in mind.
This drain pipe slope calculator will calculate the slope and total drop fall of a drainage pipe over a specified length of pipe.
The best type for the application depends on several factors such as the size and slope of the roof the desired appearance and how much regular maintenance the drain system might need.
Roof drains for flat or low slope roofs come in a few standard types.
Cleanouts in draining systems cleanouts provides access to the sewer for rodding.
Usually 1 8 per foot is plenty for drainage this is the same as the commonly recommended 1 slope.
The calculations below are meant for drainage from flat roofs where water are expected to spread over the entire flat roof during rain.
It is generally accepted that 1 4 per foot of pipe run is the minimum for proper pitch on a sewer line.
Sanitary drainage systems the purpose of a sanitary drainage system is to remove effluent discharged from plumbing fixtures and other equipment.
Drain waste and vent pipe hanger spacing support of drain waste and vent dwv pipes.
While vent piping generally runs straight to the building s roof in a vertical path drain and waste branch pipes must slope toward main drainpipes which slope toward main drain outlets.
All of your drain pipe with one exception must slope slightly downhill.
I downloaded installed and tried out harmer drainage s free roof drainage calculator for a flat roof choosing a roof drain product line which has implications of drain pipe diameter and thus capacity geographic area the tool can plug in rainfall rates for the u k and i used an assumed a roof area of 10x10m 100 m2.
