An accurate calculation is essential for properly functioning plumbing.
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.
Note that i said the drain pipe must be sloped rather than the french drain.
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.
It is generally accepted that 1 4 per foot of pipe run is the minimum for proper pitch on a sewer line.
Pipes must slope slightly downhill to drain properly.
But there are other issues concerning pitch to keep in mind.
Usually 1 8 per foot is plenty for drainage this is the same as the commonly recommended 1 slope.
The roof pitch or slope factors for roof pitch are used to multiply or increase the rainfall rate if we are draining a sloped roof the roof drain or gutter or drain piping or downspout leader size diameter other size constraints e g.
Cleanouts in draining systems cleanouts provides access to the sewer for rodding.
Drain waste and vent pipe hanger spacing support of drain waste and vent dwv pipes.
Ss525 2006 code of practice for drainage of roofs.
In general plumbing codes require pipes less than 3 inches in diameter to slope a 1 4 inch per foot of run.
Larger lines such as 8 pipe actually require less pitch due to the larger circumference of the pipe.
Tips on calculating drain pipe slopes use the longest level possible for your application for the best accuracy when the bubble on a level is about 1 4 of the way past the line it is about a 1 4 slope.
Smaller pipes are more likely to experience blockages than larger pipes and therefore require a steeper slope.
According to the chart for 1 8 slope per 12 of pipe for 5 000 square feet of roof area with a 6 per hour of rainfall the required pipe size is 8.
The calculations below are meant for drainage from flat roofs where water are expected to spread over the entire flat roof during rain.
Slope of drain and waste pipes drainpipe sloping requirements vary according to the pipe s diameter.
All of your drain pipe with one exception must slope slightly downhill.
To size the vertical roof drain for the same parameters 5 000 square feet of room area and 6 per hour of rain consult table 1106 2 figure 3.
The flat roof must have sufficient slope to allow water to flow towards the roof outlets.
Sanitary drainage systems the purpose of a sanitary drainage system is to remove effluent discharged from plumbing fixtures and other equipment.
Laying drainage pipes is a job for professionals but diyers can try their hand at less extensive drainage systems.
