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.
Roof drains per square foot.
Roof area the 3 inch rainfall will produce 18 700 gallons in one hour at the rate of 312 gallons per minute.
Round spee d catch basins.
Drainage pipe required minimum diameter.
0104 x r x a g p m.
The result is the number of drains needed.
For example a 3 inch per hour rainfall will build up to a 3 inch depth on a flat roof in one hour at the rate of 1 87 gallons per hour sq.
The downspout is the portion of the gutter that drains water away to a safe place on the ground.
And then determine from the chart below how many roof drains you require.
If you need help finding a drain ask our drain wizard or call to speak with our roof drain expert.
The number of roof drains shown should be verified with local code requirements.
Area roof will require 100 000 3070 32 5 or 33 roof drains for ideal drainage.
Each drain can handle 4 600 sq.
The drains should be equally spaced and located symmetrically about the roof.
Therefore the 100 000 sq.
The speed at which the rain collects at the drain.
0 cubic feet per second cfs peak runoff volume.
The roof drain calculator below is based on the maximum amount of rainfall in inches per hour of the hypothetical worst storm in the past 100 years and which has a two percent chance of occurring in any given year.
Gallons per minute r rainfall intensity inches hour a roof area square feet 0104 conversion factor g p m sq.
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.
Or 12 drains required.
Equals 32 6 or 33 drains required.
We also stock many of the top selling drains and parts onsite so most orders ship same day.
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Take the roof s total square footage and divide by the total square footage handled by one drain.
0 gallons 0 cubic feet.
Or 0312 gallons per minute sq.
For 1 one inch hr.
0 submit your design let nds evaluate and help you with preparation of your submittal drawings and specs.
This reveals that the minimum size for the leader pipe is 5.
Divided by the 4 600 sq.
The next step is to consult table 1106 3 figure 2 to learn the required size of pipe.
Measuring the square feet of the roof along with knowledge of local rainstorms is invaluable when.
They come in a variety of shapes tubes chains etc but their goal is to prevent gutters from overflowing and give water somewhere to go.
Divide total roof area by area found in step 3 to obtain the number of drains required example.
Each 4 drain size in a 6 hourly rainfall area will accommodate drainage of 3 070 sq.
Using a 10 000 sq.
