A good rule to follow is to provide two roof drains for a total roof area less than 10 000 square feet.
Pto roof drain spacing.
The result is the number of drains needed.
To convert to an area for a 4 inch per hour rainfall to enter table 1108 1 do this.
For example in the u k.
The drainage coefficient is the design capacity of the drainage system and is typically expressed as a depth of water removed in 24 hours inches day.
The full flow capacity of a drain is not realized until the water reaches approximately 2 5 above the inlet in a four inch drain and 3 5 in a six inch drain.
Once the drainage system is determined the designer must ensure positive drainage by correctly positioning the roof drains.
Enter table 1108 1 until you find a diameter pipe that will carry 2 344 sq ft.
Intensive layered green roof intensive green roofs have a deeper soil depth therefore the roof drain enclosure height is typically 12 or more.
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.
Typical range 0 25 to 0 5 inches day.
2 500 4 x 3 75 2 344 sq ft.
Taper roof insulation to drain sumps using tapered edge strips.
If insulation thickness exceeds 1 taper 18 from the drain bowl.
50 000 4 400 11 36.
The international codes i codes are the widely accepted comprehensive set of model codes used in the us and abroad to help ensure the engineering of safe sustainable affordable and resilient structures.
An additional roof drain should be added for each 10 000 square foot area.
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.
Take the roof s total square footage and divide by the total square footage handled by one drain.
If insulation layer is 1 or less taper 12 from the drain bowl.
The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process.
Z110 green roof drains are available with enclosure heights ranging from 5 to 18 or as specified.
Mechanically fasten all tapers using two fasteners per board.
Each vertical drain must carry 2 500 sq ft of roof area at 3 75 inches per hour of rainfall.
The sizing of roof drains must be large enough to quickly carry away all water entering the roof drains.
The roof drain or gutter or drain piping or downspout leader size diameter other size constraints e g.
Or 12 drains required.
A minimum 4 inch vertical drain is required.
