Once the drainage system is determined the designer must ensure positive drainage by correctly positioning the roof drains.
Pto roof drain spacing.
Z110 green roof drains are available with enclosure heights ranging from 5 to 18 or as specified.
The roof drain or gutter or drain piping or downspout leader size diameter other size constraints e g.
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.
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.
If insulation layer is 1 or less taper 12 from the drain bowl.
If insulation thickness exceeds 1 taper 18 from the drain bowl.
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 required parameters for the drain spacing calculator with typical values for the upper midwest and a reference diagram are as follows.
Intensive layered green roof intensive green roofs have a deeper soil depth therefore the roof drain enclosure height is typically 12 or more.
The result is the number of drains needed.
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.
An additional roof drain should be added for each 10 000 square foot area.
Take the roof s total square footage and divide by the total square footage handled by one drain.
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.
A good rule to follow is to provide two roof drains for a total roof area less than 10 000 square feet.
The sizing of roof drains must be large enough to quickly carry away all water entering the roof drains.
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.
Mechanically fasten all tapers using two fasteners per board.
To convert to an area for a 4 inch per hour rainfall to enter table 1108 1 do this.
Enter table 1108 1 until you find a diameter pipe that will carry 2 344 sq ft.
2 500 4 x 3 75 2 344 sq ft.
Each vertical drain must carry 2 500 sq ft of roof area at 3 75 inches per hour of rainfall.
Designers specify compliance with bs en 12056 3 2000 that includes a calculation for the allowable capacity of the rainwater pipes.
Typical range 0 25 to 0 5 inches day.
50 000 4 400 11 36.
Or 12 drains required.