Roof Drain Sizing

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.

Roof drain sizing.

Product name manufacturer color bolt hole style lip to lip bolt to bolt 180 bolt to bolt bolt holes type of bolt used material. For example in the u k. Conventional gutter systems such as those used on most houses are suitable for some low slope roofs. And 4 area handled by each drain.

For the purposes of this appendix the following metric conversions are applicable. The result is the number of drains needed. Or 12 drains required. Take the roof s total square footage and divide by the total square footage handled by one drain.

And then determine from the chart below how many roof drains you require. The four things you will need to know are. Click the table headings to sort by that column. When sizing roof drains the limiting factor for the amount of water each drain will carry away is the size of leader therefore increasing leader size decreases the number of drains required.

Designers specify compliance with bs en 12056 3 2000 that includes a calculation for the allowable capacity of the rainwater pipes. 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. 3 size of leader required. Factors which affect proper roof drainage are deck slope drain size and placement of drains.

How to measure roof drain parts. The sizing of the roof drainage system must consider all components. Each 4 drain size in a 6 hourly rainfall area will accommodate drainage of 3 070 sq. Roof water drain types and sizing sizing a roof water drain.

Area roof will require 100 000 3070 32 5 or 33 roof drains for ideal drainage. 1 rate of precipitation. 1 in 25 4 mm 1 ft 305 mm 1 ft2 0 0929 m2 100 0 figure a101 1 example roof plan 4 a 101 2 solution. 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.

2 total area of roof. Therefore the 100 000 sq. The rain storm the flow of rainwater on the roof surface the ability of the roof drain to move the water from the roof to the piping the vertical piping the horizontal piping and the connection to the point of discharge. The first step in sizing a roof drain is to calculate the surface area of the roof that the.

The roof drain or gutter or drain piping or downspout leader size diameter other size constraints e g. Zurn makes it easy to size roof drains.