Roof Drain Sizing

Roof water drain types and sizing sizing a roof water drain.

Roof drain sizing.

For example in the u k. Each 4 drain size in a 6 hourly rainfall area will accommodate drainage of 3 070 sq. And then determine from the chart below how many roof drains you require. The roof drain or gutter or drain piping or downspout leader size diameter other size constraints e g.

1 rate of precipitation. 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. Conventional gutter systems such as those used on most houses are suitable for some low slope roofs. 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.

And 4 area handled by each drain. Therefore the 100 000 sq. 2 total area of roof. Or 12 drains required.

How to measure roof drain parts. 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. 3 size of leader required. The sizing of roof drains must be large enough to quickly carry away all water entering the roof drains.

Roof drain system and size the scuppers denoting the required head of water above the scupper for the structural engineer. Take the roof s total square footage and divide by the total square footage handled by one drain. The sizing of the roof drainage system must consider all components. For the purposes of this appendix the following metric conversions are applicable.

Product name manufacturer color bolt hole style lip to lip bolt to bolt 180 bolt to bolt bolt holes type of bolt used material. The result is the number of drains needed. 50 000 4 400 11 36. 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.

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. Area roof will require 100 000 3070 32 5 or 33 roof drains for ideal drainage. Click the table headings to sort by that column. The four things you will need to know are.

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