How Many Downpipes For Roof Area

Min number of downpipes roof catchment area.

How many downpipes for roof area.

A house in chicago has a roof whose actual drainage area is 1 000 square feet. This is because larger roofs require bigger volumes of water to be diverted away from them during periods of rainfall. Doubling the number of downspouts halves the required capacity for each. To calculate the minimum number of downpipes divide the roof catchment area by the allowable maximum catchment per downpipe.

Usually the size for the largest collection area on the roof is used to size downpipes throughout. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. The 6 in 12 pitch factor 1 1 multiplied by 1 000 yields an effective area of 1 100 square feet. Size downspouts to fit the gutter.

In some cases roof area m gutter flow litres sec roof area m downpipe at centre half round 76mm 0 7 34 0 8 38 112mm 1 8 86 2 6 125 squareflo 3 2 154 3 8 182 125 68mm downpipe 3 8 182 4 6 221 82mm downpipe 4 0 191 4 9 235 regency 4 2 202 4 7 226 highflo 5 4 258 6 0 289 stormflo. Select 100 x 50 rectangular downpipe. Sizing downpipes downpipes are sized for the areas that discharge into them. From figure 3 5 a in as nzs 3500 3 the maximum catchment per downpipe is 47m 2.

Downpipe fall fall fall fall fall roof pitch 45 figure 1 an example of a roof with a total plan area of 98 m. There are many possibilities for downpipe positions. Using clause e1 table 5 see figure 2 at a roof pitch. How many downpipes do you need.

Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed.