Roof Area Per Downpipe

Divide the main roof into catchments of this size and any left over area can be entered again to find a down pipe size for this smaller area.

Roof area per downpipe.

From figure 3 5 a in as nzs 3500 3 the maximum catchment per downpipe is 47m 2. Using clause e1 table 5 see figure 2 at a roof pitch. Select 100 x 50 rectangular downpipe. The program will calculate the most suitable circular and rectangular downpipe sizes.

Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Working out the size of your roof. The answers for downpipe size are in mm. Min number of downpipes roof catchment area.

To calculate the minimum number of downpipes divide the roof catchment area by the allowable maximum catchment per downpipe. The 6 in 12 pitch factor 1 1 multiplied by 1 000 yields an effective area of 1 100 square feet. A house in chicago has a roof whose actual drainage area is 1 000 square feet. Size downspouts to fit the gutter.

Roof length x half roof width x roof height 2 roof area. Sizing downpipes downpipes are sized for the areas that discharge into them. Determine minimum number of downpipes. Doubling the number of downspouts halves the required capacity for each.

Usually the size for the largest collection area on the roof is used to size downpipes throughout. The first thing you need to work out is the area of the roof that will collect rainfall which is known as the effective roof area. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. Choosing the right style of guttering downpipes.