How Many Downpipes For Roof Area Uk

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 110mm 11 1 534 12 4 598 160mm 12 5 601 14 0 673 downpipe at end half.

How many downpipes for roof area uk.

Because this is only one half of the roof we will need to double this number to find the entire roof area 121 45m. Calculate the effective catchment area x to be drained from the following table. From figure 3 5 a in as nzs 3500 3 the maximum catchment per downpipe is 47m 2. Min number of downpipes roof catchment area.

Also the various styles of guttering that are available have different flow rates. You can choose a downpipe size and calculate the number required and the corresponding eaves gutter size. 8 7m x 6 98m 60 73m. Select 100 x 50 rectangular downpipe.

The code limit is 150mm for dp s and 26 800 sq mm for flat eaves gutters. To calculate the minimum number of downpipes divide the roof catchment area by the allowable maximum catchment per downpipe. Determine minimum number of downpipes. Frequency and positioning of outlets downpipes calculate the number of outlets per run.

The number of downpipes you need will depend on the size of your roof and your chosen style of guttering. Floplast guide to guttering and roof area. As you can see with an effective area of 40m 2 there will be no issue using any of these systems and configurations. A rainwater downpipe is a pipe that is used to direct rainwater away from a building typically from roof guttering to a drainage system it is sometimes also referred to as a downspout drain spout roof drain pipe or leader.

So for our example the half roof area is as follows. The roof slope height is 6 98m. There is no limit to downpipe size or eaves gutter size. The flow rate is the number of litres of water that they re able to divert per second.

To select the size of the classical rainwater system the following method should be used. The building regulation s part h drainage and water disposal requires that adequate provision is made for rainwater to be carried from the roof of buildings. Lg 10 133 therefore reduction factor 0 86 d 0 1 gutter capacity x reduction factor 2 84 x 0 86 2 44 l s therefore the proposed system is suitable. Design area effective area 5 x 10 x 1 29 64 5m run off 64 5m x 0 022 l s per m 1 42 l s from chart 125 x 100 gutter with 76 ø downpipe appears suitable but check.

This is because larger roofs require bigger volumes of water to be diverted away from them during periods of rainfall. However if our effective roof area were 50 m 2 then we would not be able to use a level half round gutter with a stop end outlet ie the downpipe at one end of the gutter rather than in the middle. Table 1 calculation of area drained type of surface effective design area m 1 flat roof plan area of relevant portion 2 pitched roof 30 pitched roof 45 pitched roof 60 plan area of portion x.