How Many Downpipes Do I Need For My Roof

Doubling the number of downspouts halves the required capacity for each.

How many downpipes do i need for my roof.

Downpipes should not serve more than 12 metres of gutter length for each downpipe. Storm damage how to spot a roof leak signs of roof damage signs that you need a new roof ice damming. Average catchment per downpipe roof catchment area. 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.

Rolls of felt are 36 wide x 144 long for 15 and 72 long for 30. Per downpipe 223 8 47 4 76m 2 five downpipes are required round up to the next whole number step 6. Choosing a contractor contractor checklist financing your roof re roof 101. Then use the information below to see what size gutter you need.

To calculate the average catchment per downpipe divide the roof catchment area by the number of downpipes. Calculate the number of outlets per run. It is the roof area the pitch of the roof and the number of drops downpipes coming down from outlets in the guttering around the building determine the flow we will need to know these to calculate the flow capacity for you. Determine the average catchment area per downpipe.

Frequency and positioning of outlets downpipes. If a roof s various drainage areas call for different size gutters go for the biggest one k style. November 29 2019 the number of downpipes you need will depend on the size of your roof and your chosen style of guttering. Also the various styles of guttering that are available have different flow rates.

Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage. 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 code limit is 150mm for dp s and 26 800 sq mm for flat eaves gutters. You can choose a downpipe size and calculate the number required and the corresponding eaves gutter size.

This is because larger roofs require bigger volumes of water to be diverted away from them during periods of rainfall. You do not want to put extra pressure on the system. 6 inch 7 960 square feet. How many rolls of felt will you need roofing felt is sold by the roll.

5 inch 5 520 square feet. The average roll of 15 pound roofing felt covers about 400 ft 2 or 4 squares while the average roll of 30 pound roofing felt covers about 200 ft 2 or 2 squares. Size downspouts to fit the gutter. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed.