How do you calculate the number of downspouts?
How do you calculate the number of downspouts?
- Measure the roof to get the watershed area, the area from which water will run off. Multiply length (peak to eave) by width to determine square footage.
- Find the rainfall intensity for your locale.
- Divide the inch per hour watershed of the roof by the 5-minute rainfall intensity.
- Size downspouts to fit the gutter.
How much roofing area does a downspout need?
It is based on the assumption that during a rainfall with an intensity of 1 inch per hour, each square inch of downspout can drain 1200 square feet of roof. If the intensity is doubled the downspout capacity is halved, or 600 sq. ft.; if it is tripled the capacity is one third, and so on. Area drained per sq.
How much space do you need between downspouts?
If we have to sum it up in a single rule, gutters need a downspout around every 30 to 40 feet. For most homes, this means installing spouts at either end of a gutter section.
How do you calculate gutters and downpipes?
Multiply the drainage area by the roof-pitch factor and rainfall intensity to find out the adjusted square footage. Then use the information below to see what size gutter you need. (If a roof’s various drainage areas call for different size gutters, go for the biggest one.)
How many downpipes do I need calculator?
To calculate the minimum number of downpipes, divide the roof catchment area by the allowable maximum catchment per downpipe. To calculate the average catchment per downpipe, divide the roof catchment area by the number of downpipes.
How do you layout a downspout?
Plan Where the Gutters and Downspouts Will Go Downspouts are generally placed on both ends of a row of gutters, but a long row may need several downspouts in between. On a multi-story home, the downspouts need to connect with lower gutters to create a maze of drainage around the house.
How far should your downspouts be extended from house?
4 to 6 feet away
As mentioned above, the water should be diverted at least 4 to 6 feet away from the house. If a home has basement walls, it should be at least 6 feet away. The furthest away from the foundation the better. Putting gravel or rocks at the end of the downspout to avoid erosion is a great idea.
How long is a 2 story downspout?
about 24-26 feet long
Then measure downspout lengths too – typically about 14LF for first floor plus about 10-12 additional feet for each story above that, per downspout – so your second-story roof downspouots would likely be about 24-26 feet long, including bends to reach back to house corner and runout at the bottom.
How many roof drains do I need calculator?
Take the roof’s total square footage and divide by the total square footage handled by one drain. The result is the number of drains needed. For example: 50,000 / 4,400 = 11.36; or 12 drains required.
