Roof Gutter Drain Pipe Size

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

Roof gutter drain pipe size. Determine 100 year 1 hour rainfall rate used for location of building. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Or less in diameter the piping will be larger in diameter than the roof drain. The downspout size must suit the bottom width of the gutter.

Following this logic it is possible that for roof drains 6 in. For larger roof drains the pipe may be smaller such as a 10 in. Digging a trench that deep is only practical when the end of the pipe drains into a dry well or is connected to an existing drain line. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour.

Roof drain connected to an 8 in. Lay out the pipe lengths and fittings. The only guaranteed way to keep the pipe from freezing is to bury it below the frost line which ranges between 32 and 48 inches in most areas of the snow belt. The gutter outlet capacity should suit the downspout capacity.

This wizard makes it easy to calculate the roof design area by providing various shape calculations and the calculation for vertical walls area per international plumbing code ipc. Buried or underground roof drainage downspout defects clogging overflowing holes corrosion leaks that cause wet basements or crawl areas proper installation of buried downspout extensions proper installation of french drains seepage pits at flat sites gutter downspout defects cause wet basements crawl areas questions answers about installing maintaining repairing buried roof. Use this downspout extension to divert water away from the foundation or connect to drainage pipe and catch basin to control drainage. Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage.

The flexible design easily bends and holds its shape and can be extended from 25 in. Offset of more than 10 ft 3 0 m can affect drainage capacity. Select number of roof drains and calculate the roof area sloped to each drain. Smacna s new downspout and gutter sizing calculator enables the user to manually enter the design area of the roof or use the design area wizard for the calculation.

Ipc provides four steps to size the roof drains on a building. Roof drain connected to a 6 in. Size downspouts to fit the gutter. If a roof s various drainage areas call for different size gutters go for the biggest one k style.

For example a 4 in. Size horizontal storm drainage piping. Then use the information below to see what size gutter you need. Featuring durable vinyl construction this extension can be buried bent or connected to additional sections.