Roof Drainage Design Guide

Location of drains 5.

Roof drainage design guide.

Select number of roof drains and calculate the roof area sloped to each drain. Size vertical storm drainage piping. Volume of expected rainfall. Ipc provides four steps to size the roof drains on a building.

Size horizontal storm drainage piping. Maximum pipe flow. Safety load requirement 8. Type of roof construction 2.

Inspect the current roof drain s and the drain line through the building for leaks and assure that the materials are. Determine leader or pipe size. Design assistance services are offered as a courtesy to the roofing design professional and contractors to ensure the project s success. Structural design of the roof and roof load.

2 3 4 5 6. In the design and detailing of a roof drainage system consideration must be given to a range of factors such as. The location and degree to which. Roof load requirement 7.

When selecting a roof drain note. The greater the slope the less water build up and thus roof load. First and foremost be sure to comply with all local plumbing codes. From there consider the following.

Properly designed roof drain must have the following features. 2 3 4 5 6 and 8 in. Secondary drainage shall be provided through the use of sidewall scuppers or internal roof drains. Determine 100 year 1 hour rainfall rate used for location of building.

In either case the discharge shall be located so that it is readily visible by building occupants. Pleasing dome shape with a low profile and adequate free drainage area corrosion resisting dome material effective debris protection overflow drainage to allow drainage during debris build up gravel stop positive flashing clamp seepage control channels. Developing the design criteria for a roof drainage plan that will perform with the roofing system to drain the roof is critical priorto the bid process and roof system installation. Calculate the total roof area by multiplying its length by width.

The sizing of the roof drainage system must consider all components. Rainfall intensity roof catchment area gutter size capacity gutter fall gutter outlets sumps rain heads nozzles downpipe size quantity and placement overflow consideration material. To select the proper roof drain the following information must be known. The rain storm the flow of rainwater on the roof surface the ability of the roof drain to move the water from the roof to the piping the vertical piping the horizontal piping and the connection to the point of discharge.

Inspect the roof surface and roof drains on a regular schedule to find and clear away any debris clogging the drains. Roofs inevitably serve as temporary rainwater reservoirs. Desired rate of drainage 6. Step by step instructions step 1.