Roof Drainage Design Guide

Location of drains 5.

Roof drainage design guide.

To select the proper roof drain the following information must be known. Size vertical storm drainage piping. Step by step instructions step 1. Rainfall intensity roof catchment area gutter size capacity gutter fall gutter outlets sumps rain heads nozzles downpipe size quantity and placement overflow consideration material.

The location and degree to which. 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. Determine leader or pipe size. Roof load requirement 7.

Calculate the total roof area by multiplying its length by width. 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. 2 3 4 5 6 and 8 in. Size horizontal storm drainage piping.

Properly designed roof drain must have the following features. Secondary drainage shall be provided through the use of sidewall scuppers or internal roof drains. Maximum pipe flow. Determine 100 year 1 hour rainfall rate used for location of building.

Type of roof construction 2. Design assistance services are offered as a courtesy to the roofing design professional and contractors to ensure the project s success. Desired rate of drainage 6. The greater the slope the less water build up and thus roof load.

Safety load requirement 8. Secondary or emergency roof drainage is required wherever the buildup of water is detrimental to the roof structure. First and foremost be sure to comply with all local plumbing codes. Volume of expected rainfall.

From there consider the following. Select number of roof drains and calculate the roof area sloped to each drain. In the design and detailing of a roof drainage system consideration must be given to a range of factors such as. 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.

Ipc provides four steps to size the roof drains on a building. When selecting a roof drain note. Inspect the current roof drain s and the drain line through the building for leaks and assure that the materials are. 2 3 4 5 6.

In either case the discharge shall be located so that it is readily visible by building occupants. Calculate total roof area. Inspect the roof surface and roof drains on a regular schedule to find and clear away any debris clogging the drains. Structural design of the roof and roof load.