Roof Drainage Design Guide

Desired rate of drainage 6.

Roof drainage design guide.

Calculate the total roof area by multiplying its length by width. The greater the slope the less water build up and thus roof load. Size vertical storm drainage piping. The sizing of the roof drainage system must consider all components.

Calculate total roof area. First and foremost be sure to comply with all local plumbing codes. 2 3 4 5 6 and 8 in. Design assistance services are offered as a courtesy to the roofing design professional and contractors to ensure the project s success.

Secondary drainage shall be provided through the use of sidewall scuppers or internal roof drains. Volume of expected rainfall. Inspect the roof surface and roof drains on a regular schedule to find and clear away any debris clogging the drains. Location of drains 5.

Secondary or emergency roof drainage is required wherever the buildup of water is detrimental to the roof structure. Step by step instructions step 1. In the design and detailing of a roof drainage system consideration must be given to a range of factors such as. Size horizontal storm drainage piping.

The location and degree to which. Determine leader or pipe size. 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. 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.

Slope of the roof. 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. Properly designed roof drain must have the following features. Rainfall intensity roof catchment area gutter size capacity gutter fall gutter outlets sumps rain heads nozzles downpipe size quantity and placement overflow consideration material.

Safety load requirement 8. Select number of roof drains and calculate the roof area sloped to each drain. 2 3 4 5 6. Ipc provides four steps to size the roof drains on a building.

Type of roof construction 2. Structural design of the roof and roof load. Maximum pipe flow. From there consider the following.

When selecting a roof drain note. Roofs inevitably serve as temporary rainwater reservoirs. Determine 100 year 1 hour rainfall rate used for location of building. Inspect the current roof drain s and the drain line through the building for leaks and assure that the materials are.