The above sizing data is offered as a guide only.
How toselect a roof drain.
The new drain must fit flush on the roof surface inside the old drain bowl and the new outlet pipe must fit inside the old outlet pipe.
Sizing the drains for each system including the number of drains required is based on.
Calculate drains needed.
To select the proper roof drain the following information must be deter mined by the designer specifier.
The pitch of your roof also helps determine the type of materials that can be used on your roofing system.
In that case you would use one of our smaller bowl drains.
The old bowl may be a little or a lot too shallow for this.
The best type for the application depends on several factors such as the size and slope of the roof the desired appearance and how much regular maintenance the drain system might need.
It is an essential element to ensure water drains properly off of your roof.
Take the roof s total square footage and divide by the total square footage handled by one drain.
The roof structure may sag due to the added weight of ponding water.
This table is based on zurn s roof drain vertical requirement for horizontal roof areas at various rainfall rates table.
The clamp tite small bowl commercial drain and value drains are designed to meet this.
Roof drains for flat or low slope roofs come in a few standard types.
Determine 100 year 1 hour rainfall rate used for location of building select number of roof drains and calculate the roof area sloped to each drain size horizontal storm drainage piping size vertical storm drainage piping.
First and foremost be sure to comply with all local plumbing codes.
The result is the number of drains needed.
The zurn roof drains and drain accessories represent more than 100 years of experience in supplying engineered roof drainage equipment to the construction market.
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.
Roofing materials are designed specifically to be compatible with the pitch of the roof.
Floor drains or area drains when used to drain exterior areas should have an open area equal to twice the transverse area of the connecting pipe table 1 see roof drain section for rainfall and sizing data table 1 recommended grate free areas for various outlet pipe sizes.
The primary reason roof pitch exists in the first place is to redirect water.
To select the proper roof drain the following information must be known.
Type of roof construction roof pitch maximum volume of expected rainfall and storm design criteria this information must be obtained from your local weather bureau and or local code authority desired rate of drainage.
Ipc provides four steps to size the roof drains on a building.
