Clogged roof drains ponding water sagging roofs.
How toselect a roof drain.
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.
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.
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.
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.
When the through building roof drain system has become clogged even if it does not burst and lead to building flooding it causes other building problems.
Any clog in the internal drain or scuppers leads to ponding where water simply sits on your roof.
Calculate drains needed.
The water weight compresses roof insulation leading to more ponding.
In these conditions typical solutions to disposing of roof runoff include.
Take the roof s total square footage and divide by the total square footage handled by one drain.
Ipc provides four steps to size the roof drains on a building.
The result is the number of drains needed.
This table is based on zurn s roof drain vertical requirement for horizontal roof areas at various rainfall rates table.
To select the proper roof drain the following information must be deter mined by the designer specifier.
Sizing the drains for each system including the number of drains required is based on.
Drain by gravity to a nearby storm drainage system.
To select the proper roof drain the following information must be known.
The above sizing data is offered as a guide only.
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.
Pump roof runoff from a collecting basin or pit at the building to a remote seepage pit storm sewer or catch basin.
In that case you would use one of our smaller bowl drains.
The drains must allow a large volume of water equal to the square footage of your roof times the number of inches of rain to drain quickly.
Roof drains for flat or low slope roofs come in a few standard types.
When selecting a roof drain note.
The roof structure may sag due to the added weight of ponding water.
The zurn roof drains and drain accessories represent more than 100 years of experience in supplying engineered roof drainage equipment to the construction market.
First and foremost be sure to comply with all local plumbing codes.
