How Toselect A Roof Drain

The water weight compresses roof insulation leading to more ponding.

How toselect a roof drain.

Take the roof s total square footage and divide by the total square footage handled by one drain. In that case you would use one of our smaller bowl drains. The zurn roof drains and drain accessories represent more than 100 years of experience in supplying engineered roof drainage equipment to the construction market. 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 old bowl may be a little or a lot too shallow for this. The above sizing data is offered as a guide only. Roof drains for flat or low slope roofs come in a few standard types. In these conditions typical solutions to disposing of roof runoff include.

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. The clamp tite small bowl commercial drain and value drains are designed to meet this. This table is based on zurn s roof drain vertical requirement for horizontal roof areas at various rainfall rates table.

Any clog in the internal drain or scuppers leads to ponding where water simply sits on your roof. When selecting a roof drain note. Clogged roof drains ponding water sagging roofs. To select the proper roof drain the following information must be known.

Ipc provides four steps to size the roof drains on a building. 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 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. To select the proper roof drain the following information must be deter mined by the designer specifier.

Drain by gravity to a nearby storm drainage system. Pump roof runoff from a collecting basin or pit at the building to a remote seepage pit storm sewer or catch basin. Drain by gravity to a seepage pit or catch basin located on the property see french drain below. Calculate drains needed.

Sizing the drains for each system including the number of drains required is based on. 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. The result is the number of drains needed.