When selecting a roof drain note.
How toselect a roof drain.
Calculate drains needed.
The roof structure may sag due to the added weight of ponding water.
The old bowl may be a little or a lot too shallow for this.
Clogged roof drains ponding water sagging roofs.
Roofing materials are designed specifically to be compatible with the pitch of the roof.
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.
To select the proper roof drain the following information must be deter mined by the designer specifier.
The primary reason roof pitch exists in the first place is to redirect water.
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 zurn roof drains and drain accessories represent more than 100 years of experience in supplying engineered roof drainage equipment to the construction market.
It is an essential element to ensure water drains properly off of your roof.
To select the proper roof drain the following information must be known.
In that case you would use one of our smaller bowl drains.
This table is based on zurn s roof drain vertical requirement for horizontal roof areas at various rainfall rates table.
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.
The clamp tite small bowl commercial drain and value drains are designed to meet this.
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.
Ipc provides four steps to size the roof drains on a building.
The above sizing data is offered as a guide only.
The result is the number of drains needed.
First and foremost be sure to comply with all local plumbing codes.
Take the roof s total square footage and divide by the total square footage handled by one drain.
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.
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.
