Plumbing Storm Drainage

Question 1

Under the IPC, storm drainage systems are sized using which rainfall rate?

Accepted Answer

100-year, 1-hour rainfall

Answer

The IPC bases storm drainage sizing on the 100-year, 1-hour rainfall rate for the location, taken from the code's rainfall maps or local data.

Question 2

Under the IPC, roof drain strainers must extend at least how far above the roof surface around the drain?

Accepted Answer

4 inches

Answer

IPC 1105.2 requires roof drain strainers to extend at least 4 inches above the surrounding roof surface. Flat-deck strainers are allowed on decks used for other purposes.

Question 3

Secondary (emergency) roof drains or scuppers must discharge:

Accepted Answer

To an above-grade location where the discharge is readily observable

Answer

Secondary roof drainage must be a separate system from the primary drains. It discharges above grade where occupants can see it, which signals that the primary drains are blocked.

Question 4

When sizing roof drainage, how do the IPC sizing provisions account for rain running off a vertical wall onto the roof?

Accepted Answer

Add 50% of the wall area to the projected roof area

Answer

Wind-driven rain hits vertical walls and runs onto the roof below. The IPC adds 50 percent of the area of the adjacent vertical wall to the projected roof area when sizing the drains.

Question 5

Under the IPC, storm water is generally prohibited from discharging into:

Accepted Answer

A sanitary sewer intended for sewage only

Answer

The IPC prohibits draining storm water into sewers intended only for sewage. Storm water overloads sanitary systems and treatment plants.

Plumbing Practice Test

Plumbing Practice Test

Plumbing Storm Drainage