RRC Roof Drainage & Slope Design 2

Question 1

What is a 'cricket' or 'saddle' used for in roof design?

Accepted Answer

A peaked diverter built on the high side of a penetration to redirect water around it

Answer

A cricket (or saddle) is a peaked construction built on the upslope side of a chimney, skylight, or other large penetration to divert water around the obstruction and prevent ponding behind it.

Question 2

At what height above the roof surface is the inlet of an overflow drain typically set?

Accepted Answer

2 inches above the roof surface

Answer

Overflow drain inlets are set 2 inches above the roof surface so they only activate when primary drains are overwhelmed and water depth exceeds this threshold.

Question 3

What is the primary design purpose of a tapered insulation system on a low-slope roof?

Accepted Answer

To create positive drainage slope on a structurally flat deck

Answer

Tapered insulation systems vary in thickness across the roof to create positive drainage slope toward drains on decks that are structurally flat or have insufficient built-in slope.

Question 4

The design rainfall intensity used for roof drainage calculations is typically derived from which data source?

Accepted Answer

NOAA precipitation frequency data (Atlas 14)

Answer

Roof drainage calculations use NOAA's precipitation frequency data (Atlas 14) to determine design rainfall intensity for the specific geographic location of the project.

Question 5

What is the standard formula for calculating required roof drain flow rate (Q in GPM)?

Accepted Answer

Q = A × I / 96.23 (A=sq ft, I=in/hr)

Answer

The formula Q = A × I / 96.23 converts roof area (sq ft) and rainfall intensity (in/hr) into required flow rate in gallons per minute for drain sizing.

RRC - Registered Roof Consultant Practice Test

RRC - Registered Roof Consultant Practice Test

RRC Roof Drainage & Slope Design 2