3. Draining the Roof

Question 1

ARMA?

Answer 1

Asphalt Roofing Manufacturer Association

Question 2

NRCA

Answer 2

National Roofing Contractors Association

Question 3

UBC

Answer 3

Uniform Building Code

Question 4

What is the minimum slope recommended by the UBC, ARMA, and other organizations?

Answer 4

1/4” (2 percent)

Question 5

What is the common reasoning for not adding more slope?

Answer 5

It is expensive and more difficult.

Nicer explanation would be to say the roof may become a floor in a potential expansion

Question 6

What happens to the Total Life-Cycle Roof Costs as you go past 1/4” (2 percent)

Answer 6

the total costs starts going up and the added benefit of maintenance does not outweigh the initial costs.

Question 7

What is interior drainage vs peripheral drainage? Which is considered more effective?

Answer 7

Interior drainage uses internal pipes that flow water through the building and out through an underground drainage system.

Peripheral is the opposite. The water goes from elevated internal areas to peripheral low points (scuppers)

Interior is better for colder climates

Question 8

What is a cricket? What is another name for it?

Answer 8

Crickets are the ridges designed to divert water, typically away from large penetrations like skylight. They are also called saddles.

Question 9

to ensure good drainage, specify a minimum of _______ drains for a total roof area less than 10,000ft2. Limit the maximum spacing of drains in any direction to ____LF

Answer 9

2
75

Question 10

What is a Siphon Drainage System?

Answer 10

set of pumps placed in ponded areas of a roof with plastic hoses leading to roof drains. The system starts when the water ponds to 5/8-inch

Question 11

Locate drains at ___________ (should be obvious, but often overlooked)

Answer 11

low points

Question 12

Provide _________ at drains below the adjacent roof level

Answer 12

sumps

Question 13

What is used to prevent clogging and debris in drains?

Answer 13

drain inlets