Question

What is the minimum diameter and extension above the roof line of a vent pipe to

prevent frost/snow closure?
a. 4-inch diameter and 12 inch extension
b. 3-inch diameter and 10-inch extension
c. 3-inch diameter and 6-inch above snow line
d. 2 ½-inch diameter and 8-inch extension

Answer 1

The common practice to prevent vent pipe closure by frost or snow is to use a 4-inch diameter pipe that extends at least 12 inches above the roof line, although local building codes vary.

Step-by-step explanation:

The minimum diameter and extension above the roof line of a vent pipe to prevent frost/snow closure is typically determined by local building codes, which may vary based on the climate and average snowfall of a region. However, a common practice is to use a 4-inch diameter vent pipe that extends at least 12 inches above the roof line. This sizing helps to prevent the vent from being blocked by frost or snow accumulation. While other sizes such as a 3-inch diameter with 6 or 10 inches of extension may also be permissible in some areas, the 4-inch by 12-inch specification is commonly recommended to ensure adequate airflow and prevent potential blockages from weather conditions.