Interpretation #8630

Original Request

Code Version: 2021
Code: EXTBLDG
Code Description
Chapter
Section: 706
Topic: Secondary Roof Drainage

Question

Given a structure is undergoing a level 3 alteration, an addition, and replacement of roof insulation and roof covering, is secondary drainage required to be installed if it is not present at the existing building currently?

Answer Published 03/15/2022 at 9:01 AM

FBC-EB 706.1 states that when recovering or replacing an existing roofing covering they shall comply with the requirements of Chapter 15 FBC Building. FBC Building 1503.4 states that "Where roof drains are required, secondary (emergency overflow) roof drains or scuppers shall be provided where the roof perimeter construction extends above the roof in such a manner that water will be entrapped if the primary drains allow buildup for any reason." If the drains would have been required for new construction, they are required during reroof, whether existing or not.

Commentary

This requirement is intended to prevent excess water accumulation and the weight it creates from accumulating on the roof and causing a failure of the roof system. That failure could be a leak from the pressure of the water or a potential collapse of the roof structure. Based on protecting the occupant and the structure, secondary roof drains are required.