Definition of Positive Roof Drainage

Standing water can create a host of issues on roof systems, but did you know that the definition of Positive Roof Drainage in the Florida Building Code (Chapter 15, Section 1502) includes a time qualifier of “within 48 hours of precipitation”?  Simply stated, this means to allow 48 hours after rainfall to measure or observe “standing water.”  With that being said, the 48-hour period could be the difference between acceptable positive drainage and what may appear to be a drainage issue.

See the full definition of Positive Roof Drainage from the Florida Building Code (Chapter 15, Section 1502) below:

POSITIVE ROOF DRAINAGE. The drainage condition in which consideration has been made for all loading deflections of the roof deck, and additional slope has been provided to ensure drainage of the roof within 48 hours of precipitation.

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