Positive Drainage On A Roof

The most established way to ensure constant water evacuation on a low slope roof is via positive drainage.

Positive drainage on a roof.

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. Exception 1 of section 1511 1 states existing roofs do not have to meet the requirements of the code if positive drainage is provided. I am building a new home soon and i do not want water drainage problems of any sort in my yard. Positive drainage prevents ponding.

Unless roofs are sloped to drain over roof edges roof drains shall be installed at each low point of the roof. 1514 4 all roof systems must be installed to ensure positive drainage. Meaning of positive drainage. Condition in which consideration has been made during design for all loading deflections of the deck and additional roof slope has been provided to ensure drainage within 48 hours following rainfall during conditions conducive to drying.

The minimum slope the code allows is in 12 in. My existing home is built on a slab and i frequently have standing water around the house after a rainfall. Positive drainage the drainage condition in which consideration has been made during design for all loading deflections of the deck and additional roof slope has been provided to ensure drainage of the roof area within 48 hours of rain during conditions conducive to drying. Positive drainage keeps a house dry.

The rationale for not requiring secondary drainage is that if positive drainage is provided that is adequate to drain the roof. 1515 2 2 1 in new construction the minimum deck slope shall be.