Positive Draininage On A Roof

Nrca has chosen the performance based approach to positive drainage and.

Positive draininage on a roof.

In previous years tapered systems were created on site by cutting and shaping regular roof insulation components. Today many manufacturers offer. Water adds significant weight to a building especially if the drains are clogged or poorly implemented. Positive drainage should allow the water to drain off the roof 24 48 hours after it stops raining.

Positive drainage is created when you create surface drainage by grading an area so that water collects and flows to a lower elevation away from buildings structures. Positive drainage conditions are created by routing water around deflections to lower points on the roof via tapered systems where the water can be evacuated. Architects must also take into account the weight of water on the roof including near the drainage areas. Well considered foundation design and its interface with surrounding soils combined with effective site drainage can eliminate most moisture problems that are typically found in basements.

Positive drainage noun 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 within 48 hours following rainfall during conditions conducive to drying. Positive drainage is part of any well planned roof design.