Positive Draininage On A Roof

Tapered systems can be part of the roof s insulation system and are key components of both bur and single membrane systems.

Positive draininage on a roof.

Nrca has chosen the performance based approach to positive drainage and. 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. The term positive drainage is defined as the drainage condition in which consideration has been made for all loading deflections of the roof deck and additional roof slope has been provided to ensure drainage of the roof area within 48 hours of rainfall. Nrca defines positive drainage as the drainage condition in which considera tion has been made during design for all loading deflections of a deck and additional roof slope has been pro vided to ensure drainage of a roof area within 48 hours following rainfall under conditions conducive to drying.

Positive drainage is part of any well planned roof design. 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 should allow the water to drain off the roof 24 48 hours after it stops raining. Architects must also take into account the weight of water on the roof including near the drainage areas.

In previous years tapered systems were created on site by cutting and shaping regular roof insulation components. 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.