Positive Draininage On A Roof

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 draininage on a roof.

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. Water adds significant weight to a building especially if the drains are clogged or poorly implemented. 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. Positive drainage is part of any well planned roof design.

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. 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. Tapered systems can be part of the roof s insulation system and are key components of both bur and single membrane systems. Positive drainage should allow the water to drain off the roof 24 48 hours after it stops raining.

Today many manufacturers offer. Nrca has chosen the performance based approach to positive drainage and.