Canopy sag or deflection occurs in cantilevered deck and between supporting columns. Sound engineered sag will meet the structural requirements of the I.B.C. (International Building Code).
Adding the weight of a perimeter gutter full of water to the Canopy causes additional sag or deflection which negatively effects the draining water flow. Proper Canopy design requires another step to assure the Canopy sag is small enough to allow proper drainage flow and, therefore, to meet the AISC ponding criteria so water will flow and not collect which could cause a Canopy failure.
Sag or deflection is measured in engineering terms. The IBC structural requirements may only require L/120 or L/150 criteria. The second step, which may be side-stepped by some, meeting the AISC's anti-ponding requirements, is achieved by using a tougher L/180 criteria and achieves the needed drainage flow. This makes a Canopy 18% stiffer or stronger.
Using this tougher criteria for 32+ years, Austin Mohawk has had zero structural Canopy failures, unlike a number of our competitors.