The AAMA gives windows a performance class and a performace grade. The performace class specifies minima for design pressure and water resistance test presure. These classes are residential, light commercial, commercial, etc.
But here is a strange twist. The minimum design pressure is 15 for residential and 30 for commercial. The AAMA label has the class (R, LC, C, etc.) followed by the grade (13,20,30, etc.). Now I have seen windows classified as R30 and C30. That implies the design pressure is the same. Does that imply that the R30 is able to meet the 30 design pressure but is able only to meet the water pressure minimum for residential windows, whereas the C30 window meets both water and design pressures of the commercial class?
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