Is compliance with the performance requirements of the A440 amalgamated standard required for you folks?
This came into our code 5 years ago and was initially a headache to enforce, but has gotten a lot better. Unlike the US where are the performance requirements are bound to the performance grade, in Canada we look at the positive and negative design pressures, water penetration rate, and air infiltration( only required in Canada under the Canadian supplement) in isolation.
When we first started inspecting, many of the suppliers and even some of the manufacturers were sending windows that did not meet code into our market. Usually we were able to catch this at the time of ordering (we ask for the suppliers spec sheet as part of the permit process). So most of the time we catch it before the windows are even started at the factory. We continue to have some problems with a particular big box store that is associated with the colour orange.
The issues can either be window failure due to excess deflection where the proper negative or positive design pressures are not used, the window leaking water where the proper water penetration pressure is not met, and in Canada, drafty windows where the air infiltration rate is not met.
We have a local home warranty company that tells us that their average cost of repair for a single leaky window is $7,000.