The wind flow resistance is determined by dividing the sustained wind speed, which is defined as the incremented speed level before failure occurs, by a minimum safety factor of 1.5, as per CSA A123.24-15. Since the airflow machine can deliver a wind speed of 200 km/h (124 mph) at maximum capacity (current at time of publication), this limits the maximum sustained wind speed of any VS tested to 200 km/h, which corresponds to a maximum wind flow resistance of 133 km/h (82 mph) after applying the 1.5 safety factor. This can become an issue for projects with design wind speed greater than 133 km/h. Wind engineers will need to review the specifics and offer professional opinions for these projects.

The designers should note CSA A123.24-15 is not applicable to a mechanical attached roofing system, but appropriate for adhesive adhered roofing system and a partially adhered roofing system. Currently, CSA A123.24-15 is applicable to a modular vegetated roofing system only and not built-in-place systems, where young vegetation are planted in growing substrate on the roof. However, the CSA A123 technical committee is in the process of revising the standard to include built-in-place VRA in the next revision of the standard based on new research findings coming out of National Research Council Canada (NRC).