Note that a roof slope of 30°, ui = 1.2 on the leeward half of the roof which would increase the loading to 0.72 kN/m2.

Similarly substantial drifts can accumulate in valleys, behind parapets, and against neighbouring higher buildings, and these can lead to significantly higher snow loads for particular areas.

This would affect the permissible span for the cladding, and normally the purlin spacing would have to be reduced to support the additional load.