Near where I live is Dulles International Airport, 50 km west of Washington DC. A relatively new hanger there collapsed recently due to snow load on the roof. With the metric system you can do the extra load calculation in your head. Hopefully I got the math correct.
Dulles airport had 53 cm of snow. Fluffy snow is about 10% water, so about 53 mm of rain equivalent equals about 53 L/m2 or 53 kg/m2 (lets call it 50 kg/m2 for simplicity) If the hanger is 100 x 50 m equals 5000 m2 times 50 kg/m2 equals 250 000 kg or 250 additional tons on the roof of the building. I wonder what units the architect used? They've had this much snow before so why didn't it withstand the load? Michael Payne
