The unit for wind pressure is pounds per square foot psf.
Wind lbs on roof.
Depending on the location a typical wind load is 80 mph or 16 lb ft2.
Wind pressure is given by the equation p 0 00256 x v2 where v is the speed of the wind in miles per hour mph.
Because fm approvals requires a 2 1 safety factor roofs with field of roof uplift forces of 30 pounds per square foot are the maximum for 1 60 ratings and 37 5 pounds per square foot are the.
Wind flow over a roof pulls upward.
The upward movement of the wind exerts an uplift load on the roof and the roof must be able to resist this uplift.
Slipperiness of the roof.
When building a structure it is important to calculate wind load to ensure that the structure can withstand high winds especially if the building is located in an area known for inclement weather.
Less snow will accumulate on a slippery roof it will slide off instead.
Wind flow under a roof pushes upward.
Uplift load wind flow pressures that create a strong lifting effect much like the effect on airplane wings.
A typical uplift load limit assumes a maximum wind speed of about 90 miles per.
If your roof is located in windswept areas or even north of the treeline the wind will cause snow drifting making less of it accumulate on your roof.
As you might expect buildings of high importance such.
For example if the wind speed is 70 mph the wind pressure is 0 00256 x 70 2 12 5 psf.