Wind Lbs On Roof

Wind flow over a roof pulls upward.

Wind lbs on roof.

Let s assume that the calculations for our building require a roof that can withstand 23 pounds per square foot of uplift force in the field of the roof. 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. For example if the wind speed is 70 mph the wind pressure is 0 00256 x 70 2 12 5 psf. Wind flow under a roof pushes upward.

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 exerts three types of forces on a structure. 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.

Uplift load wind flow pressures that create a strong lifting effect much like the effect on airplane wings. The unit for wind pressure is pounds per square foot psf. Less snow will accumulate on a slippery roof it will slide off instead. A typical uplift load limit assumes a maximum wind speed of about 90 miles per.

As you might expect buildings of high importance such. The upward movement of the wind exerts an uplift load on the roof and the roof must be able to resist this uplift.