WIND DESIGN CALCULATOR

Project Name  
Building Height (feet) 
Exposure (B, C or D)     Help!
Importance Classification     Help!
Basic Wind Speed (MPH)    Help!
 

EXPOSURE

Exposure B
Urban and suburban areas, wooded areas, or other terrain with numerous closely spaced obstructions having the size of single-family dwellings or larger. Use of this exposure category shall be limited to those areas for which terrain representative of exposure B prevails in the upwind direction for a distance of at least 1,500 feet (460 m) or 10 times the height of the building or structure, whichever is greater.

Exposure C
Open Terrain with scattered obstructions having heights generally less than 30 feet (9.1 m). This category includes flat open country and grasslands.

Exposure D
Flat, unobstructed areas exposed to wind flowing over water for a distance of at least 1 mile (1.61 km). This exposure shall apply only to those building and other structures exposed to the wind coming from over the water. Exposure D extends inland from the shoreline a distance of 1,500 feet (460 m) or 10 times the height of the building or structure, whichever is greater.

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IMPORTANCE CLASSIFICATION

Category 1
Buildings and other structures that represent a low hazard to human life in the event of failure including, but not limited to:

* Agricultural facilities
* Certain temporary facilities
* Minor storage facilities

Category 2
All buildings and other structure except those listed in Categories 1, 3, and 4.

Category 3
Buildings and other structures that represent a substantial hazard to human life in the event of failure including, but not limited to:

* Buildings and other structures where more than 300 people congregate in one area
* Buildings and other structures with elementary school, secondary school, or day-care facilities with capacity greater than 250
* Buildings and other structures with a capacity than 500 for colleges or adult education facilities
* Healthcare facilities with a capacity of 50 or more resident patients but not having surgery or emergency treatment facilities
* Jails and detention facilities
* Power generating stations and other public utility facilities not included in category 4
* Buildings and other structures containing sufficient quantities of toxix or explosive substances to be dangerous to the public if released

Category 4
Buildings and other structures designated as essential facilities including, but not limited to:

* Hospitals and other healthcare facilities having surgery or emergency treatment facilities.
* Fire, rescue and police stations and emergency vehicle garages
* Designated earthquake, hurricane, or other emergency shelters
* Communications centers and other facilities required for emergency response
* Power generating stations and other public utility facilities required in an emergency
* Buildings and other structures having critical national defense functions

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