Building Loading - Wind Exposure (1991 UBC, 1994 UBC, 1997 UBC)
Exposure B: Refers to terrain, which has buildings, forest or surface irregularities 20 feet or more in height covering at least 20 percent of the area extending one mile from the site.
Exposure C: Refers to terrain, which is flat and generally open, extending one-half mile or more from the site in any full quadrant.
Exposure D: Represents the most severe exposure in areas with basic wind speeds of 80 miles per hour (mph) or greater and has terrain which is flat and unobstructed facing large bodies of water over one mile or more in width relative to any quadrant of the building site. Exposure D extends inland from the shoreline 1/4 mile or 10 times the building height, whichever is greater.