323 75TH ST SE BLDG C 2023-07-31

Introduction: Definitions of Exposure per IRC 2009 R301.2.1.1 Exposure Category: For each wind direction considered,an exposure category that adequately reflects the characteristics of ground surface irregularities shall be determined for the site,at which the building or structure is to be constructed.For a site located in the transition zone between categories, the category resulting in the largest wind forces shall apply.Account shall be taken of variations in ground surface roughness that arises from natural topography and vegetation as well as from constructed features.For a site where multiple detached one-and two-family dwellings,townhouses or other structures are to be constructed as part of a subdivision'master-planned community,or otherwise designated as a developed area by the authority having jurisdiction,the exposure category for an individual structure shall be based upon the site conditions that will exist at the time when all adjacent structures on the site have been constructed,provided their construction is expected to begin within one year of the start of construction for the structure for which the exposure category is determined.For any given wind direction,the exposure in which a specific building or other structure is sited shall be assessed as being one of the following categories: 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.Exposure B shall be assumed unless the site meets the definition of another type exposure. Exposure C:Open terrain with scattered obstructions,including surface undulations or other irregularities,having heights generally less than 30 feet(9144 mm)extending more than 1,500 feet (457m)from the building site in any quadrant.This exposure shall also apply to any building located within Exposure B type terrain where the building is directly adjacent to open areas of Exposure C type terrain in any quadrant for a distance of more than 600 feet(183 m).This category includes flat open country,grasslands and shorelines in hurricane prone regions. Exposure D:Flat,unobstructed areas exposed to wind flowing over open water(excluding shorelines in hurricane prone regions)for a distance of at least 1 mile(1.61 km).Shorelines in Exposure D include inland waterways, the Great Lakes,and coastal areas of California,Oregon,Washington and Alaska. This exposure shall apply only to those buildings and other structures exposed to the wind coming from over the water.Exposure D extends inland from the shoreline a distance of 1500 feet(457 m)or 10 times the height of the building or structure,whichever is greater Project James G. Pierson Job no. , Inc. Innovative Glass Railing System Consulting Structural Engineers Location Date 3/30/20 Washington and Oregon 610 S.W.Alder,Suite 918 Portland,Oregon 97205 Tel: (503) 226-1286 Fax: (503) 226-3130 Client • Sheet no. • Innovative Aluminum Systems, Inc. page 12 of 12