Snow loads for Whatcom County are determined by the study produced by the Structural Engineers Association of Washington (SEAW) as revised in January of 1997. The snow loads that are given are ground snow loads and for the design of the structure may be reduced by calculation per the current adopted codes by a design professional.
A design professional shall take into account exposure, slope, snow drift, unbalanced snow, sliding snow, roof valleys, adjacent roofs, lower roofs, and all other load cases as required per the current code requirements.
Snow load is determined by multiplying the site elevation and the given isoline under which it falls as set by SEAW (click here to see the Snow Load Revision chart). This table shows general locations by elevation and the given snow load for those areas. For accurate snow load information for your site call Whatcom County Planning and Development Services at (360) 676-6907 with your parcel number and have a Plans Examiner look it up for you.