The code currently adopted by the state of Washington is the 1997 Uniform Building Code (UBC). You can buy the code from any of the code organizations on the left or through your local building regulations department.

For your convenience the the masonry chimney section of the developing International Residential Code (IRC) is available as a working document at http://www.rumford.com/code/IRC01.html While the language may be similar the IRC is not the official code.