From the North or South on I-5, take the NE 175th Street Exit (Exit 176). Go East at the Stoplight (NE 175th St). Head East past 12th Ave. NE, until you come to the North City Lumber sign. Turn Right, immediately before the North City Lumber sign, and continue through the alley past the lumberyard. pH Sciences will be on your left, behind the lumberyard.
From the Eastside, cross either the I-90 or I-520 bridge and head North on I-5 to the NE 175th Street Exit (Exit 176) and follow the same directions described above.