The Seattle Housing Authority engaged RDH to provide building enclosure consulting for a comprehensive exterior wall rehabilitation aimed at improving building envelope performance and extending the building’s service life. The original stucco and cedar siding were removed down to the wood stud framing and replaced with a high-performance rainscreen assembly. GGLO served as design architect.
The new wall system incorporates new plywood sheathing, a liquid-applied water-resistive air barrier, and a continuous 1¼” layer of high-density mineral wool insulation, finished with fiber cement siding. The assembly achieves a 1-hour fire rating from both the interior and exterior sides, as well as between floors.
Securing approval for the assembly required a creative code compliance path. RDH prepared and submitted a Code Modification Request demonstrating that the proposed assembly met the intent of the 2006 Seattle Building Code, specifically Sections 720 and 721.6 covering fire-resistance-rated wood assemblies, and Sections 104.9 and 104.10 governing alternate materials and methods. The approach increased fire safety while delivering long-term thermal and durability benefits.
Construction was led by Tatley Grund and sequenced to minimize disruption to residents throughout the rehabilitation.
