The Seattle Housing Authority engaged RDH to provide building enclosure consulting for a comprehensive exterior wall rehabilitation at an occupied residential building, with the goal of improving envelope performance and extending service life. GGLO served as design architect, with construction led by Tatley Grund and sequenced throughout to minimize disruption to residents.
The original stucco and cedar siding were removed down to the wood stud framing and replaced with a high-performance rainscreen assembly. The new wall system incorporates 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 new assembly required a creative approach to code compliance. RDH prepared and submitted a Code Modification Request demonstrating that the proposed assembly met the intent of the 2006 Seattle Building Code, addressing sections covering fire-resistance-rated wood assemblies and alternate materials and methods. The approved path increased fire safety while delivering meaningful long-term gains in thermal performance and durability.
