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RCW 64.55

    Why is RCW 64.55 important?

    This law was enacted as a result of rising insurance premiums and construction defect claims caused by water intrusion problems.  The goal was to ensure builders adequately planned for, and implemented effective waterproofing systems to protect the integrity of the building envelope.


    Requirements of the law include:

    • Preparation of plans, details and specifications for the building’s cladding system stamped by a licensed architect or engineer
    • A building permit issued through the local municipality or agency
    • Third-party independent inspection of the building enclosure throughout the project to ensure construction is compliant with the design documents
    • Water penetration testing on a representative sample of windows, doors and other utility penetrations to determine they meet acceptable standards for the prevention of water infiltration
    • Certificate of Occupancy Letter from the independent inspector declaring the building enclosure was inspected during the course of construction, and that work was done in compliance with project plans and specifications

    When does RCW 64.55 apply?

    The law applies to new construction projects where a building permit was issued on or after August 1st 2005.  This requirement applies specifically to residential buildings with more than two attached dwellings.  Most condominium communities fall under this category but there is an exception for properties where each building is located on a single lot, such as a zero lot line development.


    The consequences for failing to comply with RCW 64.55 are severe, and include difficulties in the sale of properties which do not comply with the law.