Maddux

Maddux is a two-building, multifamily, affordable housing project in Seattle’s Mt. Baker neighborhood, near the Mount Baker light rail station. Maddux North is 101 units and nearly 110,000 SF. Maddux South has 102 efficiency units and approximately 58,000 SF. South McClellan Street, a busy arterial, runs between the north and south buildings. The six and seven-story buildings also include parking, offices, and approximately 3,500 square feet of commercial space. Soil remediation work was extensive and complex. Maddux North was the former site of a dry-cleaning business, and Maddux South had been the site of a gas station.

In addition to complications stemming from the DOE-funded clean-up of contaminated and “dangerous” soils (the classification for the most highly contaminated soils), the project was also located on liquefiable soils. W.G. Clark worked directly with the city to engineer and then installed a first-to-market “rigid inclusion” soil improvement solution. These sites also included a high water table, requiring a contamination-resistant waterproofing membrane on the shoring and under the building slabs. Both buildings sit on sloped sites with complicated on-grade stepped slabs that required waterproofing. W.G. Clark created a series of details for approval by the waterproofing manufacturer that made it possible for these projects to be water-tight.

During preconstruction, W.G. Clark suggested changing to six stories of wood framing at Maddux South to help solve some budget challenges. The project became one of the first six-story wood buildings to be permitted and built in Seattle. With unique challenges stemming from contaminated and unsuitable soils, sloping sites, an arterial through the middle of the project, bond financing, and construction during early-COVID, Maddux was still completed with nearly no use of owner contingency funds except for added scope.