Recently, Wright’s Arizona residential structural engineering team was approached by two builders, independently, to re-engineer plans that had been previously engineered by others. The builders had each used the plans for some time but hoped that Wright Engineers’ design would cut construction costs. When the bids came back, Wright’s value engineered design cut framing costs by over $800 per lot for one builder and over $2,000 per lot for the other builder. Considering that each plan may get built 50 or 100 times or more, the savings are significant!
FIVE LEVELS OF WOOD OVER PODIUM
It used to be unusual to see 5-story wood-framed buildings. Now it’s becoming the norm. Multi-family residential, mid-rise hotel, senior or assisted living, and similar projects are all reaping the benefits of 5-story wood construction. Commonly these projects are built on a concrete podium with parking or commercial and retail beneath. Because wood generally has lower material and installation costs, is relatively lightweight, and is fast to construct, it’s often an ideal solution.
Mid-rise wood construction has unique design challenges. Among them, fire detailing is critically important and can significantly affect the structural design. Floors should stack so that structural walls align at each level. Offsets may require steel framing which then must have special fireproofing detailing. Exterior wall framing must be fire-retardant treated lumber. The effects of wood shrinkage should be considered at elevators, stairs, and other vertically fixed elements. Buildings that wrap around garages need special building separation detailing and may need to consider potential differential settlement between the garage and the much lighter wood-framed structure. For courtyard wrap buildings, contractors need to consider interior access and coordinate with the design team to provide temporary access tunnels.
Wright Engineers is the structural engineer for numerous 5-story wood over podium or slab-on-grade projects currently in various stages of design, construction and completion in Nevada, California, and throughout the country.