Hilltop Heritage Elementary School (ES No. 16)

Creative mass timber systems steal the show at this new elementary school for the Renton School District. Respecting the budget and building complexities, the team carefully selected locations for exposed mass timber. Acoustic DLT supported by glulam beams was chosen for large, busy spaces like the gym, commons, and library. Classroom wings feature CLT floors and roofs plus post and beam construction, achieving the warm, wood tones desired by the design team. And finally, the team used the spanning capability of the CLT panels to economize the post and beam framing, minimizing the piece count and maintaining an efficient CLT panel thickness that fit within the geometry.

Creative design resulted in a thin deck, reduced spans, and resourceful use of cantilevered CLT panels. Rotating the beam framing and cantilevering the panel end resulted in economized CLT panels with reduced back spans – a different column and beam layout. Instead of manufacturing a custom panel, costs were kept low by selecting a universal panel size (5-ply stock) and working within its confines. Ultimately, the team economized the panel without increasing the number of beams and columns on the job.

The custom carbon study presented to school district decision makers included the building’s total carbon storage, numbers translated to automobiles, and ideas for how to use the structure as a tool and teaching vessel.