The new Chicago Botanic Garden Plant Science Center will provide laboratories and teaching facilities for more than 200 Ph.D. scientists, land managers, and students. The 38,000-sq ft Center also serves as home to a unique doctoral program in plant biology and conservation with Northwestern University, and as headquarters for the Garden's international efforts in plant conservation. A viewing gallery and the 16,000-sq ft Green Roof Garden are open to the public, giving nearly 800,000 visitors each year the opportunity to view plant science firsthand. As part of the effort to achieve a LEED gold rating, the 5,000-sq ft main visitors gallery was designed to be a thin, radiant-heated slab of colored and polished concrete without synthetic floor coverings.
Client concerns included:
- Visual appearance of the visitors gallery finished floor was critical, including maximizing flatness and uniformity of color while minimizing the potential for random cracks
- Behind the scenes, thin overlay radiant heated laboratory floors also required non-standard preparation for resilient floor coverings
- Floor details for the balcony and conference room area on the second floor were redesigned to improve the long-term appearance and avoid random cracking showing through finish flooring
CTLGroup worked with the architect to review and revise concrete mix designs and to develop construction details to avoid unwanted random cracks in the thin overlay radiant heated concrete. Placement patterns for radiant heating tubes, construction joints, sawcut shrinkage control joints, and insulated subbase details were critically evaluated and finalized. We also developed procedures for the placement, finishing and curing to maximize the uniform appearance of the floor finish over this large area. In laboratory areas, we developed repair plans for areas of the floor the required corrective action before installation of resilient floor coverings.
Floors in laboratory areas were successfully repaired and covered with resilient flooring which has a uniform appearance and no reflection of the excessive cracks that occurred during construction. The main visitors gallery is a showplace of colored and polished concrete that should wear exceptionally well with high volumes of foot traffic expected annually. Construction and finishing went smoothly and no unwanted cracks developed in the entire main gallery area.