At 135,000 square feet, the TWA Corporate Headquarters Building in Kansas City, Mo., is the largest project that El Dorado has completed to date, and the only one already listed on the National Register of Historic Places. Originally constructed in 1956, the cast-concrete and metal façade subsequently had been covered by a layer of mud-brown stucco. El Dorado restored the white-and-red exterior color scheme (using the original concrete panels and replacing the red metal panels with back-painted glass) and enclosed an alleyway that bisected the building.
The project’s most arresting new feature is an expansive green roof that manages stormwater runoff. The team chose a system by American Hydrotech that has continuous waterproofing running underneath planted and nonplanted tiles (made from ipe planks). This allows the vegetated area to be complemented by pathways and patios that the building tenants can use for events and meetings. The vegetated sections have three inches of soil planted with tall grasses and native plants. “We wanted to explore the idea of bringing the prairie to the top of the building,” principal David Dowell says.
The interior—now an advertising agency—was fitted out by another firm, but El Dorado designed an underfloor system for airflow and data distribution, installed energy-efficient elevators, and designed the stairwells and bathrooms. The entire project was completed for $72 per square foot and came in $500,000 under budget. The cost of the green roof was offset by using effective but very inexpensive corrugated plastic to cover the rooftop HVAC units. Dowell notes that the material’s most common application is on the kitchen vents on Wendy’s franchises, and jokingly worries about a price hike if higher-end use of the product takes off.
The roof is also graced with a new version of the original building’s iconic Moonliner II rocket—modeled after the 80-foot-tall version at Disneyland. But that is not the only art integrated into the project: In an adjacent alley that connects the building and the neighboring parking garage is an installation of moving metal pieces by artist James Woodfill. This space also features benches, stair rails, and movable gates fabricated by El Dorado.
The TWA building is more than just another project in the El Dorado portfolio; it marks a new direction for the firm and represents the type of bigger, higher-profile projects that it hopes to do more of in the future.