Metal Architecture Home

Working with the Flow

Riverwalk  Pavilion

Grand Award for the 2015 MA Design Awards

The intersection of Court Avenue and Water Street in downtown Des Moines, Iowa, serves as a nexus of competing and complementary interests and demands. On that spot, the Court Avenue Bridge crosses the Des Moines River, and it is a gathering magnet for people streaming from the restaurants and night life of Court Ave. The Principal Riverwalk cuts through there. It is a multiuse path along the river sponsored by Des Moines-based Principal Financial Group. On-site also is a pump station that during times of flood, such as the devastating 2008 floods, keeps the rising waters from reversing the stormwater system flow back into the buildings of downtown Des Moines.

The riverwalk master planners, Philadelphia- based Wallace Roberts & Todd, had long envisioned a café on that spot that would provide refreshments and public restrooms. Des Moines-based Substance Architecture stepped forward with a plan that created a dynamic pavilion and established a gathering plaza, while architecturally connecting the café to the pump station across the street. The connection is made by the triangular shape of the buildings and the use of metal panels, which were VMZ Standing Seam Panels from Umicore Building Products USA Inc., Raleigh, N.C.

The play with the triangular building forms, metal panels and glass creates a conversation between buildings, tying them together. Substance Architecture principal Paul Mankins, FAIA, LEED AP, says, "The pump station is what the café looked like before it unfolded."

It is that sophisticated simplicity that captured the attention of the Design Award judges, who extolled the inventiveness of the spaces being created and how the disparate parts can create a cohesive whole.


Site and Shape

"Initially," says Mankins, "this site was to be two flat plazas that allowed people to go out to look at the river. There was no actual program on either of these sites as part of the master plan. Relatively early they decided they need an amenity to draw people to the riverwalk."

Not only did the original conception change, but the nature of the building changed as well. "It had always been conceived as a one-story, linear building placed on the west side of this boat-shaped plaza," explains Mankins. "After we'd been selected, we convinced them that the building should be at the prow of the boat shape. And moving it far enough would allow it to become a two-story building. That modification reduced the visual mass of the building in half."

The first floor of the building now sits below the top of the limestone flood wall and houses the public restrooms and electrical equipment necessary to feed the riverwalk lighting. Above the flood wall, the positioning opened space for more an open-air plaza next to the building. People now walk across the plaza to the building, offering a clear view of the river, rather than having to enter the building to get to the plaza to see the river.

Joshua Baker, AIA, LEED AP, was the project architect for Substance Architecture. Placing the building at the prow forced it to become a triangular shape, he says. "Triangular buildings don't help on budget concerns because it's hard to come up with a system that is repetitive. But one of the things I really like with the pavilion and how the skin was dealt with is that the building changes when you walk around it. It's really open and focused toward the river so the glass is all toward the river side. And the roof and west wall is kind of a backdrop, getting the building out of the way. If you're on the Court Avenue Bridge, the view up the river or back toward the city is completely different than as you walk around on any other side. "

As Mankins describes, the building appears to fold up and out toward the river, with the metal paneling serving as the hinge point.



The metal panel roof drops down along the west elevation and forms into a series of louvers that shade the interior from the sun, but still allow light through. The panels then form another right angle, jutting out to establish a protective canopy for the entrances to the public restrooms on the first floor. The louvers, the right-angle bends and the standing seam panels themselves all emphasize the foldability of the metal, giving lightness to the building.

Further emphasizing the lightness of the glass and metal is the triangular balcony that interrupts the west elevation. The platform forms part of the sequence for the accessibility entrance to the building, but it does more. "We thought it was important to have a place to break that skin," says Baker. "All the views back to the city are sort of obstructed. You can see through the screen because the louvers line up and you get a view back. But we thought you should be able to look back, or look up and down the river."


The Pump Station

The pavilion and the plaza get the most attention because they attract people. On the other side of Court Ave., though, the pump station is pure mechanical. "We hope it never has to work," says Mankins, but also recognizing that Des Moines has suffered two 500-year floods in the last 20 years.

"The pump station is made up of layers," Mankins says. "The inner layers are glass and the outer layer is wrapped in zinc. The other building reveals the core." That other building is little more than a fence that wraps around the gate valve. Neither the pump station nor the gate valve structures have roofs.

Both, though, repeat the triangular language of the pavilion and use the same materials in variation. The idea, according to Mankins, "It's a fence and want to show the light inside. There is a dark presence on one side of the trail and light on the other side."

What impressed the judges was how the zinc paneling is essential to the success of the project. Baker says: "We did explore quite a few options early on. One of the main things we were interested in was using one high-performing material that will last for a long time and have a natural aspect to it. We wanted it to age over time."


Principal Riverwalk Pavilion and Pump Station, Des Moines, Iowa

Completed: January 2013
Total square footage: Pavilion: 2,200 square feet. Pump Station: 3,485 square feet.
Building owner: Pavilion: City of Des Moines. Pump Station: Rock Island District Corp of Engineers
Architect: Substance Architecture, Des Moines,
General contractor, Pavilion: Covenant Construction Services, Waukee, Iowa,
General contractor, Pump Station: Larson and Larson Construction, Urbandale, Iowa,
Metal panel installer, Pavilion: Midwest Glazing, Chicago,
Metal panel fabricator, Pump Station: Architectural Wall Systems Co., West Des Moines, Iowa,
Metal panel installer, Pump Station: Exterior Sheet Metal, Grimes, Iowa,
Metal wall panels: Umicore Building Products USA Inc., Raleigh, N.C.,

Photos: Gilbertson Photography