The 30-story, 260 unit, 4Marq occupies the last parcel available on a busy downtown block that houses two other recently built structures, anchored between two busy downtown streets: Marquette and Fourth Street.
The close proximity to the other buildings required careful planning to ensure construction would fit on a relatively tight 15,800-square-foot site, said UrbanWorks project designer David Miller. “That was a block that was instant redevelopment,” he said. “Most of the challenges were construction logistics, such as figuring out deliveries, staging the tower crane and the hoists.”
The building reused the foundation walls remaining from the parking lot that once covered the site. 4 Marq’s parking garage was placed on the seven floors above the lobby and is hidden by perforated panels. The tinted two-layer anodized panels allow air to flow in from three sides, a money-saving approach that avoids the need for expensive mechanical ventilation. Units start on the ninth floor, with half of the apartments on that level featuring the only balconies available in the tower.
The $72.9 million project used precast construction to save time. Wells Concrete placed 476 pieces of wall panels with an acid etch finish. The horizontal stacked panels had punched openings and were supported on the CIP floor.
That show-stopping top floor “is a differentiator on this project,” Miller said. The billiards and club rooms have floor-to-ceiling windows from NanaWall that open and close. “It’s an amazing effect,” he noted. “When you can open this entire wall you have a shared amenity of indoor space and an outdoor roof deck with the skyline as your backdrop.”
This high-rise aligns with the Minneapolis Downtown Council’s 2025 Plan. Expanding the residential population of downtown to 70,000 has to start block by block; and this project goes a long way toward developing a neighborhood around this plan.
“Precast concrete was selected early for its ease and speed of construction. It was important to the design team that the panels visually expressed their exoskeleton nature of cladding the building. We collaborated with the fabricator and their engineers early in the process to push the envelope by minimizing the horizontal and vertical sections of concrete, maximizing window area, and beveling the openings and joints to create a seamless and uniform aesthetic. The result is an elegant composition of precast that fit the budget, stayed on schedule, and achieved our design goals in an efficient and unique way.”
– David Miller, AIA, LEED AP, Design Principal, UrbanWorks Architecture
“To maintain the aggressive 17-month schedule, the team reviewed and analyzed different cladding systems. After the options were analyzed and priced during predesign, the team decided to utilize a precast system. That information determined the material choices for schematic design and drove the development of the precast wall panels. The precast panels went through many design iterations to maximize the opening sizes, minimize the weight, and optimize the thickness to achieve a rich depth in the facade. To help drive the decision-making process, two mockup panels were produced and tested. One was a full-length panel, long-term tested at the precast yard over the winter for durability. The second was a complete panel with windows and insulation, built for constructability review.”
–Kelly Mansell, Construction Executive, Mortenson
Key Design Challenges
The panels had to be large in scale for economy, however the large punched window openings left little room for reinforcing 14” of concrete top and bottom and 22” wide vertical legs by 8” thick with beveled punch openings. The panel also had to meet a weight limit for the tower crane.
The installation was over two major downtown roads dealing with busy city streets and erecting at night.
This project was unique in that the general contractor was intending on proceeding with the finishing work at the lower levels while the building was being erected. This meant that they had to have a water tight envelope to protect the interior construction from water damage even though the building would still be under construction above where they would be working inside. Certain points of the construction process MAM would have to establish a floor level as a roof, and the building envelope below that point as a watertight barrier.
As this relates to the precast building envelope, the challenge was to establish the panel to panel joints as water tight, even though accessing the building’s exterior at that point in the construction process was out of the question for logistical and safety reasons.
This leaves the inside face of the precast to precast joints as the point where this could be accomplished. On this particular project, the horizontal precast to precast joints lined up exactly at the concrete floor levels, and were essentially hidden from view and untouchable from inside. The inaccessibility of the horizontal joints made the decision to try a “peel and stick” product to seal necessary.
The technique used was to slide a 12″ section of “peel and stick” down the narrow void between the inside face of the precast walls and the CIP slab edge, and after positioning, to apply pressure on the product to adhere it to the inside face of the precast to effectively seal the horizontal joints. This was also done to the inside vertical joints for continuity. Once precast envelope was completed, caulking of the precast joints proceeded from the outside of the building to complete the installation.
With the very thin panel section, the Precaster had little room for prestressing strand. Using a combination of lightly prestressed and very intricate bent mesh and rebar, they were able to manufacture the panels in a large size without cracking.
As mentioned earlier, this project was unique in that the general contractor was intending on proceeding with the finishing work at the lower levels while the building was being erected. This meant that they had to have a water tight envelope to protect the interior construction from water damage even though the building would still be under construction above where they would be working inside. Certain points of the construction process MAM would have to establish a floor level as a roof, and the building envelope below that point as a watertight barrier.
“A precast enclosure system allowed us the ability to get the building enclosed much quicker than a conventional multi-layer stick built enclosure system would have. This is critical in high rise construction where the floors are very repetitive and the driver to finishing the project is getting the building enclosed as quickly as possible. We were able to set an entire level of precast in five days, this meant that every five days there was another floor that we could start interior construction on.” –Kelly Mansell, Construction Executive, Mortenson