Think of the fenced-in area near the far south stairway on BAC as a lab. This is the location of the concrete mock-up that stirred so much speculation among faculty and staff earlier this spring. Hard as we tried to connect it to the McCord Hall design, we just never could make sense of it. For good reason: it’s just a model. The construction industry calls this kind of model a mock-up, and its purpose is to test ideas and materials. I read recently that mock ups give lie to the adage that there’s never enough time to do things right, but always time to do things over. The mock up is a chance to uncover potentially costly glitches, in advance, small scale.
Another large mock-up has sprouted a few feet away from the concrete. Where the concrete mock-up was all about the structure, or skeleton, of the building, this one was erected to test elements of the skin: waterproofing, flashing, windows and brick.
The walls of our new building are made of steel framing covered by an exterior sheathing material called Densglass. Mike Nixon, the W. P. Carey School’s representative on the site, said that the Densglass is like the standard sheetrock that is used to build walls, except that it has a water-resistant fiberglass surface/skin that provides a good substrate for whatever waterproofing is used. The gray coating that Mike and DPR’s Lew Laws are examining in the photo is a waterproofing sealant applied that is sprayed onto the Densglass.
The second picture shows the other side of the mock up – the side that’s easy to see from the BAC stairs. You can see the steel framing – the exact framing that will be used in the building. Everything on the mock up is built exactly to McCord Hall’s specs – a small scale sample of the building.
Last Friday the back of the mock-up where Mike is standing was covered with a sheet of clear plastic and sealed. Using two vacuums they created negative pressure inside the wall to test the efficacy of the sealant. Laws said it worked well.
Next, workers will lay bricks on the outside of the mock-up, installing the flashing that will allow water to drain and not collect inside the wall. Mike explained that the purpose of the bricks is to serve as a rain screen. They are not mortared to the sheathing (as I always thought!) but form a wall on their own that is anchored to the frame with brick ties. This makes the building flexible as it settles, Mike said, or during an earthquake. The mock up also tests the sheet metal flashing that directs water to drainage openings in the brick.
The window opening you can look through over Mike’s shoulder was built so that it demonstrates all of the features of McCord Hall’s windows — right down to the separation that will occur in the glass panes where the windows span floors. Yes – we’ll have multi-story-tall windows in McCord. A model window will be installed in the mock up during the week of May14.
The mock-up will also allow everyone a preview of what the brick, laid in a corduroy pattern, will look like on the building. By the time that’s finished, later in May, the New York design architects, Kohn Pedersen Fox Associates, will be in Tempe. Any design or functional issues that are revealed by the mock up will be resolved then.
For the rest of us, the mock-up is nothing more – or less – than another tantalizing glimpse of what’s to come.