Concrete construct

Architectural Review, The, Oct, 1997 by D. Day

K. J. McNitt is a construction company that specialises in that particularly American form of construction, tilt-up slabs, and when it decided to build a new headquarters building in Oklahoma City, the company was determined to make the place a demonstration of its expertise in precast concrete. The architects responded with wit and ingenuity by making a building which portrays its construction.

In the normal tilt process, slabs are cast in formwork on the ground then craned or winched vertical, when they are propped temporarily until stiffening elements like the roof and internal walls are in place, after which the props can be removed. Here, the architects decided to retain the props - 4in (100mm) diameter used oil-field pipes - both inside and outside the building. To further emphasise the nature of construction, each 23ft (7m) high panel is separated from the next by an 8in (200mm) wide glazed gap. The joints emphasise the separateness of the panels and their thinness.

Almost all daylight reaches the interior through these vertical glass strips and from rooflights, so the building is scarcely extrovert, but it welcomes the visitor with a formal outdoor entrance court and car park, which is defined on its southern side by the wall of the office building, dramatically articulated by its paired rufous steel tubular buttresses emphasising each glass slit. To the west of the court is a screen wall made of apparently similar panels but here they are cantilevered upwards from an in-situ base and stiffened by external vertical steels; they have air gaps rather than slot windows between each pair and, of course, they are thinner than the slabs used for the office walls because they have no insulation. The plan and section of the rectangular building itself are very simple: a central double-height volume which runs the whole length is flanked on both sides by offices, cellular at ground level, with (as yet) little exploited opportunities for making open-plan spaces above them. The entrance area is at the west end of the plan, with doors and porches at the ends of the north and south walls opening into the double-height central space. As soon as you arrive inside, you are made aware that the directing intelligence is both strange and humorous, for with impeccable logic, the permanent tubular props, which you have already met on the outside, are repeated within, supporting the slabs of the south wall. This time, they are black, slashing dramatically against the predominantly white spaces. What might have been an absurd move has been worked out in section with considerable dexterity, and the diagonal members do not seriously get in your way (though they do reduce the utility of the southern upper gallery), and are responsible for what must be rather annoying holes in some of the desks in the central space. Around these authoritative black accents, the white volumes seem almost ethereal. They are fabricated in the simplest possible ways: the roof is decking supported on exposed lightweight trusses; internal partitions are of drywall panels on metal studs. With a slightly dotty spatial rigour comparable to the structural one, the 8in glazed slots in the external walls are echoed in cuts through the partitions, so that you are subtly made continuously aware of your relationship to the outside, and of being in the middle of an ordered grid of articulated construction. The building does indeed serve its purpose of clearly demonstrating the constructive skills of its owners. But almost anything they built for themselves would probably have done that: the architects have made the result ingenious and memorable. D. DAY