Superdome roof getting a good scrubbing to remove mildew

Published: Wednesday, September 01, 2010, 8:15 PM

Bruce Nolan, The Times-Picayune
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The job is enormous and the view spectacular, but at the end of the day the work is pretty ordinary: Like other New Orleanians caring for their driveways or decks, private crews atop the Superdome are pressure-washing mildew off the 9.6-acre landmark.

Enlarge John McCusker The roof of the Superdome is being spruced up in time for the start of the NFL regular season Wednesday, September 1, 2010. Superdome Roof: What's all that gunk? gallery (8 photos)

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The distinctive white roof needs it. The section that has been cleaned contrasts sharply with the streaked and dingy area still untouched.

The $87,500 job should be done by the middle of next week, in time for the New Orleans Saints' regular-season opener against the Minnesota Vikings on Sept. 9, said Doug Thornton, senior vice president of SMG, the company that manages the Superdome and the New Orleans Arena.

Thornton said Superdome managers noticed a few months ago that the domed roof was getting dirty much faster than normal. Ordinarily, it's 18 to 24 months between cleanings. This time, the roof looked bad in 14 months, he said.

A lab analysis showed there was nothing unusual about the grime: It's ordinary dirt and South Louisiana mildew discoloring the Superdome.

View full sizeJohn McCusker, The Times-PicayuneThe pitch of the Superdome roof increases to a 12 percent grade where it meets the gutters around its base.

Thornton said the texture up there is rough and coarse, giving mildew a good surface to bloom in a very wet, humid summer. The Claiborne Avenue side is the dirtiest because it remains in shadow longer, and the morning sun dries the eastern half of the roof.

This roof -- the 35-year-old building's third -- is a replacement for the rubberized roof that was peeled back by Hurricane Katrina in 2005. It's made of two and a half inches of polyurethane foam blown over the metal decking, then sealed with a thin polyurethane coating.

Thornton and operations director Randy Philipson said crews are blasting the roof with tap water at about 3,500 pounds per square inch, comparable to that from pressure washers at any home improvement store.

Each day the crews climb out of a hatch 270 feet above street level at the Superdome's north pole and work at the end of tethered harnesses. The pitch of the roof increases steadily, steepening to a 12 percent grade, where it meets the gutters around its base, Thornton said.

Thornton said the contractor, Brazos Urethane Inc. -- which installed the roof after Hurricane Katrina -- is investigating whether it might be effective to spray a mildew retardant, but that still is to be determined.