Phoenix warehouse accelerated corrosion during construction

Million-square-foot warehouse roof. Insulation got wet during construction rainstorm; deck closure trapped moisture in an 8-inch greenhouse cavity under Arizona sun. Corrosion rate of 20 mils/year (5× typical) perforated 1/16" sheet metal within three years.

It was a big warehouse, about a million square foot warehouse, and they had a big rainstorm in Phoenix while they were building this, and all the insulation got wet before they put the decking on. So what did they do? They put the decking on, and they had a bottom seal, so they had about an 8-inch height in that ceiling, of a little greenhouse. The sun would come out — did you know the sun comes out in Phoenix, Arizona? — and it gets hot. Every day and every night they basically would just bathe this in wet, hot water. They actually had twenty thousandths of an inch a year. The galvanizing went away in a few months. Then this sheet metal, which was only sixteenth of an inch thick — twenty thousandths of an inch a year, within three years they had holes in their sheet metal. A leaky roof — it's only a million square feet of roof. And it's because it rained, terrible downpour. Anybody ever seen Phoenix a week after the rain? Beautiful desert blooms. I was in Phoenix once about a week after a rain, and it's beautiful. All it needs is a little water, and that's what they had — their little water.