We didn't get any background on this problem. Is this a new shop building? I did some work for a neighbor a few years ago, he had bought a house that was built at a yard, where a company builds new homes, then moves them. The siding went bad, it was part of the Masonite company's bankruptcy, and I resided the house with Hardy board. The neighbor tore the old siding off, and then I put the new siding on. After I had it finished, he called up and said his plumbing was leaking when he ran the washing machine. So I went over, cut a hole in the drywall where the leak was, and found holes on the outside of the pipe. When I got the pipe out, I found double holes from staples in the side facing the outside, and found that they had sided the house after the plumbing was installed, and they shot staples through the plumbing from the outside. Could a similar thing have happened that caused your problem?