Farm building 3000 sq foot metal roof with a 3/12 pitch. Metal over 3/4 plywood. Water shows up somewhat lower than the peak. The homeowner wants to know what to look for when he goes up there. He also believes there is no paper or anything under the metal. He also wants to cut in vent for plumbing and want to know best practice. He is adding a bathroom and the leaks that havn't been important until the bathroom idea came up The building is five or six years old.