How Do You Build A Vapor Barrier For A Metal Roof?
A vapor barrier is used to block moisture diffusion through concrete or ceilings. Vapor barriers are usually foil or plastic sheets laid out over a structure as a protective lining. The vapor barrier on a roof structure prevents water vapor from rising up from the house and rotting the roof structure. All types of roofs need a vapor barrier, even a metal roof. A vapor barrier serves as a type of insulation against harsh weather extremes and can preserve the life of your metal roof. Measure and cut 3-inch fiberglass insulation with a vinyl face. You can buy this product at most hardware and roofing stores. The rolls come 6 feet wide. Overlap the seams when placing the sheets on the roofing plywood, and staple them down with 3/8-inch staples and a slap stapler. Nail down 2-by-4 boards from the ridge beam down to the eaves, placed every 16 inches. These are the spacers needed for proper ventilation between the roofing plywood layers. Use 16-penny nails and a hammer. Hammer a nail every 12
