What types of fasteners should I use to mechanically fasten Grace roofing underlayments?
Grace underlayments that are not self-adhered will require roofing nails or staples both having 1-inch diameter plastic/metal caps. Capped nails or staples may be either machine or hand applied. Nails or staples without caps cannot be used. The fasteners must be spaced at 8 inches on center on both sides and end laps in normal wind zones. In high wind zones or coastal applications, double the fastening to 4 inches on center. Ensure fastening at 24 inches on center down the middle of the roll in the field of the roof.