Fiberglass Sheathing refers to gypsum panels with fiberglass mat faces. Fiberglass sheathing is considered to have superior moisture and mold resistance in comparison to paper face only sheathing. Fiberglass sheathing is primarily used on exterior walls and is an acceptable substrate for just about any material type. It is perhaps most commonly utilized as a substrate for Stucco and EIFS systems. It is also used with brick, shingles, shakes, vinyl, metal, wood, and fiber cement. Fiberglass sheathing is also able to resist destructive winds and flying objects better than some other cladding systems. Commonly sold and utilized thicknesses are 1/2″ and 5/8″ with 5/8″ often being considered and marketed as fire-resistant. Stock sheets commonly come in 4×8, 4×9, and 4×10 but can be had in custom sizes as well. Fiberglass sheathing is also popular for being moisture resistant during installation, more so than plywood or OSB. It is also more resistant to delamination, deterioration, sagging, and warping. It weighs approximately 10-13% more than gypsum sheathing. It can be installed vertically or horizontally with fasteners driven flush with the surface, and 3/8″ or more away from any edge. The following are fastener types commonly recommended with fiberglass sheathing depending on the substrate:

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