Mineral wool insulation board system with mechanical fasteners and reinforcing mesh

A method of constructing an exterior insulated wall, the method comprising:

• erecting a wall structure comprising a plurality of vertical studs in a horizontally spaced apart array and sheathing mounted to the studs defining a vertical substrate surface;
• applying a moisture barrier layer over the substrate surface;
• applying an adhesive layer over the moisture barrier layer;
• mounting a rear surface of a mineral wool insulation board to the adhesive layer, the rear surface having vertically extending drainage grooves defining a plurality of bosses whereby the bosses engage the adhesive layer and the drainage grooves define moisture flow channels between the mineral wool insulation board and the adhesive layer, a front surface of the mineral wool insulation board including a reinforcing mesh adhered thereto;
• securing the mineral wool insulation board to the studs with corrosion resistant screws and washers, the washers engaging the reinforcing mesh, the screws extending through the reinforcing mesh and the bosses of the mineral wool insulation board, through the adhesive and moisture barriers, and through the sheathing into the studs;
• and
• applying a weather resistant coating on the reinforcing mesh and washers;
• wherein the mineral wool insulation board comprises mechanically entangled non-woven hydrophobic fibers spaced apart by air voids to define a compressible fibrous mass;
• wherein the mechanically entangled non-woven hydrophobic fibers are oriented generally parallel to the vertical substrate surface;
• and
• wherein the washers and screws exert pressure on a compressed zone of the compressible fibrous mass adjacent to the screws and beneath the washers, the compressed zone having a reduced moisture permeability with a higher volume percentage of fibers and a lower volume percentage of air voids relative to a non-compressed remainder of the compressible fibrous mass, and wherein the washers and screws exert pressure on the compressed zone of the fibrous mass at a location of at least one of the plurality of bosses, the fibers of the compressed zone being configured to impede water flow around the screws;
• wherein the mechanically entangled non-woven hydrophobic fibers oriented generally parallel to the vertical substrate surface define a flow path through the non-compressed remainder of the compressible fibrous mass to the moisture flow channels between the mineral wool insulation board and the adhesive layer.