Coating formulation for curtain coating fibrous non-woven mats

A construction board comprising:

• a core layer having a first face and a second face;
• and
• a coated non-woven mat having a first major surface and a second major surface, opposite to and having a surface roughness greater than the first surface, defining a thickness therebetween, the first surface of the non-woven precursor mat being adhered to the first face of the core layer, wherein the coated non-woven mat comprises:
• a non-woven precursor mat including a plurality of randomly oriented fibers bound by a precursor binder composition, and
• a coating composition applied to the first major surface or the second major surface of the non-woven precursor mat and substantially uniformly penetrating 5% to less than 30% of the thickness of the non-woven precursor mat, said coating composition comprises about 90 wt. % to about 93 wt. % solids of a mineral filler having a median particle size of less than 5 microns, an organic latex binder composition, and about 0.01 wt. % to about 5.0 wt. % solids of a rheology modifier, wherein the rheology modifier comprises polyacrylamide, anionic polyacrylate, anionic polyacrylamide copolymer, nonionic polyether, nonionic hydrophobically modified polyethylene oxide urethane copolymer, hydrophobically modified cellulose ethers, or mixtures thereof;
• wherein the coating composition is applied to the non-woven precursor mat in an amount between 1.0 and 10.0 lbs/100 ft2.