A fiber mat comprises: an assembly of fibers comprising a minority portion consisting of a set of polymer fibers and a majority portion consisting of a set of glass fibers, basalt fibers, mineral fibers, or a combination thereof, wherein the minority portion is a plane parallel to a plane of the majority portion of the assembly of fibers; and a binder comprising an organic resin, wherein an air permeability of said fiber mat is not substantially different from an equivalent weight fiber mat containing a homogenous mat structure and wherein the fiber mat provides at least a 5% increase in tear strength when placed in a bituminous roofing product compared to an equivalent bituminous roofing product made with the equivalent weight fiber mat containing the homogenous mat structure, wherein the polymer fibers of the minority portion are present at an amount of less than 10 weight % of the total weight of the assembly of fibers, wherein the fibers of the majority portion are present at an amount of greater than 90 weight %, of the total weight of the assembly of fibers, and wherein the polymer fibers of the minority portion have a melting temperature (T m) greater than 200°C and comprise polyester, polyethylene terephthalate, polyvinyl alcohol, polyvinyl chloride, polyether ether ketone (PEEK), polyether ketone, polyacrylonitrile, polystyrene, nylon, polymethyl methacrylate (PMMA), polybenzimidazole, polyimide, polyether imide, polyamide-imide, polyether sulfone, polyphenyl sulfone (PPSU), polyphenylsulfide, liquid crystal polymer, ethylene tetrafluoroethylene (ETFE), polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane, a blend, or combination thereof. an assembly of fibers comprising a minority portion consisting of a set of polymer fibers and a majority portion consisting of a set of glass fibers, basalt fibers, mineral fibers, or a combination thereof, wherein the minority portion is a plane parallel to a plane of the majority portion of the assembly of fibers; and a binder comprising an organic resin, wherein an air permeability of said fiber mat is not substantially different from an equivalent weight fiber mat containing a homogenous mat structure and wherein the fiber mat provides at least a 5% increase in tear strength when placed in a bituminous roofing product compared to an equivalent bituminous roofing product made with the equivalent weight fiber mat containing the homogenous mat structure, wherein the polymer fibers of the minority portion are present at an amount of less than 10 weight % of the total weight of the assembly of fibers, wherein the fibers of the majority portion are present at an amount of greater than 90 weight %, of the total weight of the assembly of fibers, and wherein the polymer fibers of the minority portion have a melting temperature (T m) greater than 200°C and comprise polyester, polyethylene terephthalate, polyvinyl alcohol, polyvinyl chloride, polyether ether ketone (PEEK), polyether ketone, polyacrylonitrile, polystyrene, nylon, polymethyl methacrylate (PMMA), polybenzimidazole, polyimide, polyether imide, polyamide-imide, polyether sulfone, polyphenyl sulfone (PPSU), polyphenylsulfide, liquid crystal polymer, ethylene tetrafluoroethylene (ETFE), polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane, a blend, or combination thereof.