An acoustic damping building material (100, 200, 300) comprising; a substrate having a first face, a second face and an intermediate portion positioned between the first and second faces and an edge portion surrounding the intermediate portion such that the first and second faces, intermediate portion and edge member together form a panel or sheet of predetermined thickness; an acoustic damping layer (118, 218, 318) comprising at least two media (322, 324) wherein one of the at least two media comprises at least one polymeric material and the other of the at least two media is a void volume; and a polymeric binder, wherein the at least one polymeric material and void volume are configured such that the acoustic damping layer comprises at least one direct energy transmission pathway and at least one indirect energy transmission pathway through the acoustic damping layer to the substrate whereby the crumbed and shredded polymeric material of the at least one polymeric material are dispersed amongst each other within the acoustic damping layer such that a portion of the particles or granules of the crumbed and shredded polymeric material are contiguous to an adjacent particle or granule of the same media so as to form a direct energy transmission pathway through the acoustic damping layer and a portion of the particles or granules of the crumbed and shredded polymeric material are contiguous to a void volume so as to form an indirect energy transmission pathway through the acoustic damping layer such that sound energy can be absorbed or transmitted, characterised in that the acoustic damping layer is secured to at least a portion of the first face of the substrate (110, 210, 310) such that the acoustic damping layer does not extend to cover all of the first face of the fibre cement substrate, the at least one polymeric material of the acoustic damping layer comprising a polymeric particulate material or a polymeric granular material selected from the group comprising natural rubbers, nitrile rubbers, butyl rubbers, silicone rubbers, EPDM, synthetic rubbers, polyacrylates, polyurethanes, vinyl polymers, copolymers; wherein the at least one polymeric material is a mixture of crumbed and shredded polymeric material; and wherein the ratio of crumbed to shredded polymeric material is 1:1 and the crumbed and shredded polymeric material comprises 60% ± 2% by weight of the acoustic damping layer, the polymeric binder of the acoustic damping layer further comprising 40% ± 2% by weight of the acoustic damping layer; and the substrate is a fibre cement substrate (110, 210, 310). a substrate having a first face, a second face and an intermediate portion positioned between the first and second faces and an edge portion surrounding the intermediate portion such that the first and second faces, intermediate portion and edge member together form a panel or sheet of predetermined thickness; an acoustic damping layer (118, 218, 318) comprising at least two media (322, 324) wherein one of the at least two media comprises at least one polymeric material and the other of the at least two media is a void volume; and a polymeric binder, wherein the at least one polymeric material and void volume are configured such that the acoustic damping layer comprises at least one direct energy transmission pathway and at least one indirect energy transmission pathway through the acoustic damping layer to the substrate whereby the crumbed and shredded polymeric material of the at least one polymeric material are dispersed amongst each other within the acoustic damping layer such that a portion of the particles or granules of the crumbed and shredded polymeric material are contiguous to an adjacent particle or granule of the same media so as to form a direct energy transmission pathway through the acoustic damping layer and a portion of the particles or granules of the crumbed and shredded polymeric material are contiguous to a void volume so as to form an indirect energy transmission pathway through the acoustic damping layer such that sound energy can be absorbed or transmitted, characterised in that the acoustic damping layer is secured to at least a portion of the first face of the substrate (110, 210, 310) such that the acoustic damping layer does not extend to cover all of the first face of the fibre cement substrate, the at least one polymeric material of the acoustic damping layer comprising a polymeric particulate material or a polymeric granular material selected from the group comprising natural rubbers, nitrile rubbers, butyl rubbers, silicone rubbers, EPDM, synthetic rubbers, polyacrylates, polyurethanes, vinyl polymers, copolymers; wherein the at least one polymeric material is a mixture of crumbed and shredded polymeric material; and wherein the ratio of crumbed to shredded polymeric material is 1:1 and the crumbed and shredded polymeric material comprises 60% ± 2% by weight of the acoustic damping layer, the polymeric binder of the acoustic damping layer further comprising 40% ± 2% by weight of the acoustic damping layer; and the substrate is a fibre cement substrate (110, 210, 310).