A roofing, cladding or siding module (200, 300) comprising: an underlapping region adapted to be substantially covered by an exposed region of an adjacent overlapping module when installed on an inclined building surface, a plurality of projections formed on an underside of the underlapping region, wherein the projections: (i) are feet to support the module on the inclined building surface to provide a gap between the module (200, 300) and the inclined building surface, and/or (ii) provide a profile on the underside of the underlapping region to define a pathway for air flow between the module (200, 300) and the inclined building surface, each projection formed by a downwardly projecting portion of the underlapping region with a corresponding cavity in an upper side of the underlapping region, wherein the cavity is shaped to prevent or minimize water pooling in the cavity, wherein a surface of the cavity extending between a base of the cavity and a front of the cavity is inclined to allow water to flow from the cavity when the module is located on an inclined building surface, and wherein with the module (200, 300) located on the inclined building surface, an angle between the surface of the cavity and the inclined building surface is less than an angle of incline of the inclined building surface, wherein the module (200, 300) comprises at least two rows of said projections, and wherein the rows are off-set or staggered between a front and rear of the underlapping region. an underlapping region adapted to be substantially covered by an exposed region of an adjacent overlapping module when installed on an inclined building surface, a plurality of projections formed on an underside of the underlapping region, wherein the projections: (i) are feet to support the module on the inclined building surface to provide a gap between the module (200, 300) and the inclined building surface, and/or (ii) provide a profile on the underside of the underlapping region to define a pathway for air flow between the module (200, 300) and the inclined building surface, (i) are feet to support the module on the inclined building surface to provide a gap between the module (200, 300) and the inclined building surface, and/or (ii) provide a profile on the underside of the underlapping region to define a pathway for air flow between the module (200, 300) and the inclined building surface, each projection formed by a downwardly projecting portion of the underlapping region with a corresponding cavity in an upper side of the underlapping region, wherein the cavity is shaped to prevent or minimize water pooling in the cavity, wherein a surface of the cavity extending between a base of the cavity and a front of the cavity is inclined to allow water to flow from the cavity when the module is located on an inclined building surface, and wherein with the module (200, 300) located on the inclined building surface, an angle between the surface of the cavity and the inclined building surface is less than an angle of incline of the inclined building surface, wherein the module (200, 300) comprises at least two rows of said projections, and wherein the rows are off-set or staggered between a front and rear of the underlapping region.