Profile: Hambro Roofing Limited specializes in flat roofing. Our workforce consists of trained craftsmen in built-up-felt, mastic asphalt, single ply and liquid membranes such as belzona, kemper & liquid plastics. Roofing felt is a roll of a base material which is impregnated and coated with bitumen or modified bitumen. Mastic asphalt is a waterproofing medium for flat roofs, basements and foundations as well as a surfacing material for floors, pavements, car parks & bridge decks. Single ply membranes are rubber like waterproofing sheets generally defined as either a thermoplastic or elastomeric.