It is worth soundproofing and strengthening the entrance door to the apartments. We soundproof them with a sheet of polyurethane sponge. Before that, we have to screw a frame made of slats or metal profiles to the door leaf, which at the same time will strengthen the door against breaking through. Inside such a border we put a piece of sponge, and then we cover it with a piece of artificial leather. In addition to reinforcement with profiles, protection against an easy break-in will be by screwing a steel sheet with a thickness to the leaf 1 mm.