Cloth metal door is a steel sheet (typically thickness 1,5-2,5 mm), reinforced frame (Fig. 1). It is important that sheet was intact, otherwise over time it may be deformed. Outside, as a rule, the canvas is covered with decorative material (some manufacturers offer "anti-vandal" Plastic coating, resistant to mechanical damage) or a special paint. Inside the door must necessarily have a layer of heat and sound insulation. Skeleton forms a welded around the perimeter of the steel blade profile extra ribs – longitudinal and transverse beams.
The quality of the door is not determined by weight and leaf thickness (unlikely someone would cut it by welding in an apartment house), and its rigidity. Than more edges – so it is higher. Ideally, the framework should look like a lattice: due to this design door leaf can not bend. Many manufacturers (eg, Mul-T-Lock) are doing it as a "sandwich" – two steel sheet and frame between them. The door frame is in no case shall the bill be: if the robbers do not even have to open the door, they just spilite her "grinder" and leave the memory of the unlucky owners. With proper installation box is installed inside the opening (Fig. 2) and fastened to it with pins or anchor bolts. There should be no less than three on the right and the left and two on top and bottom. Make a box of step in the cross section profile, and then after concreting it forms a wall of monolithic construction, with no gaps.