A steel frame is installed in the doorway. A door is hung on it with hinges. The door is decorated in different ways: leatherette, decorative panel, natural wood, and the latter is considered the most expensive finish. You can also fill the door with soundproofing and heat-insulating fillers. As for the difference in the layers of doors from foreign and domestic manufacturers, it is in the thickness of the steel sheets. That is, imported manufacturers use sheets up to 1.5 mm thick in their products, and domestic ones – 2 – 3 mm..
Yes, domestic doors win in massiveness, but in no way in reliability, since hinges are still responsible for supporting the weight.
Moving on to the filler. It is mandatory, otherwise the door will no longer meet one of the most important requirements: sound and thermal insulation. There are no options: styrofoam, pine beams, backfill and mineral wool. Both polystyrene and pine beams meet the sound insulation criteria to the same extent. But in terms of environmental friendliness, polystyrene loses. “Backfill”, on the contrary, is environmentally friendly and very convenient to use. But she also has a minus. If the work on its installation is not professional, then in the future it can damage the lock. Here, perhaps the most suitable filler will be mineral wool. She is currently in fairly high demand. Mineral wool is environmentally friendly in its composition, and thermal and sound insulation guarantees good quality. There is one more property that is important to note. This cotton wool is resistant to fire and has very low thermal conductivity..
Good advice would be if you make a seal around its perimeter. It additionally protects against blowing, noise, dust contamination and severe friction when the door is closed. A striking example of a door seal has been a padded leatherette roller for a long time. Like all other seals, they are also being improved, so now you can already find modern self-adhesive seals. And it is also recommended to choose kits with platbands and porches. (In imported kits, this is always, in contrast to domestic ones.) These additions will be very useful when protecting against intrusion with a crowbar or crowbar.