Cut a steel door in half and the specification stops being a marketing claim. You see the outer sheet, the edge fold, the internal reinforcement, the core, the inner sheet and the surface finish. Every one of those layers is a separate purchasing decision, and together they decide weight, acoustics and how the door looks after ten winters.

Sheet steel: leaf and frame

The body is formed from cold-rolled steel sheet. Leaf faces commonly fall between 0.8 and 1.2 mm, while frames use heavier gauge because the hinges, strike plate and wall anchors all load the frame. Thickness alone proves little. A leaf with a shallow edge fold and no internal profiles flexes under hand pressure even at 1.2 mm. Ask whether vertical and horizontal reinforcement profiles run inside the leaf; that is what stops twisting and keeps the lock area from denting.

Core material

  • Rock wool: non-combustible, best acoustic absorption. Standard for fire doors and for apartment entrances where noise matters. It adds weight, so hinge sizing follows.
  • Polyurethane: the strongest thermal performer. Suited to exterior openings and unheated stairwells, weaker on sound.
  • EPS: light and economical, acceptable on heat, poor on sound.
  • Honeycomb board: stiffening only, no real insulation value. Not for exterior use.

Surface finishes

PVC membrane pressed onto MDF gives the widest pattern range and carries embossed and laser-cut detail. Oven-baked lacquer on MDF gives flat matte surfaces and is what most white steel doors use. High-pressure laminate and composite panels resist UV, rain and scratching, which is why composite door panels are specified for villa and lobby entrances. Electrostatic powder coating goes straight onto the steel and is baked at around 180-200 °C, with no laminate layer to lift; it is the standard finish on fire doors and pressed sheet panel doors.

Hardware

Two things decide real resistance: how many points the door locks at, and how deep the bolts travel into the frame. A three-point system outperforms a thicker leaf locking at one point. Look for a steel escutcheon against cylinder pulling, a hardened plate in front of the lock case, and fixed security pins on the hinge side that engage the frame when the door is shut. Three-way adjustable hinges let an installer correct rubbing without removing the door.

Seals and dimensions

Most sound and smell transfer happens at the leaf-to-frame line, so two rows of EPDM gasket beat one by a noticeable margin. An automatic drop seal at the bottom seats when the door closes and lifts clear when it opens. On dimensions, be explicit about which figure you are quoting. Our standard apartment door is 90×200 cm clear frame opening, which becomes 108×210 cm at the architrave edge with a 10 cm casing. Villa and lobby doors run 145×215 cm clear, 165×223 cm at the architrave, with frame depth adjustable between 20 and 24 cm.

Buying from Türkiye

For export orders we need the wall opening in centimetres, the hand of the door, the finish family and the hardware level. Doors are crated with edge protection and corner guards, loaded in Istanbul, and shipped by road to Europe and the Balkans or by container to Gulf, North African and overseas markets. Mixed containers are normal: apartment doors, a lobby set and fire doors can travel together on one order. Send drawings or photographs of the openings and we will price to your sizes rather than to a catalogue list.