Steel doors are often found in commercial buildings but less so in homes. Wood and fiberglass are the two most popular materials for residential entry doors. Yet steel doors can be used for your home and they offer some remarkable advantages. A steel door is not solid steel. Steel doors are comprised of either a polyurethane or polystyrene core with a steel skin over the top.

A solid steel door would be prohibitively heavy and would most likely tear out the hinges. Steel between 16 and 24 gauge is used for the skin of the door.

Pros

Steel doors have a strong outer shell that is difficult to damage if an intruder were attempting to break through the door itself. The steel skin is impervious to most attempts to break through it.

Most steel doors are fire-rated. Steel doors with a 20-gauge skin may be said to have a 20-minute fire rating. For specifics, consult the fire rating sticker on the door itself. Do not assume that all steel doors are fire-rated. Most building codes require that a fire-rated door is installed between the house and the garage.

Cons

Steel doors are difficult for the do-it-yourself homeowner to install due to their weight—but it can be done.

Steel doors' outer shell does not permit sanding and filling with wood putty in the event of scratches or dents.

If anything, you need to think of steel doors as being cousins to automobile bodies, because the way to fix dents in steel doors is to use auto body filler such as Bondo, and then sand down to a smooth, paintable surface.

Steel doors often carry the perception of strength against intruders, when in fact they are no better against intruders than quality fiberglass or wood doors.