What a Steel Door Is
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. A wood frame, called a stile, surrounds the perimeter of the door. None of the polyurethane or polystyrene is visible on the edges of the door. Other than the weight factor, steel and most metals are remarkably good conductors of heat and cold. Thermal conduction is not a desired quality for a door. The polyurethane or polystyrene core acts as a thermal barrier. Studies show that some of these synthetic materials are up to five times better at blocking unwanted heat and cold than wood doors.
Where to Install a Steel Door
Steel doors can be installed between interior and exterior areas, but mostly they are used as entry doors that lead to the exterior. Steel doors are typically installed between houses and garages. When steel doors are installed in interior-to-interior spaces it is because of a need for security or fire protection in one of those areas.
Factors to Consider When Buying a Steel Door
Cut-Outs
Make sure that the door has all of the cutouts that you want. If you buy a solid door and then later decide that you want a window or a pet door, you’ll find that it is very difficult to cut through the door. Hiring a door installer will be the best way to add cut-outs to a steel door.
Coating
Steel doors come shipped with a factory-applied primer that is ready for manual painting by brush or spray gun. Others have an additional PVC vinyl layer adhered to the steel skin which gives the door a certain look or color, typically woodgrain. It should be noted that these PVC vinyl layers are hard to paint if you later decide that you want a different color.
Weather
Steel doors are on par with fiberglass and wood for resisting weather. So, if weather-tightness is your main concern, don’t look to steel doors simply because of this factor. You’re better off installing a storm door in front of the steel door to resist against the weather.
Scratching
If you have a dog or other pet that likes to scratch doors, steel doors should resist this type of scratching. But when it comes to metal scratches, steel doors definitely will scratch. Removing those scratches can be difficult. Repainting is often the only fix for a scratched steel door.
Pros and Cons of Steel Doors
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. If a steel door is used with a steel frame, it will be more secure than wood, fiberglass, or steel in a wood jamb/frame.
