Steel Door Fire Rating Sticker
Public Domain: NIH
Sometimes I get questions about installing a steel door in a residence, and I thought I would take this opportunity to clear up a few misconceptions that homeowners have about steel doors. Collected below are typical questions that we receive about steel door construction and installation.
Where would I want to install a steel door?
Steel doors are generally installed between interior and exterior areas. They are also typically installed between houses and garages.
Can I install a steel door in a residence?
Yes. Even though steel doors are most often associated with institutional applications (stores, schools, etc.), you are starting to see many more residences with steel doors.
Are steel doors made of solid steel?
No. 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. In addition, a wood frame, called a stile, surrounds the perimeter of the door. So, none of the polyurethane or polystyrene is visible on the edges of the door.
What is the reason for the steel doors’ non-metal core, other than the weight factor?
Remember that steel, and most metals, are remarkably good conductors of heat and cold. This is not something that you want for a door. So the polyurethane or polystyrene cores act as a thermal barriers. In fact, studies show that these man-made materials are 500% better at blocking unwanted heat and cold then are wood doors.
What should I look for when I am buying a steel door?
You want to make sure, for one thing, 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, it is very difficult to cut these through. At the very least, steel doors will come shipped with a factory-applied primer which is ready for manual painting by brush or spray gun. Other steel doors 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 different color.
Are steel doors the same as fire doors?
Not necessarily. Even a wood door can be rated as a fire door. But steel doors generally do have a fire rating. 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. You should know that most building codes require that a fire-rated door be installed between the house and the garage.
Are there any downsides to steel doors?
Steel doors are difficult for the DIY homeowner to install due to their weight--but it can be done. One downside to steel doors is that they do 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.