Steel security doors are superior in most ways to wooden doors, but they are not always practical. Your existing wooden door may be decorative, it may be a non-standard size, or it may simply be already paid for. When you can’t replace a wooden door, you can sometimes augment it with steel reinforcement.
You’ll need to buy a large steel plate and then drill holes for the doorknob, the peephole, and the mounting screws. The thickness of steel plate depends upon the strength of your door hinges and door material. Here are approximate weights for an average 3′ x6′ 8″ door.
For best appearance, install the steel plate on the inside of the door. Drill holsin the door to match the holes you drilled in the steel plate. Install button headed machine bolts from the outside and cover them with self-tightening nuts on the inside. The button headed bolts are round and provide no gripping surface for attackers.
Don’t upgrade your door and then forget to ensure that the door jam and hinges are equally strong. Also, be sure to remember the additional doors into your home — including the entrance from the garage.