How to Reinforce Door With Knob Reinforcer

Wrap-around metal plates strengthen exterior doors against break-ins.

This story walks you through the how to steps to install a doorknob reinforcer on your exterior doors. It's a simple, inexpensive project that makes your entry door more secure and less vulnerable to break-ins.

By the DIY experts of The Family Handyman Magazine






Under $20

Install the doorknob reinforcer

Install a door reinforcer on your entry and garage service doors to help discourage break-ins.

Reinforcers are three-sided metal plates that encase and strengthen the door around the latch, which is a door's most vulnerable area. The reinforcer shown is meant to strengthen door latches (Photo 3), but you can also buy reinforcers that strengthen deadbolts. Install them on fiberglass, wood or steel doors as shown in Photos 1 – 4.

A reinforcer extends the door edge about 1/32 in., and so may rub the door frame of tight-fitting doors. If so, slightly deepen the hinge mortises with a chisel to widen the gap at the latch side. Or chisel a 1/32-in. recess into the door edge so the reinforcer fits flush. Door reinforcers are found at home centers and well-stocked hardware stores.

Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Cordless drill
  • Tape measure
  • 4-in-1 screwdriver
  • Drill bit set

The drill bit you'll need is a 3/32 in. bit. Any drill or flathead screwdriver will work if you don't have a cordless drill or 4 in 1 screwdriver.

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

  • Doorknob reinforcer

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