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Expert Contributor

Whether you’re dealing with cover wood, fiberglass or steel doors, a broken lock is catastrophic. Few security concerns match that of a broken lock. If you’re facing a broken lock — or, if you’re changing the locks altogether — there are a few things you should first understand. Once you’re ready, you can replace the lock yourself. Below is a step-by-step guide to entry door, back door and side door lock replacement.


Buy a New Lock

Trust us: It’ll save you time in the long run. You’ll need to keep an extra lock handy before replacing the old one. Check your door’s latch, and identify your lock’s brand. If you purchase the same brand, you won’t need to make any adjustments to the existing holes.


Get the Measurements

Next, you’ll need to measure the lock’s width. Measure the space between the door’s latch and the middle of the doorknob. Most exterior doors have a diameter of 2 ¾ inches, or 6.5 centimeters.

To measure the lock’s height, measure the space between the lock and the door’s finish. It’ll likely be the same height as the width since most locks are perfect circles.


Remove the Lock

Lock removal is simple. On wood and fiberglass doors, remove the old lock’s screws from the inside of the door. If you’re dealing with a metal door, you may need to first remove an exterior plating. Some metal locks have enhanced bracing for security reasons. With most doors, you’ll only need to remove two to three screws. Most of these screws require a Philips head screwdriver.

Remove the two screws that hold the knob mechanism’s latch, which is located at the edge of the door. The latch can be removed easily, but its screws, sometimes, are small. Make sure they’re handled with care.


Now, It’s Time to Install the New Lock

Your new lock will come with a cardboard installation template. Simply wrap the template around the door’s edge and knob hole. If the template doesn’t match up with your door’s hole, you may have purchased the wrong lock. In this case, return the lock for one that's the correct size.

Latch Installation

First, you’ll need to install the new latch. Place it into the old latch’s slot. If possible, reuse your old screws. Simply insert them through the new latch’s holes, into the door’s edge, and tighten them with a Philips head screwdriver. You can be liberal with tightening the screws if you’re working on a metal door. If you’re working on aged wood or old fiberglass, however, be careful. Sometimes, screw holes can be stripped. Be gentle when guiding the screws in.

Knob and Lock Installation

Once you’ve installed the latch, you can install the knob and lock. Insert half of the lock and doorknob mechanism through the door’s exterior. Feed it through the center of the door. Then, insert the other half through the back. The pieces will meet in the middle and attach. If they don’t connect, wiggle them around. Don’t force the pieces, however, as the mechanism’s internal metal can bend if too much pressure is applied. Once you’ve connected the pieces, tighten the interior screws.


Deadbolt Installation

If traditional locks don’t meet your security concerns, consider installing a deadbolt. Sometimes, spring-loaded doorknobs don’t offer enough protection. Fortunately, deadbolt installation is easy.

First, purchase a deadbolt. Make sure you’re purchasing a mechanism that meets your door’s needs. Metal door deadbolts, often, are more “industrial” in design. They offer more security, too. Deadbolts suited for wood and fiberglass doors, however, may have different hole configurations, designed to protect the door’s structural integrity as it’s installed.

Marking and Drilling the Spot

As with a traditional door lock, your deadbolt will arrive with a manufacturer’s template. Line the template up with your door six inches above your door’s knob. Once you’ve market the reference template, use a hole saw to cut the deadbolt’s hole. Then, finish the hole.

Next, mark and drill the template’s mark on the door’s side — where the bolt will enter the wall. Once you’ve done this, dry-fit the bolt into the hole. Trace around the deadbolt’s faceplate, and use a wood chisel to mortise the surrounding area.

Installing the Deadbolt

First, install the deadbolt’s exterior end. Then, connect the interior piece. Align the screw holes with care, and fasten the deadbolt. Installing a deadbolt on a front door is similar to installing a traditional lock. Simply align the pieces, tighten the screws, and test it.

It’s a good idea to check your home’s locks occasionally. While most door locks offer decades of security, locks age when facing year-to-year use, forceful contact and even bad weather. If you’re worried about installing a new lock, contact a professional locksmith. Take your time during installation, and don’t be afraid to ask for help. Two sets of eyes are better than one.


Robert G. is an independent contractor and article writer focusing on information-savvy approaches to various industries. With a well-rounded approach to a wide array of topics, Robert enjoys research and revisions to deliver quality content with quick turnaround times to serve tight schedules.