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The Ultimate Guide to Reinforcing Your Doors

12 Mar 2019
Derek Crippin

How do most burglars enter homes?

The answer may surprise you. They aren't sneaking down the chimney or digging their way into your basement; most of them simply walk right up to your door and smash their way through it.

Let's look at some statistics:

  • 34% of burglars break in through the front door
  • 22% gain entry using the back door
  • 9% get in via the garage

In short: 65% of all burglaries involve a criminal being able to defeat your door security.

The best place to start securing your perimeter is by focusing on your first line of defense: exterior doors.

Is your door strong enough?

A common issue we see in many homes is people using an interior door on an exterior entry point.

An interior door is one like you would most likely find on your bedroom or bathroom door.

Hollow-core doors like these are usually made of some kind of thin veneer with a hollow center and designed for privacy, not security.

hollow core solid core door

You can put the best locks in the world on this type of door, but it won’t do you any good if a 12-year-old can kick through it at the door’s weak points.

Replace any hollow-core doors with metal-insulated or solid-wood doors. These will be much more resistant to burglar attacks.

Reinforcing Your Door

Armor Concepts make a door reinforcer called Door Armor -- essentially, a metal sleeve that bolts around the door in the area of the doorknob and deadbolt to give that part of the door additional strength.

door armor

This helps to prevent the door from breaking in the area of the lock, such as in a kicking or prying type attack.

This product can also be used to temporarily secure a door that has been recently broken into, giving it some strength until a new door can be installed.


As surprising as it may sound, many burglaries happen to homes that were left unlocked. The burglar didn’t have to "break" in at all; just turn the doorknob.

Sometimes people make burglars’ lives even easier by not closing the door in the first place. Talk about an open invitation.

It’s more common to leave garage doors open, but police tell us they frequently encounter cases where apartment doors, dorm doors and house doors have been left standing open, and a burglar was able to seize the opportunity.

Obviously then, the first things to do would seem to be to close your doors and use the locks that you currently have. Any lock is better than no lock.

But some locks aren’t much better than nothing. You’ve got to have the right type of lock on your door if you want any protection at all.

Knob Lock

One type of lock is the knob lock. This has a key slot in the doorknob on the outside, and a thumb turn or some kind of button on the inside doorknob.

knob lock

If a knob lock is your only protection on the door, your home may be vulnerable. Here’s why:

  • The locking mechanism is in the door knob itself, which is vulnerable. All a burglar needs to do is saw off the door knob, knock it off with a hammer, or twist it off with a pair of pliers. Once that’s out of the way, it just takes a bit of finesse with the needle-nose pliers or screwdriver to open your door.
  • Another problem with the knob lock is that the latch is too short. A burglar can defeat this type of lock by a shim type attack, like using a credit card or similar object to push the latch back and open the door. Or the burglar can use a "spreading" type attack, prying the door open with a large screwdriver or wrecking bar.
  • Lastly, it may be possible to kick the door open, because the latch is so short and it doesn’t go deep enough into the strike plate to hold solidly when any real force is applied.

Add A Single-Cylinder Deadbolt

If all you’ve got on your door is a knob lock, you can add a second layer of protection with a deadbolt lock positioned 6" to 8" above or below your doorknob.

single cylinder deadbolt

A single-cylinder deadbolt has a key slot on the outside, and a thumb-turn on the inside. When you fully extend the deadbolt, you can’t push the bolt back in, like you may be able to do with a knob lock. This prevents someone from using a knife or other sharp object to pry the bolt back and open the door.

Look for a deadbolt that has a bolt that is a minimum of 1" when fully extended. Also, look for a lock that has a tapered cylinder guard. The slot you stick the key into is called the cylinder. The piece of metal that goes around the cylinder is the cylinder guard.

cylinder guard

This should be tapered which means it should be wider around the part that goes up against the door, and narrower toward the front where the key would go.

This makes harder for someone to try to chisel or drill into the cylinder guard. The cylinder guard should be free spinning, which means you can twist it or spin it around and around without doing any damage, preventing someone from unscrewing the cylinder guard and removing the lock.

Deadbolt Lock Advantages

  • First, the locking mechanism is protected because it is inside the door where it can’t simply be smashed off.

  • The deadbolt can’t be pushed back in after it’s fully extended, reducing the chance a burglar will be able to open the door with a shimming attack.

  • The deadbolt is longer than the latch on the knob lock, it will be harder for a burglar to "spread" the door and pry it open.

  • The deadbolt goes far enough into the doorjamb wood and strike plate to hold in the event of a kick (provided the strike plate is properly installed, which we’ll discuss in a minute.)

How to Choose a Deadbolt Lock

When buying a deadbolt lock, it’s important to choose quality over price. Sure, there are $8 deadbolts available at discount stores, but it’s important to look for a lock that meets the  specifications outlined to adequately protect you.

Do you often forget to lock your deadbolts? Get a smart deadbolt instead.

With the Yale Assure Lock Touchscreen Keypad, you can lock and unlock your doors via your phone. That way, even if you leave for work one morning and forget to lock the door behind you, all you need to do is pull up your app and enable the lock with a single button.


Plus, your family members can all punch in their unique pass codes that give them keyless entry. Want to let in a housekeeper or rent out your home for Airbnb? Allow guests temporary access with key codes that expire after a set period; no more handing out spare keys.


Recently there has been a lot of buzz on the internet about key-bumping to unlock deadbolt locks without damaging them.

Locksmiths have been doing this for decades, but in recent years lockpicking enthusiasts have produced all sorts of YouTube videos, instructions and tools enabling anyone to open most ordinary deadbolts with ease.

bumping keysA set of bumping keys.

In a nutshell, a special "bump key" is inserted into the lock, and it's struck with a plastic hammer. This causes the tumbler pins to fly up in a random fashion and after a couple of whacks the pins line up correctly and the lock can be opened.

Quality Deadbolts Are Effective

If you really want to protect your family, yourself and your possessions, it’s a good idea to invest in high security deadbolts such as the Medeco Maxum Residential Deadbolt.


Once used primarily for protecting nuclear power plants, laboratories or government facilities, Medeco high security deadbolts are now being used in more residential settings to combat the fear of key-bumping.

Let’s get technical. This Medeco lock exceeds ANSI (American National Standards Institute) Grade 1 standard for auxiliary locks. Grade 1 is the highest rating. This lock features a free turning collar making it resistant to attacks from tools like pipe wrenches or cold chisels, and 1/4 inch diameter mounting bolts which resist wrenching, prying and hammering attacks.

It has a hardened steel bolt that is one inch when fully extended, which is what you want, making it resistant to sawing and crowbar attacks. There are also hardened steel inserts and pins that rotate which it makes it that much harder to pick or drill in accordance with Underwriters Laboratories UL 437 standard.

The Biaxial® design offers a utility patent that provides protection against unauthorized key duplication. In other words, no hardware store will be able to make a duplicate key unless you authorize it.

This lock comes with a high security strike plate that has a special box design with 2" screws which anchor the strike directly to the building structure behind the frame, making it very resistant to "kick-in" type attacks.

The heavy gauge tubular steel housing surrounds the hardened steel bolt and bolt throwing mechanism, providing maximum resistance to crowbar type attacks. The whole solid brass design lock is held together with high-tensile steel mounting bolts for greatest resistance against hammer and prying attacks.

This lock has a lot going on that makes it so resistant to picking: a special rotating and elevating pin tumbler design, false slots on the bottom pins, mushroom top pins and a sidebar mechanism. This is also what makes this lock so resistant to key bumping.

If all this weren't enough, it is very difficult to defeat this lock by drilling due to hardened steel inserts, positioned in critical areas of the cylinder.

What About A Window in or Near My Door?

If you’ve got a window in your door or very close to it, you’ve got a potential problem. The rule of thumb is that if you have glass within 40" of your thumb-turn, you’ve got to do something. Here’s why.

If a burglar breaks the glass in your door, all he has to do is reach in and turn the thumb-turn to open your door.

exterior door with window

The best thing to do is to replace that door with one that doesn’t have a window. And, while you may lose some of the aesthetic value of having a window, you’ll be safer against this type of invasion.

Another more extreme option is to put bars or grates over your window. In fact, in higher crime rate areas you’ll see bars or grates over all the windows.

Before you do that, consult your state's fire code to be sure it’s legal. In some areas of the country you may be prohibited from putting bars over bedroom windows.

This is so that if there is a fire, the firemen will be able to get you out, and if the firemen are in your house battling a blaze they know they’ll be able to get out through a bedroom window.

Double-Cylinder Deadbolt

Some people will install a double-cylinder deadbolt if there is glass within 40" of the lock. A double-cylinder deadbolt has a key slot on the outside and a key slot on the inside, instead of a thumb turn.

master lock dual cylinder deadbolt

Here’s the theory: You leave the house. You put the key in the slot from the outside and lock your door. Along comes a burglar. He breaks your window, and reaches in, but because there is no thumb-turn to open on the inside, he can’t get in.

The trouble begins when you are home. You get ready to go to bed. You go over to the door to lock it. There is no thumb turn on the inside remember, so you have to insert your key into the slot and you lock the door. You go to bed. Meanwhile your child, or someone else comes along and takes the key out of the slot.

Three hours later, you wake up in a smoke filled house when your smoke detector is going off. You manage to stumble your way to the front door, but you can’t get the door unlocked because there is no thumb-turn and the key isn’t in the slot.

While double-cylinder deadbolts are a powerful security measure, they can also put you in danger in an emergency because of their design.

There is another variation of this lock  --a double-cylinder deadbolt with a key retention feature.  These are similar to the standard double-cylinder deadbolts, except when you want to  remove the key from the slot, the only way it will come out is to first unlock the door.

In case of emergency, when you get to the door, the door will either be unlocked already, because someone has already removed the key, or the key will still be in the lock so you can unlock the door, same as you would if there was a thumb-turn on the single-cylinder deadbolt.

What happens if a burglar breaks the door window in the middle of the night, when you are asleep? Won’t he be able to reach in, turn the key that is still in the slot on the inside, and unlock the door just like he would with the thumb-turn?

Yes, but it’s a trade off. You’ll likely be able to get out faster in case of a fire.

A final suggestion is to replace the window glass with a piece of polycarbonate resin.

This is available from a glass installer, and is about 300 times more resistant to breakage that a standard windowpane. The downside? It’s more expensive, scratches easier, and may yellow with age.

These windows must be properly installed because, even though it is almost impossible to break, if it isn’t installed properly it is possible to knock the whole piece out of the frame to gain entry.

Once you understand the potential issues presented by using bars, grates, double-cylinder locks, and polycarbonate resin to bolster security if you have a window on or near the door, you can see why replacing is may be the easier and safer option.

Before we leave deadbolts, one last thing having the best lock in the world does no good if it isn’t used.

You might have deadbolt locks on your doors right now. You probably lock the deadbolt at night. But did you lock the deadbolt when you left home this morning? Did you put the key in the slot and lock the deadbolt?

If you did, congratulations. If you didn’t, that deadbolt lock wasn’t doing you any good at all. You were putting all your faith in our old knob-lock, and we’ve already discussed how unreliable it can be.

Locks should be locked when you are away from home, and when you are home. We’ve seen cases where unlocked homes have been entered while the resident was outside working in the backyard, painting, or sunbathing.

We’ve also seen cases where unlocked homes have been entered while the occupants were asleep, in the shower, or in another part of the home. That’s why, while it sounds so simple,  it’s so important to keep your doors (and deadbolts) locked at all times.

Strike Plate

Let’s review. We’ve got decent doors, hinges on the inside where they’re not exposed, and deadbolt locks.

The next critical part of securing our doors is an examination of the strike plate.

The strike plate is the piece of metal that is mounted to the doorjamb. It’s the piece that the deadbolt goes into when the lock is locked. 

strike plate

Here’s the problem with many strike plates --when they were installed, the builder used the tiny ½" screws that came with the strike plate.

When a burglar comes along and kicks your door, even if you’ve got a deadbolt lock, because the strike plate screws are too short, the doorjamb splinters. The door comes open as one piece of the jamb goes flying across the room.

Here’s what you’ll need to do:

  • Check the length of your strike plate screws.

  • Replace the tiny little ones with screws that are 2 ½" to 3"-long. Now the screws not only go into the doorjamb, but they go clear into the door stud, deep enough to hold when the door is kicked.

  • Consider replacing your strike plate with a heavy-duty strike plate such as the Prime-Line U 9539 Armored Security Strike Plate. This will be made of heavier material, and will be larger than the standard strike.

prime line armored security strike plate

Security Chain

Does your door have a security chain? You know, one of those little chains that you can latch and open your door a couple inches, presumably to look out the open crack and still be theoretically safe?

If you have a security chain, don’t count on it to protect you.

door security chain

The problem with the security chain is that it is a vulnerability in disguise. If you unlock your door, the wrong person can easily shove his shoulder up against the door, snapping the chain to gain entry. Police have to do this all the time to gain entrance to homes in emergency police calls.

If you’ve got a security chain, get rid of it and install a peep-hole instead. There are several different styles available now, but the traditional style will give you almost a 180-degree field of view.

Now instead of opening your door a crack to see who is out there, you can look through the peephole, keeping your door locked.

As you will see, you really have a lot of choices. National Hardware N162-362 805 Door Viewer is what I would call your standard fish-eye. It's cheap, effective and easy to install.

national hardware door viewer

One disadvantage is that to look out of it you have to put your eye right up to it. Someone on the outside can see the viewer get dark when this happens, which will tip him to the fact that someone is home.

But there are other high-tech options. VW Optics Wide Angle Peephole Door Viewer Doorscope is designed so you don't have to put your face right up to the door to look out.

wide angle peephold door viewer

It works best at about three to four feet away. This wide-angle viewer will give you a 132 degree viewing area. You’re still going to need adequate outdoor lighting to see who is outside your door clearly at night.

If you want the combined functionality of a peephole and a doorbell, the Skybell HD Video Doorbell will turn your doorbell into a smartphone-integrated video camera.

skybell video doorbell

You can easily see who is at your door without letting them know you are home, ensuring your family’s safety by seeing who’s at your doorstep on any device.

The viewer compensates for lower light levels and the image is easy for anyone of any height to see. There is also a zoom feature allowing you to zoom in for a closer look. There is no "fish eye" distortion as you would find on a traditional door viewer.

Other Options

There are a couple other options for adding additional security to your doors. One is by using a door jammer. This works on the same principle as jamming a chair up under the door knob.

buddybar door jammer

One such device is the Buddybar Door Jammer. This provides your home with an added measure of safety by reinforcing doors from outside intruders.

Constructed with heavy-duty 16 gauge, powder-coated steel and weighing in at 8.2 pounds, the Buddybar sets up quickly and without tools. The foot is 2"x4" rubber coated, steel, articulating, non-marring, which makes for a solid grip.

This is ideal for home, apartment, dorm, while travelling, working late at the office, or anywhere you want extra security. It extends from 36" to 51". It works on carpet, tile, concrete, and wood floors. The Buddybar is the stoutest home security bar currently on the market.

Another option is the GE Personal Security Door Stop Alarm. Weighing only four ounces, it looks like a standard door stop, but this one has a built-in 120 decibel alarm. This not only helps keep intruders out, the alarm will alert you to their presence, giving you more time to react. This item is very easy to use.

ge door stop alarm

The Door Stop Alarm requires no wires or complicated installation and is powered by a single nine-volt battery. Just place the pressure-sensitive Door Stop Alarm at the base of any door, and the device will emit a powerful 120-decibel alarm when the door is opened. In addition, it features a rubber base pad that provides traction on wood, tile, vinyl, and carpet.

With secure gripping ability, the alarm can function as a door stop that prevents a door from being opened. A battery indicator light lets you know when it’s time to change the battery.

This door stop alarm is small enough to be easy to take anywhere. With this little device, you'll be able to secure your hotel room, dorm room, apartment, or any room in your home.


Properly securing your doors is an investment of time, money, and energy. But the protection it provides is incomparable.

Consider this. What is the potential cost of not securing your door? Just remember: when a burglar can’t get in through your door, they’ll try your windows next.

The Ultimate Home Security Guide

A comprehensive list of steps you can take to protect your home and your loved ones.

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