Should every exterior door have a deadbolt?

Neighbors Ask

The plain answer

For nearly every house, a deadbolt on each exterior door is a sensible default. That includes the front door, the back door, the door from the garage into the house and any side door that leads outdoors. If a door leads from the outside world into a place where people sleep, eat or keep their belongings, a deadbolt belongs on it.

There are exceptions, and they are worth thinking about calmly rather than treating as a rule. A door that is hardly ever used might get a different kind of lock. A door that serves as an emergency exit may need a lock that opens easily from inside. A glass door may be better protected by other measures. Rules about exits, fire safety and rental housing vary, so ask your local officials or landlord if there is any doubt.

What follows explains what a deadbolt really does, so you can judge each door of your own on its merits.

What a deadbolt is, exactly

A deadbolt is a lock with a solid metal bolt that slides out of the door edge into the frame. It is called dead because it does not move on its own. A latch, the kind inside an ordinary doorknob, has a beveled tip and a spring. A deadbolt has a square end and no spring, so it stays put until a key or a thumb turn moves it.

That distinction matters. A spring latch can often be pushed back by a thin tool or a determined shove from outside, which is why a doorknob lock alone is a weak defense. A deadbolt, when its bolt is fully thrown and sits in a solid frame, resists that kind of attack far better.

Most residential deadbolts are single cylinder, meaning a key on the outside and a thumb turn on the inside. Some are double cylinder, with a key on both sides. The second type has a safety concern, since you may need a key to get out in an emergency. Local rules about them vary, so check before you consider one.

Why the bolt length matters

A deadbolt is only useful if the bolt reaches into something strong. A bolt that sticks out half an inch into a thin strip of wood is nearly decorative. A bolt that reaches a full inch into solid framing is much more serious. Locksmiths usually recommend a bolt throw of at least one inch, and you can measure yours by turning the key and noting how far it extends.

The part that receives the bolt is the strike plate, and it should be fastened with long screws that reach through the door jamb into the framing behind it. Many homes have short screws holding the strike, and that is the weak point in an otherwise respectable door. Our page on what makes a good strike plate goes into this.

If you take away one idea from this section, make it this one: a good lock set in a flimsy door is like a steel padlock on a paper gate. The whole assembly has to be strong.

Before you go door by door, it helps to ask what a deadbolt is protecting against. Most of the trouble it prevents is simple: someone trying a door that was not locked, or leaning on one that was locked only by a spring latch. A deadbolt does not make a house impenetrable, and no lock does. It raises the effort required and lowers the odds that anyone tries.

The front door

The front door is the most obvious place for a deadbolt, and also the one most often done properly. Make sure the bolt is fully extended whenever you lock it, since a bolt that is only halfway thrown offers little protection. A deadbolt that does not extend fully may be a sign of a misaligned door, which we discuss in why doors sag.

Sidelights and glass panels deserve a mention. If there is a pane next to or in the door, a deadbolt with a thumb turn inside can be reached by someone who breaks the glass. A single cylinder deadbolt placed far enough from the glass, or the glass itself reinforced, helps. A locksmith can look at your layout and suggest something suitable.

Do not forget the screws in the hinges. A long screw in each hinge, reaching into the frame, makes the hinge side as strong as the lock side. It is a small job with a large payoff.

One more thing to check at the front door is the thumb turn. It should turn with a fingertip and not require a wrench of your wrist. If you find yourself bracing against the door to turn it, the bolt is dragging on the strike, and the alignment needs attention. A smooth thumb turn is both a comfort and a safety feature, since you may need to leave in a hurry.

The back and side doors

Back doors tempt people who should not be there, because they are screened from the street. A deadbolt on the back door is just as important as one on the front, and often the back door has the weakest lock in the house. Take a look at yours tonight.

Sliding glass doors need a different approach. They do not take a standard deadbolt, but they can carry a secondary lock, a bar in the track, or a pin that stops the door from being lifted off its rail. We cover that in sliding door security questions. The principle is the same: a second layer where the first is thin.

Side doors that lead to a patio, a carport or a yard also deserve a proper lock. If it is used rarely, you may choose a deadbolt that is key operated on both sides, with the key kept somewhere you can reach it easily. Think about how you would get out in an emergency before you decide.

Picture a family that locks the front door every night but leaves the back door on its knob lock because nobody ever uses it. A neighbor's visitor wanders into the yard, tries the handle out of curiosity, and the family never even learns about it. That is exactly the sort of quiet gap a second deadbolt closes. The scenario is only an illustration, but it shows how the weakest door sets the pace for the whole house.

The door from the garage

The door from the garage into the house is often the forgotten one. People assume the garage is secure, but many garages are open for much of the day, and a door that leads from the garage into the kitchen is an interior door in name and an exterior door in practice.

Treat it like any other exterior door. Fit a deadbolt, check the strike, and make sure the door is solid. Our page on what to do if the lock on a garage entry door fails explains the usual problems with these.

Garage doors themselves have openers and remote codes. Change the code if you have bought a used home, and think about whether a remote left in a parked car is a risk. A deadbolt on the entry door gives you a second line of defense even when the garage has been opened.

If the garage is attached to a room where people sleep, the entry door deserves extra attention. Smoke and fire safety may apply, and so may rules about self closing doors. These vary, so ask a local official or landlord rather than trusting a rule of thumb. A locksmith can fit the lock, but you remain the one who decides what the building needs.

Doors that are different

Some doors should not have a deadbolt, or should have one with special features. A door that is a required exit for a business, for example, usually needs hardware that opens easily from inside, such as panic hardware. We explain that in push bars and panic hardware. Rules vary by building type, so ask local officials or your landlord what applies.

Rental units add another layer. A landlord may control the lock, and tenants may need permission to change anything. If you rent, read what renters should ask a landlord about lock changes before you buy hardware.

Doors for older relatives, young children or people with limited mobility may call for a thumb turn that is large and easy to grip, or a keypad lock that avoids keys altogether. Comfort and safety belong together, and a lock nobody can operate under stress is not much of a lock.

Interior doors are a separate matter. Bedroom and bathroom doors often take privacy locks that are not meant to provide security, and they should not be confused with the deadbolts discussed here. Those small locks can be opened by a simple tool from outside, which is intentional, since they exist so that a child or an adult in trouble can be reached.

• Check that every exterior door has a bolt that extends a full inch or so into the frame.
• Replace short strike plate screws with long ones that reach the framing.
• Match the lock to how the door is really used, including an easy exit in an emergency.
• Treat the garage entry door the same as the front door.

Weather, wear and the Shasta region

Our climate asks a lot of doors. Hot dry summers can shrink and warp wood and dry out lubricants, and snow and cold in the mountain towns can stiffen bolts and swell frames when moisture is present. A deadbolt that slid easily in July may drag in January, and that drag is a clue that the door needs adjustment, not force.

If your bolt has started to feel stiff, do not keep forcing it. Read why does my lock turn so hard and look at the alignment first. A bolt that only lines up when you lift the door a little is telling you something.

In both valley and mountain homes, a seasonal check is worthwhile. Once in the spring and once in the fall, lock and unlock each door, look at the bolt, and make sure the strike is tight. It takes a few minutes and saves a lot of trouble.

Wood doors in our hot dry valley summers can shrink and open slight gaps at the edges, and wood doors in the cold mountain towns can swell and rub. A locksmith looking at your door will often check the gap around the whole edge, because an uneven gap means the bolt is landing in a different spot at different times of year.

Finally, remember the human side. A deadbolt only works if it is used. Make locking up part of the evening routine, the same way you turn off the stove and the porch light, and teach everyone in the household how the thumb turn works. The most expensive lock in the world does nothing on an unlocked door.

Beyond the deadbolt

A deadbolt is one part of a door's defense. The door itself matters: a solid core door is more resistant than a hollow one. The frame matters: a cracked jamb defeats even a fine bolt. The hinges matter, as do the screws and the way the door was hung. Even a good light and a clear view make a difference, since most people prefer not to be seen.

Some people add a second deadbolt on the same door or a heavy duty latch guard that reinforces the area around the lock. These additions can help, particularly on older doors. A locksmith can walk around your home with you and point out which doors would benefit most.

If you are curious how quality is measured, our page on lock grade explains the ratings that manufacturers use, without any need to memorize numbers.

If you are shopping for hardware yourself, look for a solid metal bolt, a thick strike plate and a lock body that does not feel hollow or flimsy in the hand. Weight is not everything, but a deadbolt that feels flimsy usually is. Remember that the hardware store aisle will show many choices, and the grade of a lock tells you more than the picture on the box.

A final thought for anyone who rents or shares a building: lock decisions often belong to someone else. A friendly note to a landlord, with a clear request and a reason, usually goes better than a surprise. Ask, wait for an answer, and keep a copy of what was agreed.

Getting the work done

If you are adding deadbolts to doors that have none, a locksmith drills the door to fit the lock and bolt, installs the strike and tests everything. It is more precise than it looks, since a bolt that misses its hole by a hair causes trouble for years. Our new lock installation page describes the process.

If you already have deadbolts but want them keyed alike or changed after a move, the job is a rekey. And if you are not sure what you have, home lock service covers an assessment of your doors.

Redding Mobile Locksmith works across Shasta and Siskiyou counties, including Redding, Shasta Lake and Yreka. The phone line is coming soon, so please send details through the form on the contact page.

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