Changing or Installing Locks on Your Doors

When a lock change makes sense

People change locks for many reasons, and each one points to slightly different choices. You may have moved into a new home and want to control who has keys. A lock may be worn, loose or sticking. A key may have been lost or stolen. A break-in may have damaged the door hardware. You may be building or renovating and need locks fitted to new doors. Or you may want better security, a different style or a feature such as a keypad.

Some of these situations call for rekeying, which keeps the hardware and changes the key. Our page on lock rekeying service explains when that is enough. A full lock change replaces the hardware, which makes sense when the lock is worn or damaged, when you want a higher grade of security, when you want a new function or when the style no longer suits the door.

A lock is only as strong as the door and the frame around it. A very good deadbolt fitted into a hollow, weak door with a thin frame provides less protection than it appears. A thoughtful installation looks at the whole assembly: the lock, the strike plate, the door, the frame and the hinges. That is why a lock change is a good time to check the condition of the door itself.

This page walks through the choices and the process. It does not give prices, because quotes are given only by phone after we know what you have and what you want.

The main types of door locks

Understanding the vocabulary helps you ask for the right thing. Residential doors usually carry one or more of the following.

• Knob and lever sets: The handle that opens the door. A passage set has no lock, a privacy set locks from inside, and an entry set locks with a key. These usually control a spring latch, which is a convenience latch and not a strong security device.
• Deadbolts: A solid metal bolt that extends into the frame when the key or thumb turn is operated. Deadbolts are the main security lock on an exterior door. Single cylinder models use a key outside and a thumb turn inside. Double cylinder models use a key on both sides.
• Mortise locks: A heavy duty lock set into a deep pocket in the door edge. Common in older homes and in commercial doors, and often combining latch and bolt in one body.
• Rim locks: A lock mounted on the inside surface of the door, often found on older doors or as an extra lock.
• Smart locks and keypad locks: Locks operated by code, card, phone or fingerprint, often in addition to a key. Our page on smart lock installation covers these.
• Padlocks and hasps: Used on gates, sheds, garages and fences, and rated for different levels of resistance.

What lock grades mean

In the United States, residential door hardware is commonly rated by an industry standard for performance. The grading looks at things like how many times the lock can be operated before it wears out, how much force the bolt and latch can withstand, and how the lock resists certain kinds of attack. Locks are usually sorted into three grades, with the first being the highest.

A top grade lock is built for heavy use and resists a greater amount of force. It is common in commercial buildings and is available for homes. A middle grade lock is a good fit for most houses, with solid construction and reasonable resistance. A lower grade lock meets minimum requirements, and is common as a builder default. Grade is not the only measure of quality, and not every lock states its grade on the package, so it is worth asking the technician what the lock is rated for and what that means in practice.

A grade is a rating for the lock, not a promise about the door. A top grade lock in a weak frame is only as good as the frame. Equally, a lower grade lock does not mean it is unsafe, but if security is a priority, a higher grade is worth discussing.

Brand matters, but less than people think. Many brands make locks across several grades. What matters is the model, the build quality and how well it is installed. A technician can explain the options available for your door and describe the differences. Our page on high security locks explains the next step up, which includes added resistance to certain attacks and controlled keys.

Choosing a deadbolt

The deadbolt is the heart of exterior door security. Three questions guide the choice. First, single or double cylinder? A single cylinder deadbolt has a thumb turn inside, which makes it easy to leave quickly in a fire or emergency. A double cylinder needs a key on both sides, which resists someone breaking a nearby window and reaching in to turn the thumb turn, but it can trap people inside if the key is not at hand. Fire safety guidance and local codes often favor the thumb turn on residential exits, and some jurisdictions restrict double cylinder locks. We recommend checking local rules and asking the technician.

Second, how long is the bolt, which is the throw? A longer throw extends further into the frame and resists being forced. Third, what is the strike plate like? A strike plate secured with long screws into the frame stud is much stronger than one held with short screws in the trim.

Our page on deadbolt installation service discusses these points in more detail, and our guide on how to choose a deadbolt helps you compare options before you call.

Also think about features. Some deadbolts are combined with a handle set, some stand alone. Some have a key that is hard to copy, some use a standard key available at many shops. If you care about key control, ask about restricted keyways. If you want convenience, a keypad option may suit.

Door preparation: the part people forget

Installing a lock means drilling holes in the door and cutting a recess for the latch and the strike. Doors differ, and the preparation depends on what you have. Most residential doors need two holes: a large cross bore for the lock body and a smaller edge bore for the bolt. Standard dimensions apply to most doors, but older, thicker or thinner doors and unusual styles may need adjustment.

A technician checks the door's thickness, the existing holes and the condition of the wood or metal. If you are replacing an existing lock, the holes are often already in place. If the old holes are the wrong size or have been damaged by a previous break-in, they may need to be repaired, for example with a reinforcing plate. If you are adding a new deadbolt where none existed, new holes must be drilled accurately.

The frame matters too. The strike plate sits in the frame, and the bolt goes into a hole behind it. If the frame is weak, split or cut too shallow, the lock will not hold well. A technician may suggest a reinforcing strike plate with long screws that bite into the wall stud, which makes a forced entry much harder.

Doors that are hollow core are common inside homes and sometimes outdoors in older or lower cost construction. They are not suited to heavy exterior security. A technician can advise on whether a door should be replaced. We do not install doors, but we will tell you honestly when the door is the weak point.

Matching hardware to the door

Locks must suit the door as well as the user. Wood doors, steel doors, fiberglass doors and aluminum storm or screen doors each have their own requirements. A lock that fits a wood door may not fit a steel door without adjustment. A thin metal door may need an extra reinforcement, and a glass panel door needs extra care so the lock cannot be reached by breaking the glass.

Check the backset, which is the distance from the edge of the door to the center of the large hole. The two common sizes are standard. A lock must match the existing backset, or the door must be adjusted. Check the door thickness too. Most doors are a standard thickness, but some are thicker or thinner and need an adapter or a different lock.

Handing matters for some hardware, particularly levers and some mortise sets. A lever set is made for a door that swings in one direction or the other. Many are reversible, but not all. A technician will check.

Finish and style matter to many people. Common finishes include brass, nickel, bronze and black. Finishes differ in durability, particularly outdoors in salt air or intense sun. Where you live matters here: coastal climates are hard on some finishes, and a technician familiar with your area can suggest what lasts.

What happens during a lock change visit

A lock change is usually a smooth job when the preparation is right. The technician starts by confirming who you are and that you have the right to authorize the work. They look at the door, the existing hardware and the frame, and talk through what you want. They explain what is needed and flag any problems before starting.

They remove the old lock, then check the holes and the latch recess. If something needs adjusting, they do it, for example enlarging a hole, fitting a plate or chiseling a recess to the right depth. They fit the new lock, align the strike plate and make sure the bolt moves smoothly into the frame. They install long screws where recommended.

Once the lock is in place, they test it. They operate the key and the thumb turn several times with the door open and then closed, check that the bolt extends fully and retracts easily, and check that the latch catches without the door needing to be lifted or pulled. They check the alignment with the door closed by looking at the gap between the door and the frame.

The technician then hands over the keys, explains how the lock works, and tells you about any features such as a key control setup. If you want other locks on the property changed to match, they can cut keys to suit. Quotes are given by phone, and if the job turns out to be complicated, an on-site visit may be needed to assess it, with the service call charge explained before anyone is dispatched.

Checks after installation

A well installed lock should pass a few simple tests. You can do them yourself after the technician leaves, and a good technician will do them with you.

1. With the door open, turn the key and the thumb turn several times. The bolt should extend and retract smoothly without catching.
2. Close the door and engage the deadbolt. It should slide into the strike without the door being lifted, pushed or pulled.
3. Look at the gap between the door and the frame. It should be even along the edge. A large or uneven gap points to a sagging door or a hinge issue.
4. Check the strike plate. It should be firmly fixed with long screws, and sit flush with the frame.
5. Test each key you were given, including the spare keys.
6. Check that the handle or lever returns to its resting position and that the latch catches without sticking.
7. Make sure you can open the door from inside quickly without a key, if it is an exit door.

Matching several doors and managing keys

If you are changing more than one lock, think about how you want the keys arranged. Many people prefer all exterior locks to work with one key, called keyed alike. Others want the front door and back door on one key, and the garage or a separate building on another. A technician can set up the locks in different ways.

Keyed alike sets are convenient but they put all the eggs in one basket. If one key is lost, all the locks are affected. For most households, the convenience outweighs the risk, and a lost key can be dealt with by rekeying. For rental properties, offices or shared buildings, a more structured key plan may be better. Our page on master key systems describes more complex arrangements.

Make sure you receive enough keys. Think about each household member, a spare kept outside the home with someone you trust, and any regular visitors. Do not hide a spare under a mat or in a flower pot. If you want guests to enter without a key, think about a keypad lock.

Keep track of your keys. Mark them or keep a list. Avoid stamping the address on a key. If you lose a key, treat it as a risk and consider rekeying promptly.

Safety and code considerations

A lock must work in an emergency as well as protect against intruders. In a fire, everyone in a house must be able to leave quickly, which is why many homes have thumb turns on interior sides of exit doors, and why double cylinder deadbolts are restricted in some places. Check local building and fire codes, and ask the technician about the rules in your area.

Rental properties, apartments and commercial buildings often have additional rules. Some require that exit doors be openable without a key from the inside at all times. Some require a specific type of hardware on fire rated doors. If you manage such a property, check with the local authority or building manager before changing hardware. Our page on commercial door hardware covers some of these cases.

Do not tamper with fire rated doors yourself. These doors are built to specific standards and altering them can void the rating. Hardware on such doors must be listed for the purpose. A technician can advise on which hardware is suitable.

Finally, think about accessibility. A lever handle is easier to use for people with limited grip than a round knob. Thumb turns should be easy to reach and operate. If someone in your home has mobility issues, mention it when you call and the technician can suggest options.

What to have ready when you call

A few details help the person on the phone work out what you need and how to quote it. Prepare these before you call.

• How many doors and locks are involved, and which doors.
• What you want: new locks, new keys, extra deadbolts, a different style or an upgrade in security.
• The type of each door: wood, steel, fiberglass, glass panel or aluminum.
• The type and condition of the existing locks, and the brand if you can see it.
• Any damage to the door or frame, and whether there was a break-in.
• Whether you are the owner, a tenant or a property manager, and the paperwork to show it.
• The address, access arrangements and when someone will be there.

Next step: a plain conversation by phone

Choosing locks does not need to be complicated. Describe your doors and what you want, and the person on the phone will explain the options. Quotes are given by phone only, and we do not publish prices or ranges online. If the job is complicated, for example a damaged frame or several doors needing preparation, an on-site visit may be needed, and the service call charge is explained before anyone is dispatched.

When you are ready, call. Tell us what you have and what you would like to change, and we will help you decide between rekeying, replacing and upgrading.

Questions people ask

Related pages

Written by Claude (AI) (AI) for 24/7 Locksmith USA.