Window Lock Types Explained

You’ve seen this scene on television and in movies: an intruder crawls through an unlocked or easy-to-open window to steal objects or cause harm to occupants. You may even know people who have been victims themselves. Security is one of the most important aspects of any home. While automated security systems can go a long way toward protecting your family, starting with the basics can help ensure that your home is safe and secure from intruders. There are several types of window locks available to choose from when considering security options for your home.

Keyed Locks

This type of lock requires a key to open or close the window. It’s mounted on the window frame or sash and works well with single hung, double hung and sliding windows. Just remember to keep track of the key if you opt for this type of window lock.

Window Latches

window latch lockYou’re likely familiar with window latches. They are located on the top of the window sash and latch the two parts of a window together when the window is closed. These work with single and double hung windows. You simply turn the handle on the latch to lock or unlock the window.

Sliding Window Locks

These locks are placed in the track of a sliding window to prevent it from opening. This type of lock can use a lever or a thumbscrew. If the sliding window lock uses a lever, you turn the lever to lock and unlock the window. If it uses a thumbscrew, you have to twist a wing nut to secure the lock and prevent the window from opening. Some sliding window locks even use keys.

Ventilating Locks

A ventilating lock is installed above the sash on the window frame. It has a moveable pin that when placed above the window, prevents it from opening all the way. If the pin is pushed aside the window can open fully.

Hinged Wedge Locks

A hinged wedge lock prevents a double hung window from opening. If installed directly above the sash, it can keep a closed window from opening until you push the lock inward to allow the window to open fully. If placed higher on the window frame, the window can be opened partially but without the ability to open it further unless the lock is pushed inward.

Folding Latches

These latches can be used to lock awning and casement windows. You install them on the window frame and fold the lock down to keep the window closed. You only need to pull the latch up to unfold it and allow your window to open.

Lock Pins

A locking pin goes through one sash of a double hung window and into the second sash to keep an intruder from opening the window. The pin is often attached to the window frame with a chain.

Lag Screws

A cheap option for double hung windows are lag screws. You can drill holes on the left and right of the window sash and the insert the screws with recessed washers. You can tighten the screws with a special key. This option allows you to lock the windows when partially opened.

Swivel Action Locks

These locks use a self-locking snib (catch) to prevent a closed window from opening. It does not require a key and work well with most double hung windows. To open a window with a swivel action lock, you turn the snib from left to right to release it.

Window Opening Control Devices

This option is great for keeping children safe. Window opening control devices (WOCD) limit how far a window can open, ensuring that the window doesn’t open far enough to allow a child to climb through the window and potentially fall. A WOCD should only allow the window to open up to 4 inches. There are options for casement, single hung, double hung and horizontal sliding windows.

Make sure that any window opening control device you are buying meets the ASTM F2090-10 standard, a code meant to prevent children under five years old from falling out of a window. These WOCDs require two independent actions to disengage, preventing accidental release. If you do disengage the WOCD to open the window fully, you don’t have to worry about reengaging it. The WOCD will engage again once you close the window. If you are looking for an aftermarket WOCD, make sure it meets the standard and have it installed correctly.

Some parents may think that screens will prevent a child from falling, but the purpose of these screens is to keep insects out and provide ventilation, not protect against a fall. A WOCD is one of the best ways to keep small children safe from fall accidents.

Smart Locks

smart lock

Smart locks are electronic locks that do not require a key to operate. Instead, you can open smart locks with a code or with your smartphone. This technology allows you to share the code with friends, family or anyone else who needs access to your home. While you will most often find smart locks on front and back doors, sensors exist for windows. Sensors can tell you if your window is locked or unlocked, closed or open, allowing you to monitor the safety of your home.

Lock Grades

Now that you know the different lock types, it’s important to understand differences in quality. The Builders Hardware Manufacturers Association has an American National Standards Institute-certified grading system to help you determine the strength of a lock.

  • Grade 1 – The highest grade is reserved for locks with the highest level of security. They are the safest, but also the most expensive.
  • Grade 2 – These locks provide an intermediate level of security and are common for home security.
  • Grade 3 – The final grade is an indication of basic security. You can use these locks alongside a stronger lock. They are also the cheapest option.

Ask a dealer about lock options when purchasing new windows. Keep in mind that purchasing aftermarket locks comes with the risk of choosing the incorrect lock for your window type or incorrect installation. Consult a professional when purchasing aftermarket locks so that you properly protect your home and family.

More Information on Windows

If you’re interested in learning more about windows, doors and other types of glass, check out the Info Center. Are you looking to buy new windows? can help connect you to local window and door dealers.


© 2019 Inc. All Rights Reserved. No reproduction without expressed written permission. Questions? Contact attempts to provide accurate information but cannot be held liable for any information provided or omitted.  You should always work with a licensed, insured and reputable glass shop that can assess your specific needs and local building codes and offer professional services. Never attempt to cut, install, or otherwise work with glass yourself. All content is provided on an informational basis only.

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