After the doors, your windows are the weakest link in your home security net. In order to truly protect your family and valuables from burglars, you should have a system in place that can notify you of any attempt to gain access to your home through your windows. Window alarms are designed to meet this need. These devices are generally compact, simple to install, and effective at providing you with an additional level of security in addition to added peace of mind.

If you’re unsure where to start your search for window alarms, we can help. We’ve created this guide to introduce you to some of the features and other factors you’ll need to consider when buying and installing window alarms in your home. We also let you know how much you should expect to pay and offer some recommendations for window alarms that we particularly like.

While there are variations from model to model, most window alarms of this nature have two parts: an alarm box and a sensor. The alarm and sensor are installed on the window frame and casing in close proximity to each other so they can establish a link of some sort (usually a magnetic field). When the window is opened, this breaks the field and sets off the alarm.

Window alarms are typically constructed from plastic, and any alarms you buy should be both durable and compact. Choose ones you can live with in terms of appearance because there isn’t a whole lot of variety here when it comes to design. You’re largely going to be stuck with white for the color, but you do have some options in terms of shape (round, rectangular) and accent colors or patterns.

As long as you mount the box and sensor close enough to each other that they create a field, the installation of these alarms is pretty simple. However, mounting can sometimes be a weak point, particularly if the alarms use simple double-sided tape to hold the alarm box and sensor on the window and sill. If the tape fails on either the box or the sensor, it will fall off the window, set off the alarm, and needlessly scare you and your family.

Read the online comments by users of the alarm you’re considering. If they suggest problems with the tape or mounting, consider purchasing some stronger double-sided tape, devise a sturdier mounting method, or search for a different model.

All window alarms of this kind run off batteries of some sort. Know what type of batteries the alarm box and sensor use in addition to what type any accompanying remote uses. Be sure that the batteries are readily available. Batteries such as AA and AAA will be easy to find, but some alarms use batteries that could be more problematic to source. Also check whether the alarm you’re considering ships with the batteries (this is pretty standard).

Low battery alert: Do you have an easy way to check the battery level? Any window alarm you buy should either alert you when the battery is running low (through regular beeping) or have a button that enables you to check the battery level.

Because you’ll probably be mounting alarms on more than one window, it helps to know the number of units that ship with each order. You can find these alarms sold singly or as sets of two up to as many as a dozen. Know the number of windows you’ll be securing as you compare alarms.

While not standard, some window alarms ship with a remote control. A remote provides you with an easy way to arm and disarm the alarm even when you’re outside the house. You can also use the remote to test the alarm’s battery level, and some remotes feature an SOS or panic button that you can use to alert others in the house to a potential problem.

If your window alarm ships with a remote, be sure that you also have some way to arm and disarm the alarm on the unit itself. If not, purchase additional remotes to use as backups in case you break or lose the original.

Window alarms have various modes. Learn the modes on your alarm and how easy it is to switch between them, either as a readily available switch on the alarm box or via the remote. Try to avoid any model that requires you to take apart the box to change the mode. Alarm modes include the following:

Off: You should be able to turn any alarm off so you can open a window without setting off the alarm.

Alarm mode: This the heart of the unit. Set it so that any time the window is opened, an alarm will sound.

Chime: When set to Chime mode, opening a window will trigger a gentle – usually single – tone. This is handy when you just need to be notified that a window has been opened, such as by a child, and not be shocked into calling 911.

Is the alarm loud enough for your purposes? These window alarms generally run in the range of 100 to 130 decibels. The higher the decibels, the likelier it is that you’ll hear it going off from any room in your house. Also note the loudness of the Chime mode (if the alarm has one), and how much noise it emits when you arm or disarm the alarm. It’s helpful if you can adjust the volume for any or all of these modes or tasks and set it to your own preferences.

Window alarm sets start at less than $10 and can run up to $30 or more. Much of the difference in price depends on the number of units per set. Check whether you’re buying one alarm or eight and you can figure out how much you’re paying per alarm. Sets that include any additional items, such as a remote, cost a bit more. And if your alarm doesn’t ship with batteries, figure those into the initial cost as well. Finally, know what type of a warranty, if any, the manufacturer provides with the alarms because this can vary considerably from model to model.

• Install window alarms of this kind inside only. They aren’t built to handle the weather, and potential burglars could easily deactivate the alarms if they have access to them.
• Use screws instead of tape for mounting if you can. If your window alarms use tape for mounting, check whether you can use your own screws in place of the tape. You might need to drill some holes, but the mount will be much stronger and lessen the possibility that the alarm or sensor will fall off.
• Check the tape periodically. If you install a window alarm unit with double-sided tape, check it periodically to verify that the tape is still holding securely.
• Sync your window alarms with an existing system. If you have an existing security system, consider paying more for alarms that can sync up with the system and alert a security company in the event of a breach.
• Pay close attention to the mounting instructions. These alarms all have specific and varying placement recommendations in terms of the distance between the alarm box and the sensor.

In addition to the window alarms we spotlight above, we wanted to mention a few more that caught our eye. The EVA LOGIK Security Window Alarm can detect vibrations and is available in sets of two or four. It has a 120 dB alarm and also features blinking LEDs and warning stickers to help deter potential burglars. The Noopel Door and Window Alarm comes in a pack of two and offers a simple on/off mode and an ultra-thin design. And if you like your alarms loud, check out the LACORAMO Door and Window Alarm, which sounds at 130 decibels. This option also includes two remotes and an SOS button.

Q. How secure are these window alarms?
A. These alarms are effective at notifying you when someone is trying to enter through a window. Since they only alert you when the window frame moves, however, they won’t sound if someone is able to break enough glass in the window to enter without moving the frame itself. Consider pairing these alarms with motion sensors to completely secure a window.

Q. Will the alarm on these continue to go off after the window is closed again?
A. Not usually. While this varies from model to model, the way these alarms typically work is that the alarm only sounds when the magnetic field is broken. Once the alarm unit and the sensor are realigned (for example, by shutting the window), the field is reestablished and the alarm stops.

Q. Will these alarms work on sliding doors in addition to windows?
A. So long as you can mount both the alarm box and sensor in such a way that they line up correctly (for example, with the alarm box on the door frame and the sensor on the sliding door), you should be able to use them in this way. You should check with the manufacturer to verify this, however.