Door sensors and window sensors: Overview

This is a guide to door contact access control and using contact sensors to trigger alarms when doors or windows are opened without authorization.

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What are door sensor alarms?

In door contact access control systems, sensors play a crucial role in detecting the status of a door, such as whether it is open or closed.

Door and window sensor alarms are actually the same device. The basic functioning is a contact sensor that triggers an alarm when a door or a window is opened without authorization. This type of alarm represents the ultimate perimeter defense for your facility and it is widely used in commercial and residential buildings.

Before diving into the types of alarms, let's take a look at how these sensors work.

How do door sensors work?

Door and window sensors are contact sensors composed of two main parts that are a magnet and a sensor. This is also called a magnetic switch. The magnet itself is generally placed on the door, while the sensor is installed on the door frame. The alarm is triggered when the door or window is opened without authorization (door-open alarm) or when the door is forced open (door-forced-open alarm).

There is a third type of alarm that is triggered when glass is broken, but as the functioning is slightly different, we have a separate Glass Break Sensor Overview resource dedicated to this type.

Types of door sensors alarms

Door-open alarms

Door-open alarms activate when a door is opened by an intruder and held open for a certain period of time. The door-held-open time is programmable and used to monitor if a door is opened by an authorized access requestor. The door alarm warns the owner by emitting a chime, a loud siren sound or a flashing light, or both.

Door-open alarms are also called door-left-open alarms or door-held-open alarms. Door alarms of this type are made of two components: a magnetic stripe fixed on the door panel and an input sensor fixed at the door frame. When the contact between the magnet and the sensor is interrupted, the door alarm generates a warning signal.

Door-forced-open alarms

Door-forced-open alarms activate when a door is opened by force, activating the switch contact.

An example of forced behavior is trying to get through a door without using a valid access card. Instead, the intruder uses physical force to get the door open.

All types of door alarms can be used for combination in comprehensive door alarm systems.

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How do door sensors serve your security needs?

Door sensors serve to create safe spaces by warning against intrusion at access points that get opened often. The sensors in door contact access control systems are essential for monitoring the status of doors and ensuring the security of a controlled area. They provide real-time information to the access control system, allowing it to enforce access policies effectively and respond to any unauthorized access attempts or breaches. They can work equally well with doors, windows, and cabinets.

A door-held-open alarm with a pleasant chime can warn a receptionist that a visitor has just entered the building, leaving enough room for attending other duties. When an intruder tries to forcefully break through an office door that he or she is not authorized to use, the monitoring system will let the controller know. Door-left-open alarms enable setting longer delivery times for goods and reducing them when the delivery is complete. They guard against one of the most common security intrusion events - piggybacking or tailgating.

Door alarms are effective burglary protectors. The moment a door is opened by a burglary attempt, the sensors can activate a flashlight, a loud siren, and a phone call, or any combination of the above. The phone call system can be connected to the owner’s phone, to a private security contractor, or to a law enforcement agency. These safeguards can reinforce your peace of mind when installed properly, ensuring you are always kept informed of security breaches and events.

A look into wireless door alarms

Most advanced custom door alarms on the market use wireless technology and are, therefore, incredibly easy to install and use. They can be combined and integrated into a comprehensive alarm system with motion sensors, security cameras, and access control.

Since they are more sensitive and smaller than conventional alarms, wireless door alarms provide stronger, undetectable, and reliable protection for difficult-to-reach spots. They can be set independently or fit within an existing wired alarm system. Backup power supplies prevent system fallouts in the event of electricity cuts.

The wireless door alarm models are usually offered in sets of several elements that can be customized with add-ons.

Do I need a window sensor on every window?

When looking to install this setup, many people ask whether there is a need to install a sensor on every window. Window sensors are meant to trigger alarms when a window is opened or forced. This means that there is no reason for installing window sensors on windows that cannot be opened or forced, such as those located on higher floors.

Which windows are set up with an alarm trigger is a decision that your team is best equipped to make, with the knowledge of your own premises. It is not necessary that all windows are covered, but our suggestion would be to be protected as much as possible by enabling the alarm on all the accessible windows.

Door sensors manufacturers in door contact access control

Another important factor to consider when purchasing a door or window sensor is the brand. The options on the market are countless, and the technical specs often create confusion instead of providing more clarity.

For this reason, we have decided to briefly look through the most-searched-for door sensor manufacturers to help you with your choice.

Nest door sensors

Nest is a great place to start, as it is one of the most famous brands when it comes to security. Google, which owns the brand, invested in both innovation and great design, making it a great security system that looks amazing.

There are really only a few downsides to this solution. The biggest critique of Nest is the price tag. This solution can be set up as standalone hardware, or can be purchased with a 36-month contract, but these two versions of the solution have one thing in common: they are a bit more expensive than the market average. This, however, should only be a concern if you are purchasing this for your home. The price tag does not change if you are a private or a business, and the solution is pretty in line, if not cheaper than, other commercial systems.

With regards to the pros, Nest did something that nobody had ever done before: merging door and window sensors with motion sensors. This means one single device takes care of the whole security of a room. The sensors also integrate beautifully with the rest of the Nest hardware, to create a great security system overall.

As we see in our guide for the best commercial security systems, Nest is the best solution if you have a small business. Check out the guide for a better overview of the security systems landscape.

Hive door sensors

Hive door sensors stand apart from the solutions described here so far. Their sensors are extremely customizable and can basically be set up to do whatever action you want. You can trigger light bulbs turning on when a door is open, or activate alerts if you're leaving your front door without having shut all the windows.

Generally, even if not extremely cheap, we see Hive as a solution that is less optimal for businesses, because security is not the main point with Hive door sensors. The goal is more accurately described as to create a smart home environment where you can be creative and customize your home however you want. Businesses, in general, tend to worry more about having a reliable security system that is easy to install and quickly grants the best security for employees and company property.

This brings us to the second criticism of Hive's sensors: the setup. The setup with these sensors tends to take a bit longer, as you can really trigger any type of action you can think of. Many private customers lack the necessary knowledge to install these in a short amount of time, but once the solution is set up, then you will be able to have your ideal smart home system.

Ring door sensors

Ring is also a company that pops up frequently when talking about security systems. Their solution is one of the cheapest on the market, and this aspect makes it very widespread in the world of home security. Their door and window sensors are a great option for securing your facility without compromising your budget: the setup is easy and the solution works very well once it is installed.

If you are a business, we would still recommend looking into other options that better integrate with cameras or access control. Moreover, it’s important for businesses to have a solution which can accommodate granting access and securing spaces at scale. A great place to start the research is our guide for the best commercial security systems.

Kisi wireless contact sensor

If you're looking for a complete platform that covers everything from access control to management and security, Kisi is your solution.

Kisi also makes easy-to-install wireless contact sensors that can be attached to your door or window without any tools, and run completely wirelessly on a battery graded to last more than five years. Because they are a first-party contact sensor, they quickly connect to the Kisi access control system and begin working with your existing Kisi products.


In conclusion, finding the best door sensors for intrusion detection and monitoring security events can be overwhelming with so many solutions on the market, but hopefully, this guide has helped to clarify some points to consider when looking for a system that best suits your needs. If you want to know more about the best brands for door sensors, check out our extensive guide.

Door and window sensors in access control

Access control businesses often work with door and window sensors to grant an additional level of security. Door and window sensors can be connected to an access control system in order to use the same dashboard for both and to convert the alarm signals into notifications for the business owner or admin.

If you are interested in learning more about intrusion alarms, feel free to check out our overview page or download our guide to intrusion detection.

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