Door alarms are devices that sound an alarm when a door is opened without disarming the device first. They are commonly used as security measures in homes, businesses, schools and other facilities to alert occupants of unauthorized entry. But are these alarms actually effective at deterring intruders and preventing break-ins? Let’s examine the pros and cons of door alarms and look at some key factors that determine their effectiveness.
Page Contents
- 1 Are door alarms an effective security measure?
- 2 Types of door alarms
- 3 Installing door alarms
- 3.1 Mounting location
- 3.2 Door frame or window molding
- 3.3 Adjustable sensor direction
- 3.4 No background noise interference
- 3.5 Alarm volume
- 3.6 Power source
- 3.7 Backup power source
- 3.8 Tamper resistant
- 3.9 Test functionality Check that the alarm reliably triggers when opening the door and verify it is loud enough. Walk test the range throughout the property. User guide
- 4 Are door alarms suitable for children?
- 5 Door alarm recommendations
- 6 Conclusion
How do door alarms work?
The basic functionality of most door alarms is quite simple. The alarm unit consists of two parts – a sensor that is installed on the door frame and a main alarm unit that is mounted on the wall nearby. When the door is closed, the sensor is lined up with the main unit. Opening the door breaks the connection between the sensor and main unit, which triggers a loud alarm ranging from 80 to 130 decibels.
Some systems may also incorporate features like a control panel, remote controls, motion sensors, phone dialers to call authorities and smartphone connectivity. The alarm may sound for a set duration like 60 seconds or longer, or continue sounding until manually shutoff or the door is closed again. Some alarms have a delay feature that allows authorized personnel a few seconds to enter and disarm the system before the alarm is triggered.
Intended uses of door alarms
Some of the primary intended applications of door alarms include:
- Home security – Warning homeowners about potential intruders entering through doors
- Business security – Deterring robbers from entering shops and offices after hours
- School security – Alerting staff to unauthorized access to classrooms, dorms, labs, etc.
- Medicine cabinet alarms – Discouraging access to medicine by children or unauthorized users
- Refrigerator/freezer alarms – Alerting homeowners if the door is accidentally left open
- Wandering patient alerts – Warning caregivers if dementia patients open exterior doors
- Pool gate alarms – Notifying parents/lifeguards if children enter pool area unattended
- Child proofing – Deterring toddlers/young children from entering rooms unsupervised
Are door alarms an effective security measure?
The effectiveness of any security measure depends on how well it meets its intended purpose. To determine if door alarms are effective, we need to look at some key criteria:
Criteria for an effective door alarm
- Loud audible alert – The alarm must be loud enough to be heard throughout the property in order to alert occupants and scare off intruders.
- Reliability – It must reliably sound each and every time a protected door is opened without disarming.
- Power source – The alarm needs a reliable power source so it keeps working if the electricity goes out.
- Tamper resistance – It must be designed so intruders cannot easily disable or destroy the alarm.
- Easy to arm/disarm – Authorized users should be able to easily shut off the alarm when entering legitimately.
- Difficult to circumvent – Intruders should not be able to bypass the alarm without setting it off.
Do door alarms meet the criteria?
* Loud audible alert – Most quality door alarms are designed to produce an extremely loud sound ranging from 80 to 130+ decibels that can be heard throughout a property. This loud noise is highly effective at alerting occupants of an intrusion and scaring off burglars.
* Reliability – Modern wireless alarms are generally very reliable at sounding when a door is opened if installed properly. However, cheap units may have connectivity issues that prevent them from working consistently.
* Power source – Many alarms plug into an electrical outlet, so will stop working if the power goes out unless they have a battery backup. Battery-powered units will continue working during a power outage.
* Tamper resistance – Tampering is a challenge with any security device. Higher-end alarms have tamper-resistant designs but determined intruders may still be able to disable them.
* Easy to arm/disarm – Most alarms come with remote controls, digital keypads or smartphone disarming making it convenient for authorized users while intruders won’t have the code or device to deactivate it.
* Difficult to circumvent – Experienced burglars may know tricks to get around certain alarms but there are design features to reduce bypass vulnerabilities.
Real-world effectiveness
Studies examining the real-world effectiveness of door alarms have shown they can deter break-ins when used properly:
- A study in the Netherlands found the addition of door alarms reduced burglaries by 26% compared to homes without alarms.
- Research in the U.K. showed houses with alarm systems had a 50% lower chance of being robbed compared to properties without alarms.
- Per a U.S. national crime victimization survey, households with security systems experienced a significantly lower rate of property crime and burglary compared to households without alarms.
However, door alarms are not a foolproof solution. Their effectiveness depends on factors like proper installation, maintenance, power source reliability, tamper resistance, and how occupants respond to alarms. They may deter casual intruders but won’t stop determined burglars who know how to bypass them. Using alarms in conjunction with other security measures like locks, lighting, cameras results in the best protection.
Types of door alarms
There are a variety of door alarm types and models on the market using different features and technology.
Wired vs wireless door alarms
Traditional wired alarms are connected via power cables running to an electrical outlet and wiring between the sensor and alarm unit.
Wireless alarms operate using radio frequency, WiFi or Bluetooth signals to communicate between the sensor and alarm without wires.
Pros of wired alarms:
- Don’t require batteries or charging
- No signal interference issues
- Harder to jam/block wireless signal
Pros of wireless alarms:
- More flexible installation without running wires
- Portable, temporary use
- Easy to expand system with additional sensors
- Some have WiFi connectivity features
Power source
Door alarms are powered either by:
- AC power – Plug into electrical outlet
- Batteries – Typically 3V or 4V batteries like CR123A, CR2, AAA, etc.
- Hardwired – Connected to a burglar alarm system’s backup battery
Battery-powered or hardwired alarms continue working during a power outage. Battery alarms are portable but require routine battery replacement.
Alarm sounds
Door alarms produce various sounds when triggered:
- High volume siren – Loud siren alarms, typically 90 – 130 dB range
- Chime – Pleasant doorbell/chime sound, lower 65 – 80 dB volume
- Squeal – High pitched alarm squeal, 80 – 100 dB
- Voice warnings – Recorded voice messages
The extremely loud siren alarms work best for security purposes. Softer chimes and voices are used for non-security alarms.
Smart connectivity features
Some modern digital door alarms offer smart connectivity and remote control through smartphones, tablets and smart home hubs. This allows users to:
- Arm/disarm from anywhere
- Monitor alarm status
- Get mobile alerts if alarm triggers
- Integrate with smart home automation systems
Smart alarms increase convenience and expand monitoring/control options beyond just at the alarm itself.
Additional sensors
Many door alarm systems support adding extra sensors such as:
- Motion sensors – Detects movement and triggers alarm
- Glass break sensors – Listens for glass breaking and alarms
- Smoke/fire sensors – Triggers alarm in case of fire
- Flood sensors – Alarms if water leak/flooding detected
- Door/window contacts – Detects opening of doors/windows
These sensors enhance security by triggering the alarm in response to other intrusion detection events beyond just the door opening.
Alarm duration
Door alarms are adjustable to sound for different durations when triggered:
- Momentary alarm – Sounds for 5 to 30 seconds
- Continuous alarm – Sounds continuously until turned off manually
- Automatic shutoff – Shuts off automatically after 1 to 3 minutes
A short alarm works well for notifying homeowners of activity while continuous alarms are more appropriate for security applications to scare away intruders.
Entry delay
Security alarms often have an entry delay feature that gives legitimate users a grace period to enter the premises and disarm the system before the alarm sounds. Entry delays are commonly 20 to 60 seconds but programmable. This prevents false alarms when authorized people enter through protected doors.
Installing door alarms
Proper installation is key to making sure your door alarm works reliably. Here are some best practices:
Mounting location
For hinged doors, the alarm sensor unit is typically mounted on the door frame while the main alarm unit goes on the wall across from it. The door should separate the two units when closed.
On sliding doors, the sensor can attach to the moving door while the alarm unit mounts on an adjacent wall.
Make sure objects don’t obstruct the sensor’s line of sight to the main unit. Mounting them high up helps avoid potential blockages.
Door frame or window molding
If mounting on a door frame or window molding, make sure it is solid wood or metal construction. Plastic, vinyl or hollow frames can reduce the effectiveness and sound level.
Adjustable sensor direction
Look for a sensor that pivots so you can angle it properly to point at the main alarm unit when the door is closed.
No background noise interference
Avoid mounting the alarm system near sources of loud noise like televisions, radios or air conditioning units as this can prevent occupants from hearing it.
Alarm volume
Mount the main alarm unit in an area where the sound can propagate throughout the property, not in a closed room or crowded corner.
Power source
If using a battery-powered alarm, install fresh name-brand batteries like Duracell or Energizer for longest life. Check batteries every 1-2 months.
Backup power source
For AC-powered alarms, consider a backup battery or hardwired connection to provide power if electricity goes out.
Tamper resistant
Secure the alarm system using tamper-proof screws or hidden fasteners. Use tamper seal stickers which reveal tampering.