Your staff keep propping the back door. Someone put a beeping alarm on it, or you are about to buy one. Before you spend more, it helps to know what a door held open alarm for a business can and cannot do, when your access control already covers the door, and when you need an alert that reaches a person who is not standing there.
This guide compares the options in plain terms. It ends with tests you can run on your own doors with any vendor, including us.
Why business doors get propped
Before you choose any alarm, find out why each door gets propped. Common reasons include:
- A delivery that takes several trips.
- Trash, recycling or cardboard runs.
- Breaks outside.
- Heat or airflow in a kitchen, stockroom or workshop.
- Contractors or cleaners moving equipment in and out.
- A staff member without a key or badge who does not want to be locked out.
The reason matters because it tells you what a fix has to allow. A door that sees deliveries every morning needs a different rule from a side exit that should rarely open.
While a door stands open, anyone can walk in, stock can walk out, and the heating or cooling you pay for leaks outside.
What a local door prop alarm does
A local door prop alarm is mounted on the door or on the wall beside it. When the door stays open longer than a delay set at installation, it sounds.
Models differ, so read the product sheet. Two examples:
- A battery unit. The Detex EAX-300 is a battery powered door propped alarm. Its catalog sheet says door open times from 1 second to 4 minutes are field selectable. It also says the alarm silences when the door is closed.
- A unit that can report elsewhere. The SDC EA Series may be used as a standalone device or integrated with an access control system. Besides its local light and sound, it includes a built-in alarm relay for remote monitoring.
A local alarm is loud where the problem is.
Its sound reaches only the people who can hear it. If the alarm is wired to another system through a relay, that other system decides who finds out. Ask what it would report to, and who watches that system.
When a local alarm is not enough
A local alarm is enough when someone who can act on it hears it every time. Check each propped door against these conditions. If any is true, the beep alone is not enough.
- Nobody is in earshot. The door is at the far end of a warehouse, behind a noisy kitchen, or on a floor where people wear hearing protection.
- The building is empty. After closing, a door left open sounds to nobody.
- Nobody owns the response. If everyone hears it and everyone assumes someone else will go, or staff have learned to work through the noise, the alarm has stopped doing its job.
- You need to know what happened. If you want to know how often a door was propped, for how long and on which shift, an alarm that keeps no record cannot tell you.
- You have more doors than people. One manager cannot walk to every door that is sounding.
Four ways to know a door is open
- A local prop alarm. Good at sound at the door. Leaves open anyone out of earshot, and any record of what happened.
- A local alarm that reports to another system. Good at local sound plus a signal, through a relay, to an access control panel or another monitoring system. Leaves open everything that depends on what it reports to and who watches that.
- Access control held-open alerts. Good at doors that already have a reader and a door position sensor, with alerts sent to named people. Leaves open any door without a position sensor, such as a back door that never got a reader.
- Wireless door sensors that alert named people. Good at covering doors that have nothing today, with a rule for each door and alerts to the people you pick. Leaves open the questions in the test list below, which differ by product.
Doesn't our access control already do this?
It might. Access control can alert when a door is held open, as long as the door reports its position.
Verkada's help documentation, for example, says its door opened, held open, forced open and tailgating alerts only trigger if a door position indicator is installed. The same documentation says the held-open alert is enabled in installer settings, where you can set how long the door must be held open before an alert is sent. It also says these alerts generate around the clock by default, and you specify the days and times they send notifications.
So the practical question is which of your doors have a position sensor and an alert set up. A door without a position sensor cannot trigger those alerts. For the full side by side, see our door monitoring vs access control comparison.
Back doors and dock doors: what to verify
Back and service doors are usually hinged doors that people walk through. A loading dock may have an overhead or roll-up door, a hinged door beside it, or both. A sensor made for one kind of door may not suit the other.
Before you buy:
- List every back and dock door you care about, with its type.
- Ask each vendor, in writing, which of those door types its sensor is made for.
- Ask to see it working on your own dock door, not on a demonstration door.
- Ask how deliveries are handled: whether a dock door can have a longer limit or a quiet window, who can set it, and whether monitoring comes back by itself afterwards.
- Decide who should hear about a dock door left open at night.
Treat dock door support as something to confirm for the product in front of you, ours included.
Test before you buy
A demonstration on a showroom door tells you little about your building. Run these tests on a real door at your site, with the vendor present or on a trial unit, and write down what happens. They are tests for you to run; this guide does not report results from running them on any product.
- Walk through normally, several times. Does anything alert when it should not?
- Leave the door open past its limit. Who receives the alert, how long does it take, and what does it say?
- Do nothing after the alert. Does it repeat, or go to someone else? Can the person alerted show they are handling it, and is that recorded?
- Close the door. Is anyone told, and is the close logged?
- Run a real delivery. Can the door stay quiet for the delivery without anyone switching the system off? Who can do that, and does monitoring resume by itself?
- Change a rule. How long does it take to change a door's limit or who gets alerted, and who is allowed to?
- Take the battery out of a sensor, or cover it. Does anyone find out, and how?
- Unplug the receiver or base station, or cut its internet or cellular connection. Does anyone find out, and do events from the outage arrive later?
- Ask for the log afterwards. Can you export what happened by door and by time?
- After a week of normal use, count the alerts staff ignored.
Then ask, in writing: what does it cost per door and per building, at the start and every year after? Who supports it after hours? Who owns the event data?
What door monitoring does not do
- A door sensor tells you whether a door is open or closed. It does not tell you the door is latched or locked, so keep checking the door hardware.
- Monitoring is not a lock. It tells you about a problem, and someone still has to close the door.
- It does not settle fire or egress questions. Before you add any alarm or hardware to an exit door, check with your local fire authority and your door hardware supplier.
Where Positive Proof fits
Positive Proof's door monitoring puts a wireless sensor on the door and sends alerts to the people you choose. Every Positive Proof door proposal so far is a school document, so the capabilities below are documented for schools. Positive Proof has also confirmed an offer of door monitoring to a business.
As those proposals document it:
- Each door gets its own sensor, with no wiring and no power run.
- There is nothing for staff to arm, disarm or carry.
- Each door has its own time limit, so a door that sees deliveries can have a longer one.
- Rules change by time of day and by calendar day, door by door.
- A door can alert when it opens, or only when it stays open too long.
- One door can reach one group and another door a different group, and the same door can reach a different group at night.
- An optional sounder goes off right where the door is propped, alongside the alert, so you can keep a local alarm where it helps.
- Every open, close and propped door is logged with time and location, ready to download.
- Every alert carries a delivery record, so you can see it landed and when.
- Card readers cover the controlled doors, and sensors cover the other doors in the building.
Bring the test list to a demonstration, on your own back or dock door, and judge us by what you see. Request a demonstration.
Frequently asked questions
What is a door prop alarm?
A door prop alarm sounds when a door stays open longer than a set delay. Some are battery units that sound at the door. Others also have a relay output that can report to another system, such as access control.
How can I get notified when a door is left open?
You need something that reports beyond the door: a local alarm wired through a relay to a system someone watches, an access control held-open alert on a door with a position sensor, or wireless door sensors that send alerts to the people you choose. Test who actually receives the alert before you buy.
How do I stop employees from propping doors open?
Start with why each door gets propped, and fix what you can, such as a delivery routine or a door that is hard to keep shut. Then put an alert on the doors that still get propped, and make one person responsible for responding to each door's alert.
Is a local door alarm enough for a business back door?
It is enough if someone who can act will hear it every time the door is propped. It is not enough when the door is out of earshot, when the building is empty after hours, when nobody owns the response, or when you need a record of how often the door was propped.
Can a door held open alarm work on a dock door?
It depends on the product and the door. Overhead and roll-up dock doors are a different kind of door from hinged back doors. Ask the vendor in writing which door types its sensor is made for, and test it on your own dock door before you buy.
