Do I need Window Sensors if I have Motion Detectors?

I just purchased a full complement of open/close window sensors from SmartThings. I also got 4 Ecolink motion sensors. On top of that, I have 1-2 webcams that I’m setting up, and a SmartSense Multi on every door. My friend suggests that the window sensors are overkill, as the motion sensors will detect any issues.

Do I need Window Sensors if I have Motion Detectors and the Multi? Thoughts?

Stop the theif before they enter the home IMO. Once they are in the damage is done. Keep the snesors. use them. feel safe.

There’s a subtle difference. Door/windows sensor is a “perimeter security” device while motion sensor is an “area security” device. You can deploy either one or both, depending on your needs.

It also depends on your use. If you’re purely security focused, the window sensors might be overkill.

But if you also want to do some automatic climate control (turn off AC when the windows are open?), they’re the only tool for the job.

I am personally a fan of overkill :wink:

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If you have large dogs, then it may be impossible to prevent them from setting the motion sensors off depending on the layout of the room. In that case, door and window sensors would be needed.

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My feelings exactly. I use the open/close sensors for a number of things that aren’t security related:

There’s an app that will let you know if you have windows open when there’s rain headed for you. I run a app that alerts me if I leave my garage doors open too long. I also have an app that opens my garage door when I get home, then automatically closes it after I open/close my side door.

These are things that can’t be done with motion sensors.

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Yep. And i like to run the “knock app” to turn on lights should someone knock on my door at night and im not home.


Wondering what other thoughts are…

@jterpslaw Of course you can also use motion sensors to turn lights(and other things) on and off as you move about the house.

From a security perspective, it’s never good to rely solely on one sensor, or even one type of sensor to provide protection. Window sensors can be bypassed by using a strong magnet to trick them into registering the contact as still closed. Much harder to fool motion sensors unless you are willing to attempt Mission Impossible hijinks.

As you are reading through the forums, you will notice lots of different ideas on how to use the ST ecosystem and to personalize and customize it to match your needs. You may start out looking for a security only type of system, but then start adding convenience functions such as lights and other home automation functions.

With that being said I would say this, start by deciding what you want the system to do for you right now and buying the appropriate hardware to accomplish that goal. If you have budgetary constraints, there are always compromises that can be made.

For example I have ST Multis on all of my doors and windows that are regularly opened. I skipped putting them on several windows that are less accessible from the outside and are in the coverage areas of my motion sensors. Instead I spent the money saved on some ST Arduino shields and to automate my garage door.


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