Credit: Tim Brookes / How-To Geek

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Tim has been covering technology for almost 20 years, in that time spanning a broad range of topics from security to product reviews. He is especially focused on the Apple ecosystem, productivity, and consumer advice.

Over the years Tim has written thousands of articles, reviews, and round-ups in addition to producing video content and original photography. A graduate of journalism, he found his footing as a freelancer with a laptop and loves how he is able to work from practically anywhere.

Now a Senior Editor for iPhone, Mac, and Smart Home at How-To Geek, Tim still loves to write. He can also be found crafting round-ups and productivity posts for the Zapier blog.

Earlier in his career Tim spent nearly a decade as a writer and eventually Apple section editor for MakeUseOf.

Tim currently lives in Brisbane, Australia. Outside of work he loves to hike and work out, play video games, and spend quality time with his wonderful partner and two cats Inka and Roger.

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I woke up on Sunday morning to find that I’d left the garage door open all night long and that a bike had been stolen. After wishing great harm on whoever decided to take my partner’s daily ride to work, I started thinking about how I can prevent this happening in future with the help of Home Assistant.

Don’t leave the garage door open next time

The obvious point to make here is that leaving the garage door open presented an opportunity that someone couldn’t resist, and closing the garage door would have prevented it. While most of us manage to walk past other people’s property on a daily basis without deciding we’ll take it for ourselves, not everyone is graced with that kind of decency (you can tell I’m not salty about this at all).

Cameras, preferably of the Power-over-Ethernet variety are on my “early 2026” to-do list, but they also probably wouldn’t help in this instance. I already toured the neighborhood looking for back alleys and dumping spots in which the bike could have been temporarily stashed, to no avail. Nothing has showed up on Facebook Marketplace either, so I’m starting to accept that it’s gone.

Weirdly, I already have everything I need to build an automation that could have prevented the theft, but like so many smart home (and specifically Home Assistant) projects, it’s necessity that breeds invention. So that’s exactly what I’m going to do, and it starts with a simple window or door sensor.

Door sensors and a conditional reminder

A few months ago, before I struggled adding smarts to my new garage door opener, I added a simple IKEA Parasoll door or window sensor to my garage door. The garage is underneath the house, with a big tilt door, and the sensor uses a simple magnet design to detect whether it’s open or closed. When the magnetic field is interrupted, and the two elements move apart, the door is reported as being open.

These sensors use a single AAA battery, and I’ve not had any of them fail on me yet. After installing the garage door sensor, I confess that I forgot about it outside of the few instances I manually checked whether I’d closed the door or not after leaving the house. I do the same with a window in the bathroom that I often forget to close, and it’s been a real handy upgrade.

But now it’s time to put that sensor to better use. Though I have got a smart garage door opener with the help of a Ratdgo32 add-on controller, I still feel like I can’t fully trust it after a rocky start. The IKEA sensors, on the other hand? Rock solid. You could get the same results with a sensor from other Home Assistant-friendly manufacturers like Aqara.

So what does the automation look like? I’ve set a trigger for 9 pm every day of the week. I’ve added a condition that the “Garage door” sensor is open to the “And if” field, and then I’ve chosen the “Send a notification via mobile_app_your_name” action to send me a message. I’ve turned this into an iPhone critical alert by adding a few lines of code to the data field too.

So now Home Assistant will check, every night at 9 pm, if the garage door is open. If it’s closed, nothing will happen. If it’s open, my iPhone will angrily remind me to close it. Job done.

This is just a starting point

This conditional automation is a good example of why Home Assistant’s automations are so much better than simpler platforms like Apple Home. The ability to create conditional automations that only perform actions if a certain criterion is met gives a smart home so much more potential.

Another idea I had was to create a simple indicator that the garage door is open. The plan is to buy or build a small light that comes on whenever the garage door is open. You can do this by using the state of the door sensor as the trigger, with the action being to turn on a light. You can then create another automation to turn it off, and get creative with colors or flashing patterns.

Credit: Bertel King / How-To Geek

You could get even more complex with this, for example, if there’s a camera facing your garage, you might be able to train whatever software you’re using to identify what an open garage door looks like (or maybe use your car’s visible license plate). You could then use that as a trigger instead, and you’d never need to bother with a battery-powered sensor.

The point is you’ve got options, and it’s always best to know what they are and how to implement them before an event like a theft or a break-in occurs.

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The best time to have this automation up and running would have been the day I installed that garage door sensor. The second best time is now. Looking for more Home Automation security tips? Check out how to build a makeshift Home Assistant alarm system.