Basic Questions About Monitoring Apps
Is there an app that can tell me if my foundation crack is serious?
No. Not reliably. Some apps claim to analyze photos of cracks and assess severity, but foundation assessment depends on context that a photo can't capture. The type of foundation, the soil conditions, the crack location relative to structural elements, whether the crack is active or dormant, the local climate. A photo shows you a line in concrete. That's it.
My cousin in California downloaded an app that told him his crack was "low risk." A structural engineer later told him it was earthquake damage that needed $4,200 in repairs. The app was comparing his crack to a database of images. It had no idea his house had been through a 4.1 magnitude quake three months earlier.
Use apps for documentation. Use your brain (and sometimes a professional) for assessment.
What's the most useful digital tool for monitoring cracks?
Your phone camera. Hands down. It's not glamorous, but consistent photo documentation over time is the most valuable thing you can do with technology. Take the same photo from the same angle with a ruler in frame every time you check a crack. Store them in dated folders. Compare them side by side months or years later.
I've been doing this for over a decade. Looking at a crack photo from 2014 next to one from 2026 tells me more than any app ever could. The crack hasn't changed. That's the data that matters.
Are there apps specifically designed for foundation crack monitoring?
A few exist. Most are designed for construction professionals rather than homeowners. Apps like Onsite and similar inspection tools let you log crack locations, take annotated photos, and track changes over time. Some are free, some charge monthly fees.
For the average homeowner monitoring a few cracks, these are overkill. A notes app with photos works just as well. I use a simple folder system on my phone and a paper notebook as backup. Rick once said the best monitoring system is the one you'll actually use consistently, and for most people that's the simplest option available.
Photo Documentation Questions
How should I photograph cracks for monitoring?
Same angle every time. This matters more than anything else. Pick a spot where you'll stand, ideally where you can brace your phone against something for consistency. Include a ruler or tape measure in the frame for scale. Use your phone's flash so the lighting is similar regardless of time of day or season.
I tape a small piece of blue painter's tape to the wall about 6 inches from each crack I monitor. That tape is my "stand here and aim at this" reference point. Sounds dumb. Works great.
Take at least two shots each time. One close-up showing detail and scale, and one wider shot showing the crack in context, where it sits on the wall, and which direction it runs.
Can I use my phone's measurement tools to measure crack width?
Some phones have built-in measurement apps that use the camera and AR technology. Apple's Measure app, for example. These are fine for measuring large things like rooms or furniture. They are not accurate enough for crack widths.
We're talking about differences of 1/32 of an inch. Your phone's AR measurement tool has an error margin larger than that. The National Institute of Standards and Technology hasn't certified any smartphone-based measurement tool for this kind of precision, and for good reason.
A $12 crack gauge card held against the wall beats any phone app for width measurement. Buy one. Use it. That's the answer nobody wants to hear, but it's the right one.
What about photo comparison apps that overlay old and new images?
These actually have some value. Apps that let you overlay a current photo on top of an older one, adjusting transparency, can help you spot changes you might miss with side-by-side viewing. Some camera apps have a "ghost image" feature that shows your previous photo as a transparent overlay while you frame the new shot.
I used this approach for about a year. It's useful but finicky. You have to get the angle and distance almost exactly right for the overlay to line up. If you're off by even a few inches, the comparison is meaningless.
Honestly, I went back to side-by-side comparison in my photo library. Less cool. More reliable.
Digital Level and Tilt Questions
Can I use a digital level app to check if my walls are plumb?
Yes, with caveats. Most phones have an accelerometer that can function as a basic level. The built-in level tools on iPhones and most Android phones are accurate to about half a degree, which is good enough to detect significant wall tilt.
I used my phone's level app to check a wall that I suspected was bowing. The phone showed a 1.5-degree lean. When the structural engineer came out, his professional level measured 1.3 degrees. Close enough to confirm the problem, but I wouldn't have trusted the phone alone to determine whether that amount of tilt was acceptable or not.
Digital level apps are a decent screening tool. If your wall shows zero tilt on the app, it's probably fine. If it shows noticeable tilt, get a professional measurement. Don't rely on the app's exact number.
Are there sensors I can attach to my foundation for continuous monitoring?
Yes, and they range from simple to expensive. On the simple end, you can buy tilt sensors and vibration monitors that connect to your phone via Bluetooth. Prices range from $30 to $200 per sensor. They'll alert you if movement exceeds a threshold you set.
On the professional end, companies install strain gauges, tilt meters, and crack displacement sensors that feed data to monitoring platforms. These cost thousands to install and sometimes carry monthly monitoring fees.
For a typical homeowner watching a few stable cracks? Total overkill. My friend Dave looked into smart sensors for his house and got a quote for $3,500 to install six wireless tilt sensors with a monitoring dashboard. He bought a crack gauge and a notebook instead. Five years later, his cracks haven't moved. He saved $3,488.
Practical Questions
What should I use to organize my monitoring data?
Whatever you'll actually keep up with. I've tried spreadsheets, dedicated apps, and a plain notebook. The notebook won. It sits on a shelf in my basement. When I check cracks, I grab it, write the date, note each crack's measurement, and put it back. Takes five minutes.
Photos go in folders on my phone organized by year and month. I back them up to cloud storage so I don't lose them if my phone dies. That's my whole system.
Gary tried using a spreadsheet with color-coded columns and graphs. He maintained it for three months and then stopped entirely. Rick uses a yellow legal pad. He's been using the same system for 20 years. Simple wins.
When is technology actually better than a pencil and crack gauge?
Three situations.
First, when you need to share information with a professional. Emailing a structural engineer a folder of dated photos with a ruler in each frame is incredibly useful. Way better than saying "I think the crack got bigger." Photos with scale references are evidence. Your memory is not.
Second, when you're monitoring many cracks across a large property. If you have 15 or 20 cracks to check, a digital system with location tags and photo attachments keeps things organized better than a notebook.
Third, when you need continuous monitoring between check-ins. If an engineer has told you a wall is actively moving and you need to watch it closely, a tilt sensor that alerts your phone is worth the money. But this is a specific, temporary situation. Not everyday homeowner monitoring.
Should I buy a thermal camera attachment for my phone?
Thermal cameras ($200-400 for a phone attachment like FLIR One) can detect moisture behind walls, which can indicate water intrusion related to foundation cracks. They're genuinely useful tools.
But for crack monitoring specifically? No. A thermal camera tells you about temperature differences and moisture. It doesn't measure crack width, track crack growth, or assess structural significance. It's a different tool for a different problem.
If you're dealing with water coming through foundation cracks, a thermal camera can help you trace the moisture path. If you're just watching whether a dry crack is getting bigger, save your money.
What's the minimum technology setup for effective monitoring?
A phone with a camera, a crack gauge card, and a pencil. Total cost beyond the phone you already own: about $15.
Take photos with a ruler in the frame. Measure with the crack gauge. Write dates and measurements in a notebook or your phone's notes app. Check quarterly. Compare photos annually.
That's it. I've been monitoring cracks for twelve years with roughly this setup. My uncle spent $22,000 on underpinning because he didn't monitor at all and a foundation company scared him into unnecessary repairs. The problem isn't that people need better technology. The problem is that people either don't monitor or they panic and skip straight to hiring someone without any data.
A pencil mark and a dated photo are more powerful than any app. They give you the one thing no technology can manufacture: a history of what your foundation has actually done over time.