The Three Cracks I Have Watched the Longest
My basement has three cracks I have been measuring since 2014. One is the original shrinkage crack on the east wall, the one the contractor said would cause 'catastrophic failure.' I have twelve years of width readings on it and it has not changed by a measurable amount. Its widest point is 1/32 of an inch and its narrowest is hairline. The same as the day I bought the house.
The second is a small diagonal crack at the corner of the basement window in the back of the house. That one has actually moved, but very slowly. In 2014 it measured about 1/64 of an inch. In 2026 it measures somewhere between 1/32 and 1/16 of an inch depending on the season. It is wider in summer and narrower in winter, which is normal thermal cycling. I am watching it but not worried.
The third is on the basement floor, near where the slab meets the wall. It is what is called a cold joint crack and it is essentially a separation between two pours of concrete that happened at different times during construction. It has stayed completely stable.
How I Actually Measure
I use two tools. The first is a Telltale brand crack monitor on the most active of the three cracks. I installed it in 2014 and have not touched it since except to read it. It has a sliding plate marked in millimeters and lets me see at a glance if anything has moved between visits. The second is a feeler gauge set I bought for $12 on the recommendation of a structural engineer I met at a homeowner workshop in 2017.
The feeler gauge is the thing that changed how I track cracks. Before that I was eyeballing crack widths and writing things like 'about the same as last time.' That is useless. With the feeler gauge I can write 'east wall crack, widest reading 0.030 inches at 18 inches from floor.' That is a real data point I can compare to a future reading.
Photo Documentation Routine
I take three photos per crack per visit. One wide shot showing the full crack, one close-up of the widest point with a small ruler in the frame, and one of the area around the crack to capture any new staining or efflorescence. I store them in a folder organized by year. After twelve years I have over 400 photos that show essentially no change. That is, in its own way, the most reassuring archive I own.
The Doors and Windows Check
Every walk includes a check of every interior door in the house plus the basement bulkhead door and both garage doors. I am looking for changes in how they latch, how they swing, and whether the gaps around them have changed. Foundation movement shows up in doors before it shows up in walls a lot of the time.
My friend Tomas in Worthington learned this the hard way. He noticed his bedroom door starting to stick in 2022 but did not connect it to anything until six months later when a crack opened up in his foyer drywall. By then there was real differential settlement happening on one side of his house. If he had been tracking the door, he would have caught it earlier. Not that earlier would have prevented the issue, his sewer line had broken under the slab, but he would have known to investigate sooner.
I have a list in my notebook of every door, every window, and which way each one tends to drift through the seasons. Most of them stick a little in summer and ease up in winter. That is wood doing its job.
Moisture Tracking
I check four spots in my basement for moisture every visit. The corner where the sump pump sits, the floor near the drain in the laundry area, the base of the east wall (where the monitored crack is), and the wall behind the workbench where there used to be a small water issue when I first moved in.
I am not using fancy equipment for this. I run my hand along the surface, look for staining, and use a cheap moisture meter from the hardware store on any spot that looks suspicious. The meter is not accurate enough to be diagnostic, but it is more than accurate enough to flag a change. If a reading goes up by ten points between visits, I want to know.
Moisture changes often show up before crack changes. Soil shifts around the foundation in response to drainage, water levels, and seasonal moisture, and that movement is sometimes detectable as new dampness before it becomes detectable as movement.
The Notebook Pages
Every visit gets one page in the notebook. Date at the top. Outdoor temperature and recent weather (a stretch of heavy rain or a dry summer matters). Then four sections: cracks, doors, moisture, other.
'Other' is where I write down anything that does not fit. New stain on the ceiling. A weird sound from the sump pump. The cracked tile in the bathroom that I should probably get to. Most of those entries lead nowhere. A few of them have caught real problems early.
In 2019 I noticed in my 'other' section that the same ceiling stain had appeared in two consecutive visits. Six months later I found the slow plumbing leak that had been dripping behind a wall. The notebook caught it because I had a written record of seeing the stain in November and then again in May. Without the notebook I would have forgotten about the November one entirely.
What I Do Not Track
I do not measure floor levelness with a marble or laser level on my home walkthroughs. That is something I had a contractor do once when I first bought the house to establish a baseline, but it is more work than I want to do twice a year, and any meaningful change would show up in doors and walls before it would show up as a measurable floor slope.
I do not crawl under the deck to inspect the foundation from the outside in winter. I do that in spring after the ground has thawed. There is no useful information to be gained by trying to read a foundation surface that has a layer of frost or ice clinging to it.
And I do not bother checking the brick veneer on the exterior every visit. Brick moves independently of foundation a lot of the time. I check the brick once a year, in summer, and only the corners and around the windows where any real movement would show up first.
When the Routine Turns Into a Call
In twelve years I have only called my engineer twice outside of the regular professional inspections. Once was in 2018 when one of the crack widths jumped from 0.030 to 0.045 inches in a single six-month interval. That turned out to be measurement error. The engineer remeasured and got 0.031. I had been pressing the gauge into the crack too hard.
The second was in 2023 when my neighbor's new addition went in twelve feet from my property line and I started seeing fresh dust at the bottom of one of my basement cracks. That one was real. The construction vibration had loosened some old debris in a crack that was otherwise stable. The engineer agreed it was not a structural concern but it was the kind of thing I would not have noticed without baseline photos to compare against.
The point of the routine is not to find problems. It is to know which observations to trust when something does show up. Twelve years of 'no change' makes it really easy to recognize a change when it finally happens.