Getting Started Questions
How to begin monitoring.
What equipment do I need to monitor cracks?
Bare minimum: pencil and your phone camera. Better setup: carpenter's pencil, crack gauge card ($10-15), tape measure, flashlight, notebook. Total investment under $30.
I bought a crack gauge online and use a regular notebook. That's all I've ever needed.
How do I mark a crack for monitoring?
Draw a short line across each end of the crack. Date it. If the crack extends past your mark later, it's growing. Draw a line across the crack at its widest point. If the line separates into two lines, the crack is widening.
Simple, effective, zero cost beyond a pencil.
What's a crack gauge and do I need one?
A crack gauge is a clear card with lines of different widths printed on it. You hold it against a crack and match the width. More precise than eyeballing.
Useful but not essential. You can compare crack width to a coin edge or business card thickness. A gauge is just more accurate and consistent.
Technique Questions
How to do it right.
How often should I check my cracks?
Monthly for the first year. After that, quarterly is fine. After a few stable years, twice a year is enough. I check in spring after thaw and fall before winter.
More frequent checks in the first year help you establish patterns and build confidence.
What should I record each time?
Date, crack identification (I number mine), width measurement at the marked spot, and whether the crack has extended past end marks. Note anything unusual. Takes maybe 5 minutes per crack.
How do I take good photos for comparison?
Same angle every time. Same lighting if possible. Include a ruler in the frame for scale. Store photos in dated folders so you can compare over time.
My photo folders go back five years. Looking at year-one versus year-five side by side shows clearly that nothing has changed.
Should I measure in summer or winter?
Both, eventually. Cracks can be slightly wider in winter due to concrete contraction. Measure at consistent times so you're comparing apples to apples. Seasonal variation within a consistent range is normal.
What Changes Mean Questions
Interpreting your data.
What if a crack is slightly wider in winter?
Probably thermal. Concrete contracts when cold, cracks open slightly. Same crack might be slightly narrower in summer. Track over multiple years. If the winter width is consistent year over year, that's just seasonal variation.
My widest crack varies by maybe 1/32 inch between summer and winter. Same pattern every year. Not a problem.
What change should concern me?
Progressive change in one direction. Each reading wider than the last. Crack extending past end marks. Those indicate active movement, not just seasonal breathing.
Gary's monitors showed clear progression over months. Each reading was worse than before. That's the red flag.
How much change is significant?
Any clear trend matters more than absolute numbers. A crack that goes from 1/16" to 1/8" over a year is clearly growing. A crack that fluctuates between 1/16" and 1/8" seasonally is probably just responding to temperature.
Context and pattern matter more than any single measurement.
How long should I monitor before deciding?
At least one full year to see seasonal cycles. Two years gives you more confidence. If nothing has changed in two years of consistent monitoring, the crack is almost certainly dormant.
I monitored for about 18 months before I stopped worrying and relaxed my schedule to twice-yearly checks.