Why Cracks Change With Seasons
Soil moisture drives most seasonal crack movement. When soil dries out in winter (or during drought), it shrinks away from your foundation. This can allow walls to move slightly, opening cracks. When soil rehydrates in spring and summer, it expands against the foundation, pushing walls back and closing cracks.
The effect is strongest with clay soils, which expand and contract dramatically with moisture changes. Sandy soils show less seasonal variation. But almost every foundation sees some movement through the year.
The Winter vs Summer Pattern
In my part of Ohio, the typical pattern looks like this:
- Late winter (Feb-March): Cracks at their widest. Ground is frozen or very dry.
- Spring (April-May): Cracks start closing as snow melts and spring rains saturate soil.
- Summer (June-August): Cracks at their narrowest. Humid air and regular rain keep soil moisture stable.
- Fall (Sept-Nov): Cracks start opening as soil dries out before winter.
Your region might differ. In areas with monsoon seasons or prolonged drought, the pattern shifts accordingly. The key is identifying what's normal for your specific location and soil type.
How to Track Seasonal Movement
I use a crack gauge on my main basement crack. It's a plastic overlay with graduated lines that shows movement down to 1/32 inch. Installed it in 2014 and check it monthly.
The important thing is comparing like to like. January 2026 versus January 2025. Not January versus July. Seasonal variation can be 1/16 inch or more, which looks dramatic if you don't understand the pattern but is completely normal.
My Recording Method
I keep a simple spreadsheet with date, crack width, and recent weather notes. After a few years, clear patterns emerge. My crack opens about 1/32 inch wider than average after dry spells and closes tight after heavy rain. That consistency actually reassured me more than anything. Random movement would worry me. Predictable seasonal movement is just the house doing what houses do.
When Seasonal Movement Becomes Concerning
Seasonal cycling itself is normal. What's not normal:
- Increasing amplitude: If the winter width keeps getting wider year over year while summer width stays the same, the crack is growing.
- One-way movement: Crack opens but never fully closes back. This suggests progressive settlement.
- Breaking the pattern: A crack that suddenly opens during summer or doesn't follow its established seasonal rhythm.
- Accompanying symptoms: Doors sticking, floor slopes, new cracks appearing during the same period.
What I Tell Friends
When neighbors ask about their cracks, I tell them to wait a year before deciding on repairs. Put a crack gauge on it, track it through all four seasons, and see what it actually does. Most of the time, they discover the crack is stable. It just looks different depending on when you measure it.
The contractor who scared me in 2012 measured in February. If he'd come back in August, that same crack would have looked much less alarming. Maybe he knew that, maybe he didn't. Either way, I would have been better off with seasonal data before making a $14,000 decision.