Foundation maintenance

Geology.com describes the mechanism plainly: expansive clay minerals absorb water and swell, then shrink as they dry, applying repetitive stress that worsens damage over time. Anything you do that keeps the soil around your foundation at a more constant moisture level reduces that cycling.

In practice that means: downspouts discharging several feet away rather than at the wall, gutters that actually flow, ground graded to fall away from the house, and irrigation that is not soaking one side of the foundation. In dry regions, some homeowners water foundation soil during drought for the same reason — to avoid extreme shrinkage. Whether that is appropriate depends on your soil, so ask a local engineer rather than following a general rule.

The economics are lopsided. HomeCostLab notes drainage improvements can come in under $1,000, against piering jobs that Today's Homeowner puts at $7,000 to $30,000. Even if drainage work does not prevent every problem, it is the best cost-to-benefit item available.

Keep a simple annual record. Photograph the same cracks each year on the same date. Over five years that file tells you and any future buyer more than any inspection report will.

How to choose

Downspouts first

Extending downspouts away from the wall is the highest-value, lowest-cost thing most homeowners can do.

Check the grade after any landscaping

New beds, mulch and hardscape routinely reverse the slope so water runs toward the house instead of away.

Watch irrigation placement

Sprinkler heads soaking one elevation of the house create exactly the uneven soil moisture that drives differential movement.

Trees are situational, not automatically bad

Large trees can draw significant moisture from clay soils. Whether one near your house is a problem is a site question, not a rule.

Photograph annually

Same cracks, same angle, same date each year. Costs nothing, worth a lot in a dispute or a sale.