Heat dries out soil
Fresno's summers are extremely hot; National Weather Service records show 69 days at or above 100°F in 2021. Long, hot, dry summers pull moisture out of soil, and where soils contain clay, drying causes shrinkage. That can lead to settlement along the edges of slabs and footings, especially on the sunny south and west sides and near large trees that draw water from the soil. When winter rains return, the soil can swell again. That repeated cycle is a common cause of foundation movement in the Central Valley.
Keeping moisture consistent
The aim isn't to keep soil wet, but to keep its moisture more consistent through the year. Practical steps include:
- Keeping gutters and downspouts working, with downspouts discharging well away from the house.
- Grading soil so it slopes away from the foundation.
- Watering landscape beds near the house moderately and regularly through summer rather than letting soil crack and then soaking it.
- Keeping irrigation spray off foundation walls and fixing leaks promptly.
Slab leaks
Many Fresno homes are built on slabs with water lines underneath. A leaking line under the slab can wash out soil or cause it to swell, leading to cracks and uneven floors. Warm spots on the floor, the sound of running water and a rising water bill are signs. Have a plumber test the lines before or alongside any slab repair.
Rare freezes
Frost heave isn't a common concern in Fresno; NOAA's engineering weather data records only about 10 freeze-thaw cycles in an average year. Most foundation movement here comes from moisture changes, drainage and plumbing rather than freezing.
Additions and older homes
Additions, garage conversions and patios built on shallower footings than the main house can settle differently, creating cracks where old and new meet. Older homes on raised foundations may have deteriorated posts, piers or sill plates in the crawlspace. A thorough inspection should cover both.
Before you hire
Ask Fresno foundation contractors what's causing the movement, whether they measured floor elevations, which repair method they recommend and why, whether the plumbing should be tested, and whether an engineer and permit are involved. For major repairs, consider an independent structural engineer. Look up the contractor's California license with the CSLB.
Tracking cracks
Because Central Valley soils can move seasonally, it's worth tracking cracks through a full year before committing to a major repair, unless movement is clearly progressing. Mark each crack's ends and width with a pencil and the date, photograph it beside a ruler, and check monthly. Those records help a contractor or engineer tell seasonal movement from ongoing settlement.
Trees near the house
Large trees close to the foundation can draw a great deal of water from the soil in Fresno's hot summers. Before removing one, ask a foundation professional or engineer about the effect; sudden removal can let soil swell as it regains moisture.
Crawlspace homes
Older Fresno homes on raised foundations should have their crawlspaces checked for settled posts, deteriorated wood and signs of water. Fixing drainage and replacing damaged posts or piers is often less disruptive than people expect.