You’re probably thinking, “Hey, I’m supposed to keep water away from my foundation, so what gives? Why shouldn’t my trees soak up what water there is?”

Yes, you want to keep water from pooling around your foundation — that’s where your gutters, your downspouts, and properly graded soil comes in — but moist soil actually helps keep homes from settling unevenly, which can lead to cracks in foundations, facades, and walls.

During dry spells, when mature trees and shrubs grab scant moisture, soils shrink and foundations may settle. This can be particularly problematic in areas like the Ohio Valley westward, where homes rest on on “fat clay” — soil that greatly expands and contracts depending on moisture.
 
If a foundation settles evenly, damage is nil or minimal. But typically moisture levels, sunlight, and landscaping differ on each side of a house, causing soil to dry out and the house to settle unevenly, called “differential settlement.”

“That’s when you start to see cracks,” says Tom Scott, a structural engineer in Texas.

Signs your foundation is settling unevenly

  • Cracks in brick, drywall, tile, and stucco.
  • Sloping floors.

Floors slope gradually and are sometimes hard to notice. Use the marble test: Drop a few marbles on the floor and see where and how quickly they roll to the wall: The faster they roll, the greater the slope.

Settlement prevention

The best way to prevent your home from sinking during drought is to keep the soil around your home well hydrated.

  • Dig down about 6 inches; if the soil is bone dry, it needs water.
  • Run a soaker hose around the house about a foot away from the foundation, and let it water the soil until it’s moist — not drenched. That should give nearby drought-stricken trees a drink and keep the soil from contracting.

If you can, a preventative strategy is to plant or transplant trees away from your foundation so roots won’t compete with your house for water during dry spells. Roots extend to edge of the tree’s leaf canopy; so if the branches touch the house, the tree’s too close.

Professional help

If you notice cracks, sloping floors, and sticky interior doors, you should call a professional.

  • A structural engineer will inspect your foundation and give you a report for $300-$800.
  • A single crack repair in a poured foundation will cost $400-800, depending on the damage.
  • Stabilizing and supporting a foundation with concrete or steel piers will cost $1,000-$3,000 each.