In Southern Utah, the ground beneath our feet isn’t as stable as it looks. Washington and Iron counties are home to some of the most problematic soils in the region—soils that shift, swell, and collapse with little warning. We’ve seen homes lift inches off their foundations and others sink silently over time. These aren’t rare events—they’re well-documented soil behaviors that every builder, buyer, and property owner should understand.
The culprits? Two distinct conditions: heave and settlement.
In this article, I’ll explain what causes these phenomena, how to recognize the signs, and why understanding your soil could be one of the smartest investments you make in any structure.
What Causes Heave?
Heave is the upward movement of soil, usually triggered when expansive clay soils absorb water and swell. These clays common across Washington and Iron counties can dramatically increase in volume when wet and shrink when dry. That cyclical lifting and dropping motion puts powerful stress on structures above.
Heavy rains, irrigation leaks, or landscaping changes can all spark the cycle. Entire corners of a slab-on-grade foundation may rise, leaving the structure to absorb the strain. Over time, this movement deforms floors, misaligns door frames, and cracks walls.
What Causes Settlement?
Settlement is the downward movement of soil. In Southern Utah, this often stems from:
- Collapsible soils: Loose, dry soils that consolidate rapidly when water is introduced.
- Poorly compacted fill: Soil added during construction that wasn’t compacted properly.
Settlement can happen quickly or be subtle but persistent, dragging parts of a structure downward and distorting its shape.
Key Signs of Foundation Movement:
- Raised or depressed sections of flooring: Wood may bulge, tiles pop, carpets ripple.
- Cracks at doors and window frames: Especially diagonal ones that widen.
- Sticking doors and windows: Often caused by uneven movement of the frame.
- Uneven floors: Furniture leans, balls roll, walking feels off-kilter.
- Stair-step cracks in brick or block: Especially near corners or openings.
- Gaps in finishes: Trim separating, baseboards lifting, or crown molding detaching.
What to Expect from Your Engineer: Questions to Ask About Your Soil
Engineers working in this region must treat soil conditions as a design priority. The prevalence of expansive clays and collapsible soils makes early evaluation essential.
At Strata, we don’t perform geotechnical testing in-house—but we know when it’s needed and can recommend trusted geotechnical engineers. We also help clients interpret findings and make practical decisions based on the results.
If your project warrants it, we may suggest:
- Soil investigations: Drilling, sampling, and observing site conditions.
- Lab testing: Swell potential, Atterberg limits, moisture-density relationships.
- Foundation guidance: We help clients and design teams review geotechnical reports to select appropriate foundation systems and grading strategies.
Understanding your soil type early allows for smarter choices—from deep piers to moisture control—that can prevent years of costly repairs and disputes.
Things to Watch with Your Realtor: Spotting Soil-Related Red Flags
Foundation movement can derail sales, impact valuations, and trigger future liability. In Washington and Iron counties, soil behavior is not just background noise, it's a central risk factor.
As a homebuyer or seller, your realtor is often the first set of eyes on a property. Spotting the early signs of movement can make or break a deal. Keep an eye out for:
- Uneven floors or shimmed furniture
- Cracks in stucco, drywall, or masonry
- Pooling water or poor drainage near the foundation
Asking for a pre-listing or pre-purchase engineering evaluation adds transparency, builds trust, and helps everyone move forward with confidence.
FAQ: Heave and Settlement Basics
What’s the difference between heave and settlement? Heave is upward soil movement caused by increased moisture in clay soils; settlement is downward movement due to soil collapse or poor compaction.
How can I tell what’s happening? The subtleties of settlement and heave are too difficult for self diagnosis. For example, a bulge in the floor may be an area of heave due to a plumbing leak or the perimeter may be settling due to poor drainage. An engineering evaluation and floor elevation measurements can clarify the condition.
Is soil movement seasonal? Yes. it can be -- particularly for expansive soil conditions. In wet seasons clays swell; during dry periods the moisture can evaporate and clays shrink. This seasonal rhythm drives cyclical movement.
Can irrigation or landscaping cause issues? Definitely. Overwatering, poor grading, or planting too close to a foundation can destabilize soils and trigger movement.
Should I walk away from a home showing signs of movement? Not necessarily. Many issues are manageable. What matters most is understanding what’s happening—why, and cost of mitigation—before making a decision.
Need Clarity? Let’s Talk
At Strata Consulting Engineers, we combine decades of engineering experience with real-world problem-solving in the field. If you’re dealing with signs of movement or just want to be proactive—reach out for a consultation or virtual site review.