Expansive Soils and Foundations Guide: Denver

Overview

Expansive soils contain clays that swell when they absorb water and shrink as they dry. Parts of Colorado's Front Range are known for expansive soils and bedrock, and the resulting movement can crack foundations, slabs and walls, and lift or drop parts of a house.

Water management is a central part of living with expansive soils. Keeping water away from the foundation, avoiding heavy irrigation right next to the house and maintaining gutters and grading help reduce swings in soil moisture.

For structural support, deep foundations such as piers that reach below the most active soil layers are common in new construction. In repair, piers and drainage improvements are typical tools, and some basement floors are designed to float so they can move independently of the walls.

What to expect, step by step

Reviewing drainage, irrigation and grading.
Evaluating soil type and signs of heave or settlement.
Evaluating slab movement and interior partition walls.
Recommending structural repairs, such as piers, where needed.
Recommending water management improvements.

Things worth considering

Heave is upward movement and can be mistaken for settlement.
Irrigation near the foundation can contribute to soil swelling.
Some homes have floating slabs and slip joints designed to accommodate movement.
Repairs can reduce movement but may not eliminate it.
Engineers familiar with local soils can be valuable.

Local notes for Denver

Parts of Colorado's Front Range are known for expansive clay soils and claystone bedrock that swell when wet and shrink as they dry. That movement can affect foundations, basement slabs, driveways and sidewalks, and it is one reason many local homes are built with deep foundations or floating basement slabs.

Front Range weather brings freeze-thaw cycles, spring snowmelt and summer storms. Keeping water away from the foundation with working gutters, extended downspouts, grading that slopes away from the house and careful irrigation near the foundation is a common first step before or alongside any repair.

We take inquiries from Denver, Aurora, Lakewood, Littleton, Arvada, Westminster.

Getting ready to reach out

Describe whether water shows up in the basement, crawl space or against the foundation, and when.
Note when you first noticed the problem and whether it seems to be getting worse.
Note the age of the home and whether it has a basement, crawl space or slab.
Mention any previous foundation, drainage or concrete work, and whether a warranty came with it.
Mention any doors or windows that stick, no longer latch or show new gaps.

When to keep looking

Refusal to let you get a second opinion or an engineer's review.
Pressure to sign the same day, or claims that a discount disappears if you wait.
No plan for restoring landscaping, walkways or finishes disturbed by the work.
Vague warranty terms, or no answer about whether the warranty transfers to a new owner.
No mention of permits for structural work where your jurisdiction requires them.

Questions worth asking

Is my home experiencing heave, settlement or both?
Are there signs of movement in my basement slab or partition walls?
How will repairs account for continued soil movement?
Would piers help in my situation?
Should I consult a geotechnical or structural engineer?

Quick answers

Are expansive soils common in Colorado?: Yes, parts of the Front Range are known for expansive soils and bedrock.
What are expansive soils?: Soils with clays that swell when wet and shrink when dry, causing movement.
What is a floating slab?: A basement floor designed to move independently of the foundation walls to accommodate soil movement.

Expansive Soils and Foundations in Denver