What the clay does
| Colorado Geological Survey | |
|---|---|
| Clays involved | Bentonite and montmorillonite (weathered volcanic ash), as soil or soft bedrock |
| Swell | Up to 20% by volume when exposed to water |
| Pressure | Up to 30,000 lb per sq ft, "more than enough to break up any structure" |
| Typical damage | Structural damage, cracked driveways, sidewalks and basement floors, broken pipelines and sewer lines |
| Owner-side causes | Poor surface drainage, ponding near the foundation, plants and irrigation next to the walls |
| Design and build causes | Wrong drilled-pier depth or diameter, too little or misplaced rebar, "mushroom-topped" piers, no void space under grade beams, no allowance for basement floor movement |
The last two rows are the useful ones when a repair firm inspects: the cause sets the fix. A crack from a downspout dumping against the wall is a drainage job first; a pier problem is an engineering job.
What Denver requires
Denver's permitting checklist for new homes and additions requires a current geotechnical soils report for new dwellings, new conditioned accessory structures, additions on deep foundations, and "when expansive soils, compressible soils, shifting soils, or other questionable soil characteristics are likely to be present" (DRC R401.4). It also says "any structural designs which are not prescribed by the Denver Residential Code must be engineered." For a repair on your existing house, that means two questions for every bidder:
- Is there a stamped engineer's design? Piers, wall bracing and underpinning are not prescriptive work. Ask who the engineer is and whether the letter or drawings go in with the permit.
- Whose permit is it? Repair permits in our file are filed by the repair firm. Get the permit number in the contract and look it up afterwards in Denver's permit search.
If you are adding on as well as repairing, the soils report for the addition will tell you more about the ground than any sales inspection; ask the repair firm to read it.
What 951 Denver repair permits show
| Measure | Denver foundation & structural repair |
|---|---|
| Permits, October 2023 to September 2026 | 951 |
| Firms / active in the last year of data | 130 / 62 |
| Usual filed value | $12,220 |
| Middle half of firms' usual value (30 firms) | $9,870 to $26,100 |
| Usual days from issue to close | 93 |
| Closed (permits a year or more old) | 63.2% |
| Share held by the busiest firm / five busiest | 32.6% / 66.8% |
| Firms with 10 or more permits | 8 |
| Busiest / quietest month | December (132) / March (66) |
A handful of specialists do most of this work: the five busiest firms hold 66.8% of permits and only 8 firms filed ten or more. That makes comparison easy, because each of them has a track record you can count. The middle half of firms usually file between $9,870 and $26,100; a bid far above that range should come with an engineer's reason. Values by firm are on Denver repair cost.
Compare Denver foundation repair firms by permits →
Related
Costs elsewhere: foundation repair cost. Choosing the firm: hiring a foundation repair contractor. Permits in general: do I need a permit for foundation repair. Licenses: Denver contractor license lookup.
What this does not tell you
Our records do not say why a foundation failed or whether the soil was expansive; they show who filed structural repair permits, at what value and whether the permit closed. Filed values are the contractor's estimate, not the invoice. We cover the City and County of Denver only.
How we know this
Soil facts are from the Colorado Geological Survey's Expansive Soil and Rock page; permit requirements from Denver's Permitting Checklist for New Homes and Additions; both read 23 October 2026. Permit counts are City and County of Denver residential permits classified as foundation and structural repair, October 2023 to September 2026; the closed share uses permits a year or more old.
Numbers come from City and County of Denver residential construction and demolition permits, data through October 16, 2026. Nobody paid to be on this page and nobody can.
Questions
- Is expansive soil a problem in Denver?
Yes. The Colorado Geological Survey calls expansive or swelling soil Colorado's most significant geologic hazard and says bentonite and montmorillonite clays underlie many populated areas of the state. Those clays can expand up to 20% by volume when wet and exert up to 30,000 pounds per square foot.
- How much does foundation repair cost in Denver?
On the permit, the usual Denver foundation and structural repair job was filed at $12,220 (951 permits, October 2023 to September 2026). The middle half of firms with three or more permits usually filed between $9,870 and $26,100.
- Does Denver require a soils report?
For new homes, new conditioned accessory structures, additions on deep foundations, and any project where expansive, compressible or shifting soils are likely, Denver's permitting checklist requires a current geotechnical soils report (DRC R401.4).
- How long does a foundation repair permit stay open in Denver?
Usually about 93 days from issue to close in our file, and 63.2% of permits a year or more old were closed.
- What makes expansive soil damage worse?
The Colorado Geological Survey lists poor surface drainage, water ponding near the foundation, and planting next to the house so irrigation water soaks the soil, along with design faults such as drilled piers of the wrong depth or diameter and too little reinforcing steel.
Build your own list
Every firm with that kind of permit on record. Pick what you value. The list moves.
Related guides
- Denver building permit search: e-permits, attachments and CORA requests
- Denver contractor license lookup: city licenses, state trade licenses and the permits
- Home improvement costs in Denver, CO (2026): what 8 kinds of jobs were filed at
- Foundation repair cost in 2026: what foundation permits were filed at in 12 cities
For one city
- Denver ADU rules since citywide ADUs: owner occupancy, the licensed-contractor rule, and what ADU permits were filed at
- Tearing down a house in Denver: the 40% rule, Landmark Preservation review, and the 21-day posting
- Do I need a permit to build a garage in Denver? Zoning, building and sewer permits, fees and the old garage
- Expansive Soil and Rock — Colorado Geological Survey (accessed 2026-10-23)
- Permitting Checklist for New Homes and Additions — Denver CPD (accessed 2026-10-23)