Soil Bearing Capacity Chart by State
The next thing builders look up after frost line
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Check frost depth first: frost line depth by zip code. Sizing for snow load: snow load by zip code. New to footing sizing? Start with the concrete footing size chart.
What Soil Bearing Capacity Means for Your Concrete Project
Soil bearing capacity is the load — in pounds per square foot — that the soil under your footing can carry without excessive settlement. It is the second number you need after frost depth, and it controls the width of every footing you pour. If you have already looked up your frost line and you are sizing footings, this is the next stop.
Here is the science: a foundation pushes down on the soil at a pressure equal to the load divided by the footing's bearing area. If that pressure exceeds the soil's bearing capacity, the footing settles, the foundation cracks, and the structure above it goes out of plumb. A 2,000 lb point load on a 12-inch-square pad creates 2,000 psf bearing pressure. The same load on a 24-inch-square pad creates 500 psf. Soil with 1,500 psf capacity is fine for the second case and fails for the first.
The IRC handles this through Section R401.4.1, which lists presumptive load-bearing values you can use without a sealed geotechnical report. This is the table every builder, designer, and code official references.
Key Rule: IRC Table R401.4.1
In lieu of a complete geotechnical evaluation, the values below shall be assumed (verbatim from IRC R401.4.1):
| Foundation Material | Presumptive Load-Bearing Value (psf) |
|---|---|
| Crystalline bedrock | 12,000 |
| Sedimentary and foliated rock | 4,000 |
| Sandy gravel and/or gravel (GW and GP) | 3,000 |
| Sand, silty sand, clayey sand, silty gravel, clayey gravel (SW, SP, SM, SC, GM, GC) | 2,000 |
| Clay, sandy clay, silty clay, clayey silt, silt, sandy silty clay (CL, ML, MH, CH) | 1,500 |
Per the code footnote: where the building official determines that in-place soils with allowable bearing below 1,500 psf are likely present, a soils investigation is required. Letter codes (GW, SP, CL, etc.) refer to the Unified Soil Classification System (ASTM D2487).
If you do not know your soil and your building official does not require a geotech report, IRC prescriptive footing tables in R403.1(1) assume 1,500 psf as the floor. That is the conservative default for residential design.
Soil Bearing Capacity by State: Reference Table
Unlike frost depth or snow load, IRC R401.4.1 presumptive values are not geographically variable — the table is identical in every state that adopts the IRC. What varies is which soil type your site actually contains, and whether your state requires you to prove it. The table below pairs the dominant near-surface soil at each state's residential building sites with the typical presumptive value and any code-relevant notes.
| State | Dominant Near-Surface Soils | Typical Presumptive (psf) | State / AHJ Notes |
|---|---|---|---|
| Alabama | Sandy clay, silty clay (Piedmont); sand (Gulf) | 1,500 – 2,000 | IRC base |
| Alaska | Glacial till; permafrost in interior | 1,500; permafrost = engineered | Geotech often required |
| Arizona | Caliche, sandy gravel | 2,000 – 3,000 | Expansive soils common in Phoenix |
| Arkansas | Silty clay, clayey silt | 1,500 | IRC base; Yazoo clay locally |
| California | Highly variable | 1,500 (default) | CRC R401.4.1.1 mandates preliminary soil report per Gov Code §66426 |
| Colorado | Expansive clay (bentonite) common | 1,500 | DFPC R401.4 requires geotech; Denver deletes presumptive exception |
| Connecticut | Glacial till | 2,000 | IRC base |
| Delaware | Sand, silty sand (coastal plain) | 2,000 | IRC base |
| Florida | Sand (peninsula); limestone (south) | 2,000 – 4,000 | FBC-R adopts IRC verbatim |
| Georgia | Sandy clay (Piedmont); sand (coastal) | 1,500 – 2,000 | IRC base |
| Hawaii | Volcanic ash, basalt | 1,500 – 4,000 | County-specific |
| Idaho | Volcanic loess, glacial gravel | 1,500 – 3,000 | IRC base |
| Illinois | Silty clay glacial till | 1,500 | IRC base |
| Indiana | Silty clay glacial till | 1,500 | IRC base |
| Iowa | Loess, glacial till | 1,500 | IRC base |
| Kansas | Silty clay, loess | 1,500 | IRC base |
| Kentucky | Residual silty clay over limestone | 1,500 – 4,000 | Karst caution near Mammoth Cave |
| Louisiana | Soft alluvial clay (south); silt (north) | 1,500 or less | Soils investigation common in Gulf zone |
| Maine | Glacial till, sandy gravel | 2,000 – 3,000 | IRC base; marine clay locally |
| Maryland | Sandy clay (Piedmont); sand (coastal) | 1,500 – 2,000 | IRC base |
| Massachusetts | Glacial till, sand | 2,000 – 3,000 | IRC base |
| Michigan | Sandy glacial till | 2,000 | IRC base |
| Minnesota | Sandy/clayey glacial till | 1,500 – 2,000 | IRC base |
| Mississippi | Yazoo clay (Delta), sand | 1,500 or less | Geotech recommended in expansive zones |
| Missouri | Silty clay, loess | 1,500 | IRC base |
| Montana | Bentonitic shale, gravel | 1,500 | Expansive soils in eastern plains |
| Nebraska | Loess, sandy alluvium | 1,500 – 2,000 | IRC base |
| Nevada | Caliche, alluvial gravel | 2,000 – 3,000 | IRC base |
| New Hampshire | Glacial till, sandy gravel | 2,000 – 3,000 | IRC base |
| New Jersey | Sandy soils (coastal); silty clay (NW) | 1,500 – 2,000 | IRC base |
| New Mexico | Sandy clay, caliche | 1,500 – 2,000 | Expansive soils in central NM |
| New York | Glacial till, marine clay (NYC) | 1,500 – 3,000 | NYC has separate soil class table |
| North Carolina | Sandy clay (Piedmont) | 2,000 default | NCRC R401.4.1 footnote b: values above 2,000 psf require engineering evaluation |
| North Dakota | Bentonitic clay, glacial till | 1,500 | Expansive soils common |
| Ohio | Silty clay glacial till | 1,500 | IRC base |
| Oklahoma | Silty/sandy clay; Permian red beds | 1,500 | Expansive clay common in OKC |
| Oregon | Volcanic loess, basalt | 1,500 – 4,000 | IRC base |
| Pennsylvania | Residual silty clay, glacial till | 1,500 – 2,000 | IRC base |
| Rhode Island | Glacial till, sand | 2,000 – 3,000 | IRC base |
| South Carolina | Sandy clay (Piedmont); sand (coastal) | 1,500 – 2,000 | IRC base |
| South Dakota | Bentonitic shale, loess | 1,500 | Expansive soils common |
| Tennessee | Residual silty clay over limestone | 1,500 – 4,000 | Karst caution |
| Texas | Highly expansive clay (Blackland Prairie) | 1,500 (rarely used) | Engineered post-tensioned slabs standard in central/north TX |
| Utah | Bonneville lacustrine clay, sand | 1,500 – 2,000 | Expansive soils in Wasatch Front |
| Vermont | Glacial till, marine clay (Champlain) | 1,500 – 2,000 | IRC base |
| Virginia | Sandy clay (Piedmont); sand (coastal) | 1,500 – 2,000 | Shrink-swell soils in Tidewater |
| Washington | Glacial till, volcanic ash | 2,000 – 3,000 | IRC base |
| West Virginia | Residual clay, sandstone | 1,500 – 4,000 | Karst/landslide caution |
| Wisconsin | Sandy glacial till | 2,000 | IRC base |
| Wyoming | Bentonitic clay, gravel | 1,500 | Expansive soils common |
Sources: IRC Table R401.4.1, USDA NRCS Web Soil Survey (SSURGO), state geological surveys, USGS Swelling Clays Map I-1940, and state-specific building code amendments. Site-specific values require a geotechnical report.
City-Level Soil Bearing Conditions to Watch
The IRC table itself does not vary by city, but some metros have hazardous soil conditions that warrant extra design care or routinely trigger geotechnical investigations regardless of the presumptive table.
| City | State | Watch For |
|---|---|---|
| Houston | TX | Highly expansive Beaumont/Lissie clays |
| Dallas / Fort Worth | TX | Blackland Prairie clay, PI > 30 |
| Denver | CO | Bentonite swelling clays; geotech mandated |
| Colorado Springs | CO | Expansive clay and shale |
| Oklahoma City | OK | Permian red bed clays |
| Salt Lake City | UT | Lacustrine clays, liquefaction zones |
| San Francisco / Oakland | CA | Bay mud, liquefaction; CRC report required |
| Los Angeles | CA | Expansive clay, hillside cut/fill; LA County R401.4 A1 |
| Memphis | TN | Loess collapse, New Madrid seismic |
| Minneapolis | MN | Variable till and peat |
| New Orleans | LA | Soft organic clay, often <1,500 psf |
| Boston | MA | Boston Blue Clay; varies block to block |
| Fargo / Bismarck | ND | Lake Agassiz clays, expansive |
| Cheyenne | WY | Steppe clays, expansive |
| Phoenix | AZ | Caliche layers, expansive clays in fans |
In each of these metros, a presumptive 1,500 psf design is not technically illegal, but it is poor practice without a soils report.
State Amendments That Change How R401.4.1 Is Used
Three states meaningfully modify how the IRC presumptive table is applied. If your project is in one of them, do not rely on the default values.
California — Mandatory Preliminary Soil Report
The California Residential Code at R401.4.1.1 requires every city and county to enact an ordinance mandating a preliminary soil report by a registered civil engineer for every new subdivision under Government Code §66426. If the report shows critically expansive soils, lot-by-lot soil investigation follows. The numerical table is unchanged, but you cannot rely on presumptive values for new subdivisions in most California jurisdictions. Los Angeles County's RCM R401.4 A1 further restricts presumptive Table R401.4.1 use to specific soil classes only.
North Carolina — 2,000 psf Cap on Presumptive Design
NCRC R401.4.1 footnote (b) reads: "The load bearing values greater than 2,000 psf in Table R401.4.1 require an engineering evaluation." And: "Where the building official determines that in-place soils with an allowable bearing capacity of less than 2,000 psf are likely to be present at the site, the allowable bearing capacity shall be determined by a soils investigation." In effect, NC's presumptive design ceiling is 2,000 psf; anything higher needs an engineer. Standard footing tables in the NC code are based on 2,000 psf bearing.
Colorado — Geotech Mandated for New Construction
Colorado's Division of Fire Prevention and Control Residential Code 2021 broadly amends R401.4 to require a geotechnical investigation report for new residential construction. The presumptive table is available only as an exception for additions, alterations, and repairs. The City and County of Denver further deletes the presumptive exception, requiring a geotech report on all permitted dwelling work. La Plata County substitutes a county-specific expansive-soil rule referencing the local soil survey.
Florida, Texas, Massachusetts, New York, and most other states adopt IRC Table R401.4.1 verbatim — though Texas's practical environment (Blackland Prairie clays) means the presumptive table is rarely the basis for actual foundation design in central and north Texas, where engineered post-tensioned slabs are standard.
How Soil Bearing Capacity Drives Footing Width and Cost
The IRC footing size tables — R403.1(1) for plain spread footings, R403.1(2) for pier footings — take three inputs:
- Number of stories supported (1, 2, or 3)
- Construction type (light-frame, brick veneer, masonry)
- Load-bearing value of the soil (psf)
For a 2-story light-frame house with brick veneer on 1,500 psf clay, the table typically requires an 18-inch-wide footing. The same house on 3,000 psf sandy gravel may need only 12-inch footings. Across 200 linear feet of perimeter footing, the soil value alone drives:
- ~3 cubic yards of additional concrete (about $500 at $150/yd³ delivered)
- ~50% more excavation volume
- More rebar, more form lumber, more labor
In total, the difference between assuming 1,500 psf and proving 3,000 psf can save $1,500–$3,000 on a modest residential project. That is why a $2,000 geotechnical report often pays for itself, especially in mid-range bearing soils.
Sizing a footing? See our concrete footing size chart for the IRC tables, plug your dimensions into the concrete footing calculator, or use the strip footing calculator for continuous wall foundations. Cross-check footing depth with frost line depth by zip code, and verify roof-derived loads with snow load by zip code.
How to Verify Soil Bearing Capacity at Your Site
Step 1: Default to 1,500 psf
For prescriptive design under the IRC, this is your safe default in the absence of a soils report. Most residential footing tables are pre-sized to this value, so building to 1,500 psf is always code-compliant — it just may not be cost-optimal.
Step 2: Pull USDA NRCS Web Soil Survey
Go to websoilsurvey.nrcs.usda.gov/app, drop an Area of Interest polygon on your lot, and run the Building Site Development ratings and Engineering Properties reports. This will not give you a single psf number — Web Soil Survey does not publish bearing capacity directly — but it identifies the dominant soil series, USCS class (CL, SM, SW, etc.), shrink-swell potential, and water table depth. Cross-reference the USCS class to IRC Table R401.4.1.
Step 3: Check Your State Geological Survey
Almost every state geological survey publishes hazard maps for expansive clays, karst, and unstable slopes. For shrink-swell at the national scale, USGS Map I-1940 (Swelling Clays Map of the Conterminous United States) is the canonical reference. State surveys add detail: the Colorado Geological Survey publishes expansive soil maps; the Texas Bureau of Economic Geology publishes soil and geologic atlases; California Soil Resource Lab SoilWeb overlays SSURGO on Google Maps.
Step 4: Order a Soils Report When the Stakes Justify It
A residential geotechnical report runs $1,000–$5,000, averaging around $2,700 per 2026 cost data. The report includes 2–3 borings, sieve and Atterberg testing, and a stamped recommendation. For any project above $50,000, a slab on suspected expansive clay, or any site the building official flags, that report is cheap insurance — and often pays for itself in reduced footing concrete on competent soils.
Plan Your Foundation on the Right Number
Soil bearing capacity is the second leg of the three-legged stool: frost depth tells you how deep, snow load tells you how heavy from above, and bearing capacity tells you how wide. Get all three right and your foundation has a 50-year service life. Get any one wrong and you are chasing cracks.
Use the table above to set expectations, the USDA Web Soil Survey to identify your dominant soil class, and a geotechnical report when the project value or soil risk warrants it. Then let our calculators handle the math on how much concrete you actually need.
Frequently Asked Questions
What is the default soil bearing capacity if I have no soils report?
1,500 psf. This is the IRC presumptive value for clay and silt under Table R401.4.1, and it is what most residential footing tables in R403.1 assume.
My soil report says 4,000 psf. Can I use that?
You can if the report is sealed by a licensed geotechnical engineer and your building official accepts it. IRC R401.4.1 enumerates presumptive values up to 12,000 psf; some state amendments (notably North Carolina) require an engineering evaluation above 2,000 psf regardless of source.
Does Table R401.4.1 apply to deep foundations?
No. R401.4.1 covers shallow spread footings only. Piles, helical piers, and drilled caissons are designed per a stamped engineering analysis referencing IBC Chapter 18.
What about expansive clay in Texas, Colorado, and the Plains?
Presumptive values do not capture shrink-swell behavior. In active expansive-clay regions, engineered post-tensioned slabs or pier-and-beam foundations are standard. IRC R403.1.8 references IBC §1808.6 for expansive-soil design and triggers a soils investigation when plasticity index ≥ 15 plus three other criteria.
What is the "USCS" classification in the IRC table?
Unified Soil Classification System per ASTM D2487. SW = well-graded sand, GP = poorly-graded gravel, CL = lean clay, ML = silt, MH = elastic silt, CH = fat clay, GW/GM = gravel variants. Your soils engineer reports USCS classes from sieve and Atterberg tests; the IRC table maps those to a presumptive psf.
Can I use plate load testing to set a higher value?
On commercial projects, yes. In residential work it is rare and usually not worth the cost. Most jurisdictions accept a stamped geotechnical report based on standard penetration testing (SPT).
How much does a geotechnical report cost?
Between $1,000 and $5,000, with the typical residential investigation averaging around $2,700 per 2026 cost data. Cost scales with number of borings, depth, and lab testing required.
Where exactly does R401.4.1 live in the code?
IRC Chapter 4 (Foundations), Part R401 (General), Section R401.4 (Soil Tests), Subsection R401.4.1 (Geotechnical Evaluation). The presumptive table is published as Table R401.4.1.