Quick answer
Soil bearing capacity is the amount of pressure the ground under a footing can carry from a building without shearing or settling too far, so a foundation can pass its load safely into the soil.
It is not a fixed property of a soil name. It depends on the soil, its moisture, the footing size and depth, and how much settlement the building can tolerate, so it is set for a site by testing or by code.
Quick facts
The key facts about Soil Bearing Capacity, with sources:
- What it limits
- Pressure a footing may put on the soil, so loads pass to the ground safely 1
- Who sets it
- A geotechnical engineer by site evaluation, or the code’s presumptive table when no evaluation is done 1
- Code section
- IRC R401.4.1 geotechnical evaluation and Table R401.4.1 1
- Footing link
- Footing width is based on the soil’s load-bearing value 1
- Deep option
- Deep foundations reach soils or bedrock well below the surface 2
- Values on this page
- None. A bearing number belongs to a site report, not a glossary 1
Key takeaways
- Bearing capacity is the pressure ground can take from a footing before it fails or settles too far.
- It belongs to a site, not to a soil name. Moisture, fill, depth and footing size all change it.
- Model codes let designers use a presumptive table when no geotechnical evaluation is done, and they require a soils investigation where weak soil is likely.
- A footing is sized so the load, spread over its area, stays under what the soil can carry. A larger footing lowers the pressure.
- This page prints no bearing number. A value only means something with a site report from a qualified engineer.
What soil bearing capacity means
Every house puts weight on the ground. The foundation spreads that weight over an area, and the soil under it has to carry it.
Soil bearing capacity is the limit on how much pressure that soil can take from the footing.
Go past it, and the soil can fail by shearing, or it can settle farther than the building can tolerate.
General information, not a diagnosis of your house. The residential code describes the job in plain terms. Foundation construction has to accommodate the loads and transmit them to the supporting soil, and footings must carry loads to the soil within limits set by the character of the soil 1.
Two things are checked. One is strength: will the soil hold without shearing under the load? The other is settlement: will it compress so much that the structure cracks or tilts? Settlement can matter as much as strength when a footing is sized.
Bearing capacity vs. load-bearing wall
A load-bearing wall carries weight from the structure above it. Soil bearing capacity is about the ground below the footing. The two meet at the footing, where a wall’s load is passed to the soil.
Foundation load-bearing capacity: how the soil and the footing work together
A foundation’s load-bearing capacity comes from two things that work together: the soil under it and the footing that spreads the load. The footing turns a concentrated load from a wall or post into a lower pressure on the soil.
Penn State engineers note that footings distribute loads to the soil and give a platform for the foundation wall, and that they can bridge isolated areas of settled soil 3.
The residential code ties the two together. Footing width is based on the load-bearing value of the soil, and footings under piers and columns are sized from the tributary load and allowable soil pressure 1.
A wider footing gives a lower pressure on the same soil. A softer soil needs a wider footing, or a different foundation type.
The load travels in a chain: roof, walls, floors, footing, soil. If any link is weak, the chain bends at that point. See load path in residential buildings for the whole chain.
Vertical chain showing roof load passing into walls, then floors, then the foundation wall and footing, and finally into the soil, with arrows pointing down at each step.
Illustrative drawing of a load moving down through a house into the ground. It carries no numbers, is not to scale and is not a design.
Cross-section of a footing, stem wall, sill plate and floor framing sitting on soil, with the load from the wall passing down through the footing into the soil.
Illustrative drawing of a footing spreading a wall’s load into soil. It is not a design for any house.
How bearing capacity is determined: three routes
| Route | What it involves | When it is used |
|---|---|---|
| Presumptive value | The code’s table of load-bearing values by material class, used when a geotechnical evaluation is not done 1 | Typical small houses on ordinary soil, where the building official accepts it |
| Geotechnical evaluation | Borings or test pits, lab tests and an engineer’s recommendation for allowable bearing pressure 1 | Questionable soils, fill, weak soils, larger loads |
| Soil test by approved agency | The building official can require a test where expansive, compressible, shifting or other questionable soils are likely 1 | Where soil science data point to a problem |
Why this page gives no number
The code’s presumptive table lists values by soil class. We do not reprint them, because a number from a table is not a design value for your lot. Footnotes in the code say a soils investigation decides the value where weak soil is likely 1.
Example: how footing width and soil change the pressure
An illustration of the idea with no numbers. The load is the same in each case, and only the footing or the soil changes.
| Case | What changes | Effect on pressure on soil | What the designer does |
|---|---|---|---|
| Same load, narrow footing | Small bearing area | Higher pressure | Widens the footing if the soil allows 1 |
| Same load, wide footing | Large bearing area | Lower pressure | Checks that settlement is acceptable |
| Same footing, soft or wet soil | Weaker soil | Pressure may exceed what the soil can carry | Gets a soils investigation, or uses a deep foundation 12 |
| Same footing, soil stays dry and even | Steadier moisture | Capacity is easier to predict | Keeps drainage working |
Pressure is load divided by area, so a wider footing spreads the same load more gently. Footing sizes in real designs come from engineering tables and calculations, not from this illustration.
Where bearing capacity matters on a house
Bearing capacity matters at every footing: under exterior walls, under interior bearing walls, under piers and columns, and under a thickened slab edge.
The residential code says exterior walls are supported on continuous footings of concrete, masonry or other approved systems that carry all loads to the soil within limits set by the soil 1.
Footings must sit on undisturbed natural soil or engineered fill 1. A footing on loose, unprepared fill is a classic place for trouble. See fill soil and foundation settlement and soil compaction.
FEMA defines shallow foundations as supported by soils relatively close to the surface, and deep foundations as supported by soils or bedrock significantly below it 2. When shallow soil is too weak, deep foundations such as piles or drilled shafts reach stronger layers. Read shallow vs. deep foundations for the choice.
Why knowing the bearing capacity helps, and its limits
What a site value gives you
What it cannot tell you
- One value does not describe a whole lot, because soil varies from place to place.
- It does not predict moisture-driven movement. Clay can swell or shrink even where strength is fine 4.
- It says nothing about foundation quality, drainage or workmanship.
- It changes if water, fill or load changes after the report.
What soil bearing capacity does not explain
Strength is only part of the story. A soil can carry a load without shearing and still move with the seasons. NRCS rates shrink-swell separately from strength, and says that above a linear extensibility of 3 percent, shrinking and swelling can damage buildings and roads 4. Read expansive clay soil for that side.
Soil behavior depends on mineralogy, moisture, stress and drainage. One soil type is not proof of a problem, and one soil name is not proof of strength. Geotechnical testing may be needed to know which applies on your lot.
Bearing capacity also tells you nothing about a particular crack. A crack is a clue to movement history, not a bearing test.
What drives the cost of finding bearing capacity
We print no prices, because fair numbers need dated local quotes. The cost drivers are the number and depth of borings or test pits, the lab tests ordered, site access, how variable the soil is, whether the report must cover fill or groundwater, and the size of the building.
The report can lower the cost of the foundation itself by showing where a simple footing is enough and where it is not. For how quotes are built, read the foundation cost guide.
How a geotechnical engineer finds bearing capacity
A general outline of the process, not a scope for your lot:
- Plan the investigation: The engineer reviews the building loads, the site and the soil survey data.
- Sample the ground: Borings or test pits reach the depths that will carry load, and soil is logged and sampled.
- Test the samples: Lab tests measure strength, compressibility and other properties.
- Check groundwater and fill: Water level and the nature of any fill are recorded.
- Recommend values: The report gives allowable bearing pressure and settlement expectations, and says which foundation types suit the site 1.
- Review the design: A structural designer sizes footings from the recommendation.
Never dig or load footings yourself
Do not excavate beside a footing, add heavy loads on a slab edge, or pile fill against a wall to improve support. Changes in load and soil next to a foundation are engineering work.
What a homeowner can do to protect the soil under a footing
- Keep surface water moving away from the house. The code asks lots to be graded to drain away from foundation walls 1.
- Keep gutters clear and downspouts discharging away from the wall.
- Fix plumbing leaks quickly, because softened soil carries less.
- Avoid heavy new loads near the wall, such as large planters or stored materials, without advice.
- Keep photos and notes of cracks, with dates, so an engineer can read the history.
See drainage and grading for water at the wall.
Signs of a bearing problem, and when to call an engineer
Signs that soil support may be inadequate include a footing or slab that has dropped, new cracks, and doors and windows that stick. These are clues only. Call a licensed structural or geotechnical engineer when you see:
- Movement that is large, growing or changing.
- A wall that bows or a corner that separates.
- Sticking doors and windows along with new cracks.
- Washed-out soil beside a footing.
- Any safety doubt.
Use the structural engineer guide. FEMA says to consult a geotechnical engineer to find whether stronger soils are present to support foundation loads, and a structural engineer should design any underpinning if soil strength is adequate 2.
What the building code says about soil support
IRC R401.2 requires foundations to accommodate loads and transmit them to the supporting soil. It says fill soils that support footings and foundations must be designed, installed and tested under accepted engineering practice 1.
IRC R401.4 and R401.4.1 let a building official require a soil test where soil science data suggest expansive, compressible, shifting or other questionable soils.
In place of a complete geotechnical evaluation, the code lets a presumptive table of load-bearing values be used.
The code’s own footnote says that where weak soils are likely, a soils investigation sets the value 1.
IRC R403.1 says footings shall be supported on undisturbed natural soils or engineered fill, and R403.1.1 bases footing width on the load-bearing value of the soil 1.
These sections are quoted from Seattle’s 2021 residential code, which reproduces the 2021 IRC with city amendments. Editions and local amendments vary, so check the code your jurisdiction adopted. Texas guidance cites the same R401.4 soil test language for the 2015 IRC 6.
Bearing capacity vs. related soil terms
| Term | What it describes | Where it matters |
|---|---|---|
| Bearing capacity | Pressure soil can carry from a footing | Footing size and foundation choice 1 |
| Settlement | How far the soil compresses under load | Cracks and tilt; see foundation settlement |
| Soil consolidation | Slow squeezing out of water from soft soil | Long-term settlement; see soil consolidation |
| Shrink-swell | Volume change with moisture | Seasonal movement 4 |
| Compaction | Density achieved in placed fill | Fill under slabs and footings 5 |
Common myths about soil bearing capacity
- Myth Every soil of one type has the same bearing capacity.
- Reality Moisture, density, depth and fill change it, so a soil name is not a value.
- Myth A code table value is a design for my house.
- Reality It is a presumptive value used when no evaluation is done, and weak soils call for a soils investigation 1.
- Myth If soil is strong, the house cannot settle.
- Reality Settlement and moisture-driven movement are separate from strength 4.
- Myth A bigger footing always fixes it.
- Reality A wider footing lowers pressure but cannot cure fill, expansive clay or poor drainage.
- Myth Bearing capacity is the same as load-bearing wall.
- Reality One describes the ground, the other a wall in the structure.
Where local soils and code adoption change the answer
Bearing capacity is local because soils are local. Places with expansive clay, such as parts of Texas and Colorado, add shrink-swell design on top of strength checks 6.
Cold regions add frost depth to footing depth, as the code requires footings to be protected from frost 1. Coastal and flood-prone areas add scour, which can undermine shallow footings, as FEMA notes 2. Ask your building department which code edition and amendments apply.
When bearing capacity matters, and what to do next
Bearing capacity matters most before building, when planning an addition, and when a house shows movement and the soil under it is unknown. For a new build or addition, the designer needs a soil recommendation. For an older house, an engineer reads movement history and may recommend a geotechnical investigation.
Start by asking for any soil report from the original build, then try the foundation type identifier to be sure what you have. Never choose a repair from a soil name.
- If You are building or adding on
- Then Ask the designer for a soil recommendation or geotechnical report
- If Your house shows new or growing cracks
- Then Record them and call a licensed structural engineer
Questions about Soil Bearing Capacity
What is soil bearing capacity?
It is the pressure the ground under a footing can carry from a building without shearing or settling too far. It depends on the soil, its moisture, the footing size and depth, and how much settlement the structure can tolerate. A site report from a qualified engineer sets the working value.
How is soil bearing capacity determined?
By a geotechnical evaluation with borings or test pits and lab tests, or, for ordinary small houses, by the presumptive table in the model code. The code lets a building official require a soil test where expansive, compressible or questionable soils are likely.
What is the bearing capacity of my soil?
It cannot be answered from a soil name. It depends on your lot’s soil, moisture, fill and footing design, and only a site investigation gives a value. This glossary prints no bearing numbers on purpose, because a number without a report can mislead.
What is the difference between bearing capacity and a load-bearing wall?
Bearing capacity describes the ground under a footing. A load-bearing wall is part of the structure that carries weight from above. They meet at the footing, where the wall’s load passes into the soil.
Does a wider footing increase bearing capacity?
It does not change the soil’s capacity, but it spreads the same load over more area, so the pressure on the soil drops. Footing width in the model code is based on the soil’s load-bearing value. Real sizes come from engineering tables and design.
Can soil moisture change bearing capacity?
Yes. Wet or softened soil often carries less, and moisture changes can also swell or shrink clay. Keeping surface water and leaks away from the foundation helps keep support steady. Local conditions vary, so ask an engineer about your lot.
When does the code require a soils investigation?
The IRC lets a building official require a soil test where expansive, compressible, shifting or other questionable soils are likely, and its table footnote calls for a soils investigation where weak soils are likely. Local amendments differ, so check with your building department.
What if the soil is too weak for shallow footings?
Designers can use a deep foundation to reach stronger soil or bedrock, improve the ground, or replace weak soil with engineered fill. FEMA describes deep foundations as supported by soils or bedrock well below the surface. The choice belongs to a licensed engineer.
Does bearing capacity explain foundation cracks?
Not by itself. Cracks come from movement history, moisture, loads, construction details and site conditions. Weak soil can be one cause, but a crack alone does not show it. A licensed engineer reads the full picture before any diagnosis.
Sources
- City of Seattle, 2021 Seattle Residential Code, Chapter 4 Foundations (2021 IRC text with Seattle amendments), retrieved .
- FEMA, Hurricane and Flood Mitigation Handbook for Public Facilities, Fact Sheet 3.1: Foundations (March 2022), retrieved .
- Penn State, Singh and Scanlon, Concrete in Residential Construction, 1st Residential Building Design and Construction Conference (2013), retrieved .
- USDA NRCS, Technical Guide Section II: Soil Interpretations, Engineering (May 2008), retrieved .
- USDA NRCS, National Engineering Handbook Part 645, Subpart H: Earthfill and Rockfill (amended March 2025), retrieved .
- Texas Dept. of Licensing and Regulation, IHB Technical Bulletin TB 10-01, Foundations on Expansive Soils: Residential (2010, rev. 2018), retrieved .
Expert review
Written by the HyreFoundation Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Code text comes from Seattle’s 2021 residential code, which reproduces the 2021 IRC with city amendments, and a Texas agency bulletin on the 2015 IRC.
Foundation definitions and the geotechnical-engineer advice come from FEMA Fact Sheet 3.1. Shrink-swell classes come from the NRCS Technical Guide. No bearing capacity or design value is stated anywhere on this page, by design. No prices.
Suggest a correction. We fix errors and say what changed.