Presumptive Soil Bearing Values (IBC Table 1806.2)
When a building department does not require a soils report, the International Building Code lets designers use these presumptive values for footings. They are conservative maximums by soil class. A geotechnical investigation can justify higher values, and some soils (organic soils, peat, mud and undocumented fill) cannot use this table at all.
| Class of materials | USCS groups | Allowable vertical foundation pressurepsf | Lateral bearing pressurepsf/ft below natural grade | Coefficient of friction (sliding) | Cohesion (sliding)psf |
|---|---|---|---|---|---|
| 1. Crystalline bedrock | 12000 | 1200 | 0.7 | ||
| 2. Sedimentary and foliated rock | 4000 | 400 | 0.35 | ||
| 3. Sandy gravel and/or gravel | GW, GP | 3000 | 200 | 0.35 | |
| 4. Sand, silty sand, clayey sand, silty gravel and clayey gravel | SW, SP, SM, SC, GM, GC | 2000 | 150 | 0.25 | |
| 5. Clay, sandy clay, silty clay, clayey silt, silt and sandy silt | CL, ML, MH, CH | 1500 | 100 | 130 |
Notes
- Mud, organic silt, organic clays (OL, OH), peat and undocumented fill are not covered and require a geotechnical evaluation.
- The coefficient of friction is multiplied by the dead load. Cohesion is multiplied by the contact area and, per the code footnote, is limited to one-half the dead load.
- Vertical and lateral values may be increased by one-third when used with the alternative allowable stress design load combinations that include wind or earthquake.
- Values apply to soils near the surface. A building official can require a soils investigation where expansive, compressible or shifting soils are suspected.
- A blank cell means the code does not list that resistance for that class.
Frequently asked questions
What soil bearing value can I use without a soils report?
Where the building official allows it, IBC Table 1806.2 gives 1,500 psf for clays and silts, 2,000 psf for sands, 3,000 psf for gravels and higher values for rock. Many residential footings are designed for 1,500 psf for that reason.
Can a soils report allow higher bearing pressure?
Yes. The table values are maximums unless data supporting higher values is submitted and approved, which is normally a geotechnical report.
Does the table apply to fill?
No. Undocumented fill is excluded. Engineered fill placed and tested under a geotechnical engineer's observation can be assigned a value in that engineer's report.
Sources
- International Code Council, 2021 and 2024 International Building Code, Section 1806.2 and Table 1806.2 Presumptive Load-Bearing Values
More reference tables
Have a project? Get a free quote.
Tell us what you need. An engineer licensed in your state replies with scope, fee and schedule.