Chapter 4
Footing: A horizontal structural element designed to transfer the structure load to the ground. There are four main types of footings: Spread, Strip, Raft, and Pile.
Foundation: Vertical base structures that support the building above and transfer loads to the ground. These structural support walls often have footings at the bottom of the wall where the wall would contact the ground. Foundation walls use concrete, masonry, wood, stone and other suitable materials. One exception is the slab on grade, which is a horizontal foundation type.
Soils: All structures must rest on the ground. Understanding the mechanical properties of the soils is important. A geotechnical evaluation of the site may be necessary to establish local soil characteristics. The architect and structural engineer utilize the geotechnical report in their design.
| Class of Material | Load-Bearing Pressure |
| Crystalline bedrock | 12,000 psf |
| Sedimentary and foliated rock | 4,000 psf |
| Sandy gravel and/or gravel (GW and GP) | 3,000 psf |
| Sand, silty sand, clayey sand, silty gravel and clayey gravel (SW,SP, SM, SC, GM, AND GC) | 2,000 psf |
| Clay, sandy, silty clay, clayey silt, silt and sandy siltclay (CL, ML, MH and CH) | 1,500 psf |
James St. John, CC BY 2.0 https://creativecommons.org/licenses/by/2.0, via Wikimedia Commons
How footings work
Footing Materials
Footing Illustrations