1. Chapter 33
Foundation Systems

2. Introduction All structures are required to have a foundation
Provides a base to distribute weight onto soil
Must be evenly distributed to prevent it from compressing the soil
Must resist floods, winds, earthquakes, and floodwater debris

3. Soil Considerations Soil texture
Affects ability to resist load of foundation
Bearing capacity must be known
Structures built low bearing capacity soil require footings

4. Soil Considerations (cont’d.)
Compaction methods
Static force
Impact forces
Vibration
Freezing
Foundation should be built to a depth where ground is not subject to freezing
Expansion and shrinking can cause cracking

5. Soil Considerations (cont’d.)
Water content
As soil absorbs water, it expands
Causes foundation to heave
Resisted through proper drainage and reinforcing foundation and floor slab
Radon
Cancer-causing gas
Structures built in areas with high levels must provide protection

6. Types of Foundations Piling foundation system
Beams are placed between vertical supports (i.e., piling) to support structural loads
Steep hillsides
Where structure load exceeds soil bearing capacity
Sites subject to flooding or natural forces that cause large amounts of soil to be removed

8. Types of Foundations (cont’d.)
Continuous or spread foundation
Most common for residential construction
Consists of a footing and wall
Concrete strength must be specified
For areas of soft soil or fill material, reinforcement steel (i.e., rebar) is used

12. Types of Foundations (cont’d.)
Grade beams
Added support for a foundation in unstable soil
Fireplace footings
IRC requires minimum footing 12" deep and extend 6" past fireplace face
Veneer footings
Must be wide enough to provide adequate support

13. Types of Foundations (cont’d.)
Foundation wall
Vertical wall
Extends from top of footing to first-floor level
Usually centered on footing to spread loads
Follow IRC and municipal requirements

14. Types of Foundations (cont’d.)
Additional considerations for the foundation wall
Stem wall construction
Anchor bolts
Termite protection
Wood floor support
Wood floor ventilation and access
Foundation wall insulation and reinforcement

18. Types of Foundations (cont’d.)
Retaining or basement walls
Extends full height between basement floor and main floor level
Primarily made of concrete blocks, poured concrete, or concrete-filled insulated concrete foam blocks
Material used will depend on area trends

19. Types of Foundations (cont’d.)
Additional considerations for retaining or basement walls
Retaining wall reinforcement and anchorage
Moisture protection
Foundation windows
Treated-wood basement walls
Pressure-treated lumber can be used to frame crawl space and basement walls

20. Types of Foundations (cont’d.)
Partial-height retaining walls
When a structure is built on a sloping site, retaining wall will not need to be full height
More problems are encountered

21. Types of Foundations (cont’d.)
Interior load supports
Supported on spot footings or piers
Metal connectors
Used at the foundation level to resist stress from wind and seismic forces

24. Dimensioning Foundation Components