1. Foundation Systems

2. Standard ACT-ADDI-6 Students will prepare foundation plans.
Explain the purpose of foundation plans.
Identify different foundation systems and terminology.
Draw and dimension foundation plans.

3. Purpose
To provide a base to distribute the weight of the structure onto the soil
It must be evenly distributed over a large enough area to prevent compression of the soil
Must resist floods, winds, and earthquakes
Floods can wash away supporting soil
Wind pushes against houses, pushing them up
Must move with the ground in an earthquake

4. Soil Considerations
Bearing capacity of soil must be known before foundation can be designed
Bearing capacity: amount of weight a square foot of soil can support
Freezing – foundation should be built below freezing level
In Georgia – under 10”
In Minnesota – up to 100”!
Water content – soil will expand and contract with water

5. Types of Foundations Pilings Continuous (Spread) Foundations
Grade Beam

6. Piling Foundation System
Uses beams placed between vertical supports (piling) to support structural loads
When structural load exceeds bearing capacity of soil
Used on steep hillsides
Site subject to flooding
Pilings are typically made of concrete with steel reinforcement
Where load imposed by the structure exceeds the bearing capacity of the soil
On steep hillside sites where it may not be feasible to use traditional excavating equipment
On sites subject to flooding or other natural forces that might cause large amounts of soil to be removed (coastal property and sites near inland bodies of water)

7. Continuous Foundation
Most common in residential construction
Consists of a footing and wall
Footing: base of the foundation system; made of poured concrete
Footing can be bonded to the foundation wall with a key or with steel
- Footing: placed so it extends below freezing level; size of footing based on soil-bearing value and the load to be supported
Keyway: place a 2 x 4 in the top of the concrete footing while the concrete is still wet, once concrete has set 2 x 4 is removed then keyway is left in concrete; when concrete wall is poured it will form a key by filling in the keyway
Steel: stronger bond, steel used to tie the footing to the foundation wall

8. Grade Beam Foundation Provides added support
Grade beam is placed under the soil below the stem wall and spans between stable supports
- Stable supports may either be a piling or stable soil
- Depth and reinforcing required for a grade beam are determined by the load to be supported

9. Fireplace Footing
Masonry fireplace will need to be supported by a footing
12” deep footing that extends 6” past the fireplace on each side

10. Veneer Footings
An extension of the footing and must be wide enough to provide support for the veneer

11. Foundation Wall
Vertical wall that extends from the footing to the first floor
Centered on the footing to help evenly spread the load
Height of the wall must extend 6” above the ground

12. Retaining/Basement Wall
Walls that extend full height between the basement floor and main floor level
Basement walls made of poured concrete or concrete blocks (or wood, depending on the building trends of your area)
Used on sloped lots

13. Interior Supports
Spot footings – also known as piers – match the depth of footings

14. Pedestals A column built on top of a footing
Used when upper soils are unstable

15. Metal Connectors
Used to anchor the house to the foundation

16. On Grade Foundations
Slab