CHAPTER 5 - FOUNDATION REQUIREMENTS
500. GENERAL. This section outlines
general material and quality standards for all
foundations in this manual.
501. EXCAVATION
501-1. FOOTING DEPTH. Excavation for
footings or foundation walls shall extend below
depth of soil subjected to seasonal or character-
istic volume change to undisturbed soil that
provides adequate bearing. Select the greatest
depth required by any of the provisions below,
reference Figure 5-1.
A. Maximum Frost Penetration Depth.
The bottom of footings shall extend at least to
the depth indicated on the map on page H-4.
B. Alternate Seasonal Wetting and
Drying. This is especially important with ex-
pansive soils. If expansive soils exist, consult
a geotechnical engineer to obtain required foot-
ing depth.
C. Footing Depth. The footings shall be
deep enough to provide required uplift capac-
ity. (This value may need to be determined for
high wind areas after the calculations needed to
determine footing bearing have been com-
pleted.)
502. FOUNDATION MATERIALS.
Footings and foundations shall be constructed
of solid materials such as masonry, concrete, or
treated wood, based on the Foundation Design
Concept Selection (Appendix A) and Founda-
tion Capacity Tables. (Appendix C) (For ma-
sonry and concrete refer to CABO R-302.2,
R-304.1 and R-304.3; for wood refer to CABO
R-302.1 and R-304.5.)
503. STRUCTURAL REQUIRE-
MENTS
503-1. FOUNDATION REQUIREMENTS.
All exterior walls, marriage walls, marriage
wall posts, columns and piers, must be sup-
ported on an acceptable foundation system that
must be of sufficient design to support safely
the loads imposed, as determined from the
character of the soil.
A. Height Above Grade. Foundation
walls shall extend at least 8" above the finished
grade adjacent to the foundation at all points.
See Figure 5-1.
B. Minimum Foundation Wall and
Wall Footing Thickness. For masonry or
concrete construction, the minimum foundation
wall will be 6 inches. The minimum reinforced
concrete footing thickness will be 6 inches or
1-1/2 times the length of the footing projection
from the foundation wall, whichever is greater.
503-2. PIER AND COLUMN FOOTING
REQUIREMENTS. Footings for pier founda-
tions shall be reinforced concrete and should be
placed level on firm undisturbed soil of ade-
quate bearing capacity and below the frost
penetration depth. They can also be placed on
engineered, compacted fill, approved by a li-
censed geotechnical engineer.
A. Unusual Conditions. Where unusual
conditions exist, the spacing of piers and pier
size and the load bearing capacity of the soil
shall be determined specifically for such condi-
tions.
5 - 1
