Footings for precast concrete foundations shall comply with Section R403.4.
TABLE R403.4 MINIMUM DEPTH OF CRUSHED STONE FOOTINGSa (D), (inches)
FIGURE R403.4(1) BASEMENT OR CRAWL SPACE WITH PRECAST FOUNDATION WALL BEARING ON CRUSHED STONE
FIGURE R403.4(2) BASEMENT OR CRAWL SPACE WITH PRECAST FOUNDATION WALL ON SPREAD FOOTING
TABLE R403.4 MINIMUM DEPTH OF CRUSHED STONE FOOTINGSa (D), (inches)
| NUMBER OF STORIES | UNIFORM WALL LOAD | LOAD-BEARING VALUE OF SOIL (psf) | |||||||||||||||
| 1500 | 2000 | 3000 | 4000 | ||||||||||||||
| MH, CH, CL, ML | SC, GC, SM, GM, SP, SW | GP, GW | |||||||||||||||
| Wall width (inches) | Wall width (inches) | Wall width (inches) | Wall width (inches) | ||||||||||||||
| 6 | 8 | 10 | 12 | 6 | 8 | 10 | 12 | 6 | 8 | 10 | 12 | 6 | 8 | 10 | 12 | ||
| Conventional light-frame construction | |||||||||||||||||
| 1-story | 1100 plf | 6 | 4 | 4 | 4 | 6 | 4 | 4 | 4 | 6 | 4 | 4 | 4 | 6 | 4 | 4 | 4 |
| 2-story | 1800 plf | 8 | 6 | 4 | 4 | 6 | 4 | 4 | 4 | 6 | 4 | 4 | 4 | 6 | 4 | 4 | 4 |
| 3-story | 2900 plf | 16 | 14 | 12 | 10 | 10 | 8 | 6 | 6 | 6 | 4 | 4 | 4 | 6 | 4 | 4 | 4 |
| 4-inch brick veneer over light-frame or 8-inch hollow concrete masonry | |||||||||||||||||
| 1-story | 1500 plf | 6 | 4 | 4 | 4 | 6 | 4 | 4 | 4 | 6 | 4 | 4 | 4 | 6 | 4 | 4 | 4 |
| 2-story | 2700 plf | 14 | 12 | 10 | 8 | 10 | 8 | 6 | 4 | 6 | 4 | 4 | 4 | 6 | 4 | 4 | 4 |
| 3-story | 4000 plf | 22 | 22 | 20 | 18 | 16 | 14 | 12 | 10 | 10 | 8 | 6 | 4 | 6 | 4 | 4 | 4 |
| 8-inch solid or fully grouted masonry | |||||||||||||||||
| 1-story | 2000 plf | 10 | 8 | 6 | 4 | 6 | 4 | 4 | 4 | 6 | 4 | 4 | 4 | 6 | 4 | 4 | 4 |
| 2-story | 3600 plf | 20 | 18 | 16 | 16 | 14 | 12 | 10 | 8 | 8 | 6 | 4 | 4 | 6 | 4 | 4 | 4 |
| 3-story | 5300 plf | 32 | 30 | 28 | 26 | 22 | 22 | 20 | 18 | 14 | 12 | 10 | 8 | 10 | 8 | 6 | 4 |
| For SI: 1 inch = 25.4 mm, 1 plf = 14.6 N/m, 1 pound per square foot = 47.9 N/m2. |
| a. Linear interpolation of stone depth between wall widths is permitted within each Load-Bearing Value of Soil (psf). |
FIGURE R403.4(1) BASEMENT OR CRAWL SPACE WITH PRECAST FOUNDATION WALL BEARING ON CRUSHED STONE
FIGURE R403.4(2) BASEMENT OR CRAWL SPACE WITH PRECAST FOUNDATION WALL ON SPREAD FOOTING
Clean crushed stone shall be free from organic, clayey or silty soils. Crushed stone shall be angular in nature and meet ASTM C 33, with the maximum size stone not to exceed 1/2 inch (12.7 mm) and the minimum stone size not to be smaller than 1/16 inch (1.6 mm). Crushed stone footings for precast foundations shall be installed in accordance with Figure R403.4(1) and Table R403.4. Crushed stone footings shall be consolidated using a vibratory plate in a maximum of 8-inch (203 mm) lifts. Crushed stone footings shall be limited to Seismic Design Categories A, B and C.