(A) Generally.
(1) The foundation of every permanent structure shall be supported by satisfactory bearing material such as natural deposits of rock, gravel, sand, rock flour (inorganic silt), clay or any combination thereof which does not contain an appreciable amount of organic matter. No foundation of a building shall be placed on fill material unless designed and approved by a professional engineer. All loose or deleterious material shall be removed from the formed area before placing concrete.
(2) Where footings are supported at different levels, or at different levels from footings of adjacent structures, foundation plans shall include vertical sections showing, to true scale, all such variations in grade.
(3) In stepped footings, the angle of slope or depth and location of steps shall be such that the allowable stresses are not exceeded at any section. In stepped footings, the effective cross section in compression shall be limited by the area above the neutral plane. Stepped footings shall be cast as a unit.
(4) No footings or foundation shall be placed on frozen soil.
(5) A total perimeter frost footing is required for all structures, except as listed in division (E).
(Prior Code, § 12-153)
(6) Depth of footing/foundation for additions on existing structures can match existing depth provided the original foundation is at least 24 inches below grade.
(B) Thickness. Footings and foundation walls shall be designed to withstand all vertical and horizontal loads. The following table lists the minimum thickness requirements for masonry, light non-combustible and wood frame structures not over three stories in height where soil conditions do not require special design:
Number of Stories | Thickness of Foundation Walls in Inches | Width of Footing in Inches | Thickness of Footing in Inches | Depth of Foundation and Footing Below Finished Surface in Inches | Rebar | |
Concrete | Unit Masonry
| |||||
1 wood frame | 6 | 8 | 16 | 8 | 36 | 2-#4 |
1 | 8 | 8 | 16 | 8 | 36 | 2-#4 |
2 | 8 | 8 | 20 | 8 | 36 | 2-#4 |
3 | 8 | 12 | 20 | 8 | 36 | 2-#4 |
(Prior Code, § 12-154)
(C) Depth. Foundations and footings, except when founded on rock, and except as otherwise provided in this section, shall be carried down below the frost line. Foundations and footings of light noncombustible and wood frame structures may be carried to the depth designated in the table set forth in division (B) above.
(Prior Code, § 12-155)
(D) Commercial buildings. Footings and foundations for commercial buildings shall be constructed of concrete or masonry materials, designed to support all loads to be imposed upon them, but in no case, not less than as stated in the table set forth in division (B) above.
(Prior Code, § 12-156)
(E) Garages, sheds and carports.
(1) Garages and sheds. Foundations for detached garages and storage sheds shall be determined based on gross square footage of the structure.
(a) Single story buildings (walls not exceeding 10 feet in height):
Size (Square Feet) | Footing Dimension | Floor Thickness |
0 to 200 | No footing or floor is required, but the building is required to be securely fastened down. | |
201 to 450 | 8 x 18-inch concrete with 1-#4 | 4-inch concrete minimum |
450+ | 8 x 36-inch concrete with 1-#4 T&B | 4-inch concrete minimum |
(b) Two-story garages or garages having attic storage over 450 square feet:
1. Garages up to 1,500 square feet cumulative must utilize the footing required for detached accessory structures, or a design submitted stamped by a professional engineer.
2. Garages over 1,501 square feet cumulative must utilize the footing required for 1-story single-family residential structures, or a design submitted stamped by a professional engineer.
(2) Carports. Foundations for detached carports are determined by the support mechanism of the structure.
(a) Four-inch minimum slab only:
1. Can be utilized only on a single-car carport with a maximum size of 12 feet by 20 feet.
2. Can be used only on a single-car carport with a continuous bottom runner of any material allowed by code.
3. Required to be fastened to the slab at 6-foot intervals with a fastener within 12 inches of each end. Fasteners are required to be 1/2-inch wedge type, penetrating a minimum of 3 inches into the concrete slab.
(b) Post hole type footing:
1. Direct bury of the post a minimum of 34 inches with a concrete block a minimum of 12 inches round by 2 inches depth placed beneath the post, or poured.
2. a. The post can be any material allowed by code; or
b. Poured footing 12 inches round by 36 inches deep with the post mechanically fastened to the concrete footing.
3. No floor is required for this structure.
(c) Garage and shed footings:
1. A carport can utilize any footing type listed above for garages and sheds.
2. A carport can utilize any footing type listed for residential construction.
3. No floor is required for this structure. Note: If the intent for the carport is that someday it will be enclosed and utilized as a garage, the foundations as listed above for garages and sheds should be used.
(3) Patio covers. Foundations for patio covers are determined by the support mechanism of the structure and whether the structure is attached or detached to the main structure.
(a) Unenclosed patio covers:
1. Direct bury of the post a minimum of 34 inches with a precast concrete block a minimum of 12 inches round by 2 inches depth placed beneath the post.
2. a. The post can be any material allowed by code; or
b. Poured footing 12 inches round by 36 inches deep with the post mechanically fastened to the concrete footing.
3. A patio cover can utilize any footing type listed for residential construction.
(b) Enclosed patio cover: Must utilize the foundation type listed for single-family residential construction.
(4) Building setbacks and separation requirements. All garages, sheds and carports must meet all building setbacks (front, side and rear) and separation requirements from other buildings/structures pursuant to Chapters 150 and 156 of this code.
(Prior Code, § 12-157)
(Ord. 3035, § 1, 9-5-1995; Am. Ord. 4042, passed 11-3-2020)