// CODE SNIPPET
1805.5 Shallow Foundations
JUMP TO FULL CODE CHAPTER
Shallow foundations shall be designed and constructed in accordance with Sections 1805.5.1 through 1805.5.6.
Shallow foundations shall be designed so that the allowable bearing capacity of the soil is not exceeded, and that differential settlements are within the allowable limits for the structure. The minimum width of shallow foundations shall be 18 inches (457 mm).
Shallow foundations shall be designed for the most unfavorable effects due to the combinations of loads specified in Section 1605.3. The dead load shall include the weight of shallow foundations and overlying fill. Reduced live loads, as specified in Section 1607.9, are permitted to be used in the design of shallow foundations.
Where machinery operations or other vibrations are transmitted through the shallow foundations, consideration shall be given in the shallow foundation design to prevent detrimental disturbances of the soil.
When the possibility of shifting or moving soil exists, the short and long term impact of such soils shall be considered in the design of shallow foundations.
The design, materials and construction of concrete shallow foundations shall comply with Sections 1805.5.2.1 through 1805.5.2.5 and the provisions of Chapter 19.
Concrete in shallow foundations shall have a specified compressive strength (f'c) of not less than 2,500 pounds per square inch (psi) (17 237 kPa) at 28 days.
Where a structure is assigned to Seismic Design Category D in accordance with Section 1613, individual spread footings founded on soil defined in Section 1613.5.2 as Site Class E or F shall be interconnected by ties. Ties shall be capable of carrying, in tension or compression, a force equal to the product of the larger footing load times the seismic coefficient SDS divided by 10 unless it is demonstrated that equivalent restraint is provided by reinforced concrete beams within slabs on grade or reinforced concrete slabs on grade.
The thickness of plain concrete footings supporting walls of other than light-frame construction shall not be less than 8 inches (203 mm) where placed on soil.
Exception: For plain concrete footings supporting Group R-3 occupancies, the thickness is permitted to be 6 inches (152 mm), provided that the footing does not extend beyond a distance greater than the thickness of the footing on either side of the supported wall.
Exception: For plain concrete footings supporting Group R-3 occupancies, the thickness is permitted to be 6 inches (152 mm), provided that the footing does not extend beyond a distance greater than the thickness of the footing on either side of the supported wall.
Concrete shallow foundations shall not be placed through water unless a tremie or other method approved by the commissioner is used. Where placed under or in the presence of water, the concrete shall be deposited by approved means to ensure minimum segregation of the mix and negligible turbulence of the water.
No shallow foundation shall be placed on frozen soils unless the soils are maintained in frozen condition throughout the service life of the structure being supported. No foundation shall be placed in freezing weather unless provision is made to maintain the underlying soil free of frost. Concrete shallow foundations shall be protected from freezing during depositing and for a period of not less than five days thereafter. Water shall not be allowed to flow through the deposited concrete.
The design, materials and construction of masonry-unit footings shall comply with the provisions of Chapter 21.
Grillage footings of structural steel shapes shall be separated with approved steel spacers and be entirely encased in concrete with at least 6 inches (152 mm) on the bottom and at least 4 inches (102 mm) at all other points. The spaces between the shapes shall be completely filled with concrete or cement grout.
Refer to Chapter 23.
Refer to Chapter 23.
The design, materials, and construction of pier foundations shall conform to the requirements of Sections 1805.5.2, 1805.5.3, and 1805.5.7.1 through 1805.5.7.6.
Exception: Piers shall be load tested as a deep foundation in accordance with the applicable portions of Section 1808 when the bearing stratum is not physically available for inspection during construction as required by Chapter 17.
Exception: Piers shall be load tested as a deep foundation in accordance with the applicable portions of Section 1808 when the bearing stratum is not physically available for inspection during construction as required by Chapter 17.
The minimum horizontal dimension of piers shall be 2 feet (610 mm), and the height shall not exceed 12 times the least horizontal dimension.
Where adequate lateral support is furnished by the surrounding materials defined in Section 1808.7, piers may be constructed of plain or reinforced concrete and the requirements of ACI 318 shall apply.
Exception: Where adequate lateral support is not provided, and the ratio of unsupported height to least horizontal dimension does not exceed three, piers of plain concrete shall be designed and constructed as pedestals in accordance with ACI 318. Where the unsupported height to least horizontal dimension exceeds three, piers shall be constructed of reinforced concrete, and shall conform to the requirements for columns in ACI 318.
Exception: Where adequate lateral support is not provided, and the ratio of unsupported height to least horizontal dimension does not exceed three, piers of plain concrete shall be designed and constructed as pedestals in accordance with ACI 318. Where the unsupported height to least horizontal dimension exceeds three, piers shall be constructed of reinforced concrete, and shall conform to the requirements for columns in ACI 318.
Reinforcement shall be tied and placed as a unit in the pier prior to placement of concrete.
Exception: Steel dowels embedded 5 feet (1524 mm) or less in the pier may be placed individually. Reinforcement is permitted to be wet set and the concrete cover that is otherwise required to measure a minimum of 21/2 inches (64 mm) may be reduced to 2 inches (51 mm) for Groups R-3 and U occupancies not exceeding two stories of light-frame construction, provided the construction method is approved by the commissioner.
Exception: Steel dowels embedded 5 feet (1524 mm) or less in the pier may be placed individually. Reinforcement is permitted to be wet set and the concrete cover that is otherwise required to measure a minimum of 21/2 inches (64 mm) may be reduced to 2 inches (51 mm) for Groups R-3 and U occupancies not exceeding two stories of light-frame construction, provided the construction method is approved by the commissioner.
Concrete shall be placed in such a manner as to ensure the exclusion of any foreign matter and to fill the full lateral dimensions of each pier. Concrete shall not be placed through water except where a tremie or other approved method is used. When depositing concrete from the top of the pier, the concrete shall not be chuted directly into the pier but shall be poured in a rapid and continuous operation through a funnel hopper centered at the top of the pier.
Where concrete piers are entirely encased within a circular steel shell, and the area of the shell steel is considered reinforcing steel, the steel shall be protected under the conditions specified in Section 1808.2.12. Horizontal joints in the shell shall be spliced to comply with Section 1808.2.11.
Where piers are carried to depths below the groundwater level, the piers shall be constructed by a method that will provide accurate preparation and inspection of the subgrade in dry conditions.
Concrete and masonry foundation walls shall be designed in accordance with Chapter 19 or 21, respectively.
The minimum thickness of concrete and masonry foundation walls shall comply with Section 1805.5.8.1.1.
Related Code Sections
Section 1805 Soils and Foundations, Shallow Foundations
Shallow foundations shall be designed and constructed in accordance with Sections 1805.1 through 1805.9. Shallow foundations shall be constructed ...
1805.5.2.3 Soils and Foundations, Plain Concrete Footings
The thickness of plain concrete footings supporting walls of other than light-frame construction shall not be less than 8 inches (203 mm) where placed ...
NYC Building Code 2014 > 18 Soils and Foundations > 1805 Shallow Foundations > 1805.5 Shallow Foundations > 1805.5.2 Concrete Shallow Foundations > 1805.5.2.3 Plain Concrete Footings
1805.5.2.4 Soils and Foundations, Placement of Concrete
Concrete shallow foundations shall not be placed through water unless a tremie or other method approved by the commissioner is used. Where placed ...
NYC Building Code 2014 > 18 Soils and Foundations > 1805 Shallow Foundations > 1805.5 Shallow Foundations > 1805.5.2 Concrete Shallow Foundations > 1805.5.2.4 Placement of Concrete
1805.5.2.5 Soils and Foundations, Protection of Concrete
No shallow foundation shall be placed on frozen soils unless the soils are maintained in frozen condition throughout the service life ...
NYC Building Code 2014 > 18 Soils and Foundations > 1805 Shallow Foundations > 1805.5 Shallow Foundations > 1805.5.2 Concrete Shallow Foundations > 1805.5.2.5 Protection of Concrete