Code of Massachusetts Regulations
780 CMR - STATE BOARD OF BUILDING REGULATIONS AND STANDARDS
Chapter 18 - Soils and Foundations
Section 1808 - FOUNDATIONS
Subsection 1808.8 - Concrete foundations
Current through Register 1531, September 27, 2024
The design, materials and construction of concrete foundations shall comply with Sections 1808.8.1 through 1808.8.6 and the provisions of Chapter 19.
Exception: Where concrete footings supporting walls of light-frame construction are designed in accordance with Table 1809.7, a specific design in accordance with Chapter 19 is not required.
1808.8.1 Concrete or grout strength and mix proportioning. Concrete or grout in foundations shall have a specified compressive strength (f c) not less than the largest applicable value indicated in Table 1808.8.1.
Where concrete is placed through a funnel hopper at the top of a deep foundation element, the concrete mix shall be designed and proportioned so as to produce a cohesive workable mix having a slump of not less than 4 inches (102 mm) and not more than 8 inches (204 mm). Where concrete or grout is to be pumped, the mix design including slump shall be adjusted to produce a pumpable mixture.
TABLE 1808.8.1 MINIMUM SPECIFIED COMPRESSIVE STRENGTH f C OF CONCRETE OR GROUT
| FOUNDATION ELEMENT OR CONDITION | SPECIFIED COMPRESSIVE STRENGTH,fc |
| 1. Foundations for structures assigned to Seismic Design Category A, B or C | 2,500 psi |
| 2a. Foundations for Group R or U occupancies of
light-frame construction, two stories or less in height, assigned to Seismic Design Category D, E or F |
2,500 psi |
| 2b. Foundations for other structures assigned to Seismic Design Category D, E or F | 3,000 psi |
| 3. Precast nonprestressed driven piles | 4,000 psi |
| 4. Socketed drilled shafts | 4,000 psi |
| 5. Micropiles | 4,000 psi |
| 6. Precast prestressed driven piles | 5,000 psi |
| For SI: 1 pound per square inch = 0.00689 MPa. |
1808.8.2 Concrete cover. The concrete cover provided for prestressed and nonprestressed reinforcement in foundations shall be no less than the largest applicable value specified in Table 1808.8.2. Longitudinal bars spaced less than 11/2 inches (38 mm) clear distance apart shall be considered bundled bars for which the concrete cover provided shall also be no less than that required by Section 7.7.4 of ACI 318. Concrete cover shall be measured from the concrete surface to the outermost surface of the steel to which the cover requirement applies. Where concrete is placed in a temporary or permanent casing or a mandrel, the inside face of the casing or mandrel shall be considered the concrete surface.
TABLE 1808.8.2 MINIMUM CONCRETE COVER
| FOUNDATION ELEMENT OR CONDITION | MINIMUM COVER | |
| 1. Shallow foundations | In accordance withSection7.7 of ACI 318 | |
| 2. Precast nonprestressed deep foundation elements |
3 inches 2 inches In accordance with Section7.7.3 of ACI 318 |
|
| Exposed to seawater Not manufactured under plant conditions Manufactured under plant control conditions |
||
| 3. Precast prestressed deep foundation elements |
2.5 inches In accordance with Section7.7.3 of ACI 318 |
|
| Exposed to seawater Other |
||
| 4. Cast-in-place deep foundation elements not enclosed by a steel pipe, tube or permanent casing | 2.5 inches | |
| 5. Cast-in-place deep foundation elements enclosed by a steel pipe, tube or permanent casing | 1 inch | |
| 6. Structural steel core within a steel pipe, tube or permanent casing | 2 inches | |
| 7. Cast-in-place drilled shafts enclosed by a stable rock socket | 1.5 inches | |
| For SI: 1 inch = 25.4 mm. |
1808.8.3 Placement of concrete. Concrete shall be placed in such a manner as to ensure the exclusion of any foreign matter and to secure a full-size foundation. Concrete shall not be placed through water unless a tremie or other method approved by the building official 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. Where depositing concrete from the top of a deep foundation element, the concrete shall be chuted directly into smooth-sided pipes or tubes or placed in a rapid and continuous operation through a funnel hopper centered at the top of the element.
1808.8.4 Protection of concrete. Concrete 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.
1808.8.5 Forming of concrete. Concrete foundations are permitted to be cast against the earth where, in the opinion of the building official, soil conditions do not require formwork. Where formwork is required, it shall be in accordance with Chapter 6 of ACI 318.
1808.8.6 Seismic requirements. See Section 1908 for additional requirements for foundations of structures assigned to Seismic Design Category C, D, E or F.
For structures assigned to Seismic Design Category D, E or F, provisions of ACI 318, Sections 21.12.1 through 21.12.4, shall apply where not in conflict with the provisions of Sections 1808 through 1810.
Exceptions:
