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 1525, July 5, 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,
f
c
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:
1. Detached one- and two-family dwellings of
				light-frame construction and two stories or less above
grade
				plane
are not required to comply with the provisions of ACI 318,
				Sections 21.12.1 through 21.12.4.
2. Section 21.12.4.4(a) of ACI 318 shall not
				apply.