International Building Code Section 1812


International Building Code 1812.1

General. Isolated and multiple piers used as foundations
shall conform to the requirements of Sections 1812.2
through 1812.10, as well as the applicable provisions of Section
1808.2.

International Building Code 1812.10

Dewatering. Where piers are carried to depths below
water level, the piers shall be constructed by a method that will
provide accurate preparation and inspection of the bottom, and
the depositing or construction of sound concrete or other
masonry in the dry.
2006 INTERNATIONAL BUILDING CODE 371
SOILS AND FOUNDATIONS
372 2006 INTERNATIONAL BUILDING CODE

International Building Code 1812.2

Lateral dimensions and height. The minimum dimension
of isolated piers used as foundations shall be 2 feet (610
mm), and the height shall not exceed 12 times the least horizontal
dimension.

International Building Code 1812.3

Materials. Concrete shall have a 28-day specified compressive
strength (f c) of not less than 2,500 psi (17.24 MPa).
Where concrete is placed through a funnel hopper at the top of
the pier, 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 6 inches (152
mm). Where concrete is to be pumped, the mix design including
slump shall be adjusted to produce a pumpable concrete.

International Building Code 1812.4

Reinforcement. Except for steel dowels embedded 5
feet (1524 mm) or less in the pier, reinforcement where
required shall be assembled and tied together and shall be
placed in the pier hole as a unit before the reinforced portion of
the pier is filled with concrete.
Exception: Reinforcement is permitted to be wet set and the
21/2- inch (64 mm) concrete cover requirement be reduced to
2 inches (51 mm) for Group R-3 and U occupancies not
exceeding two stories of light-frame construction, provided
the construction method can be demonstrated to the satisfaction
of the building official.
Reinforcement shall conform to the requirements of Sections
1810.1.2.1 and 1810.1.2.2.
Exceptions:
1. Isolated piers supporting posts of Group R-3 and U
occupancies not exceeding two stories of light-frame
construction are permitted to be reinforced as
required by rational analysis but not less than a minimum
of one No. 4 bar, without ties or spirals, when
detailed so the pier is not subject to lateral loads and
the soil is determined to be of adequate stiffness.
2. Isolated piers supporting posts and bracing from
decks and patios appurtenant to Group R-3 and U
occupancies not exceeding two stories of light-frame
construction are permitted to be reinforced as
required by rational analysis but not less than one No.
4 bar, without ties or spirals, when the lateral load, E,
to the top of the pier does not exceed 200 pounds (890
N) and the soil is determined to be of adequate stiffness.
3. Piers supporting the concrete foundation wall of
Group R-3 and U occupancies not exceeding two stories
of light-frame construction are permitted to be
reinforced as required by rational analysis but not less
than two No. 4 bars, without ties or spirals, when it
can be shown the concrete pier will not rupture when
designed for the maximum seismic load, Em, and the
soil is determined to be of adequate stiffness.
4. Closed ties or spirals where required by Section
1810.1.2.2 are permitted to be limited to the top 3 feet
(914 mm) of the piers 10 feet (3048 mm) or less in
depth supporting Group R-3 and U occupancies of
Seismic Design Category D, not exceeding two stories
of light-frame construction.

International Building Code 1812.5

Concrete placement. Concrete shall be placed in such
a manner as to ensure the exclusion of any foreign matter and to
secure a full-sized shaft. 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.
370 2006 INTERNATIONAL BUILDING CODE
SOILS AND FOUNDATIONS

International Building Code 1812.6

Belled bottoms. Where pier foundations are belled at
the bottom, the edge thickness of the bell shall not be less than
that required for the edge of footings. Where the sides of the
bell slope at an angle less than 60 degrees (1 rad) from the horizontal,
the effects of vertical shear shall be considered.

International Building Code 1812.7

Masonry. Where the unsupported height of foundation
piers exceeds six times the least dimension, the allowable
working stress on piers of unit masonry shall be reduced in
accordance with ACI 530/ASCE 5/TMS 402.

International Building Code 1812.8

Concrete. Where adequate lateral support is not provided,
and the unsupported height to least lateral dimension
does not exceed three, piers of plain concrete shall be designed
and constructed as pilasters in accordance with ACI 318.
Where the unsupported height to least lateral 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 furnished by
the surrounding materials as defined in Section 1808.2.9,
piers are permitted to be constructed of plain or reinforced
concrete. The requirements of ACI 318 for bearing on concrete
shall apply.

International Building Code 1812.9

Steel shell. Where concrete piers are entirely encased
with 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 1808.2.17. Horizontal joints in
the shell shall be spliced to comply with Section 1808.2.7.