International Building Code Section 2109 – International Building Code 2006 Discussions

International Building Code 2109.1

General. Empirically designed masonry shall conform
to this chapter or Chapter 5 of ACI 530/ASCE 5/TMS 402.

Limitations. The use of empirical design of
masonry shall be limited as follows:
1. Empirical design shall not be used for buildings
assigned to Seismic Design Category D, E or F as
specified in Section 1613, nor for the design of the
seismic-force-resisting system for buildings assigned
to Seismic Design Category B or C.
2. Empirical design shall not be used for masonry elements
that are part of the lateral-force-resisting system
where the basic wind speed exceeds 110 mph (79
m/s).
3. Empirical design shall not be used for interior
masonry elements that are not part of the lateralforce-
resisting system in buildings other than
enclosed buildings as defined in Chapter 6 of ASCE 7
in:
3.1. Buildings over 180 feet (55 100 mm) in
height.
3.2. Buildings over 60 feet (18 400 mm) in height
where the basic wind speed exceeds 90 mph
(40 m/s).
3.3. Buildings over 35 feet (10 700 mm) in height
where the basic wind speed exceeds 100 mph
(45 m/s).
3.4. Where the basic wind speed exceeds 110 mph
(79 m/s).
4. Empirical design shall not be used for exterior
masonry elements that are not part of the lateralforce-
resisting system and that are more than 35 feet
(10 700 mm) above ground:
4.1. Buildings over 180 feet (55 100 mm) in
height.
4.2. Buildings over 60 feet (18 400 mm) in height
where the basic wind speed exceeds 90 mph
(40 m/s).
4.3. Buildings over 35 feet (10 700 mm) in height
where the basic wind speed exceeds 100 mph
(45 m/s).
5. Empirical design shall not be used for exterior
masonry elements that are less than or equal to 35 feet
(10 700 mm) above ground where the basic wind
speed exceeds 110 mph (79 m/s).
6. Empirical design shall only be used when the resultant
of gravity loads is within the center third of the
wall thickness and within the central area bounded by
lines at one-third of each cross-sectional dimension of
foundation piers.
7. Empirical design shall not be used forAACmasonry.
In buildings that exceed one or more of the above limitations,
masonry shall be designed in accordance with the
engineered design provisions of Section 2107 or 2108 or the
foundation wall provisions of Section 1805.5.

International Building Code 2109.1.1

International Building Code 2109.2

Lateral stability.

Shear walls. Where the structure depends upon
masonry walls for lateral stability, shear walls shall be provided
parallel to the direction of the lateral forces resisted.

Cumulative length of shear walls. In each
direction in which shearwalls are required for lateral stability,
shear walls shall be positioned in two separate
planes. The minimum cumulative length of shear walls
provided shall be 0.4 times the long dimension of the
building. Cumulative length of shear walls shall not
include openings or any element with a length that is less
than one-half its height.

Maximumdiaphragm ratio. Masonry shear
walls shall be spaced so that the length-to-width ratio of
each diaphragm transferring lateral forces to the shear
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walls does not exceed the values given in Table
2109.2.1.2.

Roofs. The roof construction shall be designed
so as not to impart out-of-plane lateral thrust to the walls
under roof gravity load.

Surface-bonded walls. Dry-stacked, surface-
bonded concrete masonrywalls shall complywith the
requirements of this code for masonry wall construction,
except where otherwise noted in this section.

Strength. Dry-stacked, surface-bonded
concrete masonry walls shall be of adequate strength
and proportions to support all superimposed loadswithout
exceeding the allowable stresses listed in Table
2109.2.3.1. Allowable stresses not specified in Table
2109.2.3.1 shall comply with the requirements of ACI
530/ASCE 5/TMS 402.

Construction. Construction of drystacked,
surface-bonded masonry walls, including
stacking and leveling of units, mixing and application
of mortar and curing and protection shall comply with
ASTM C 946.

International Building Code 2109.2.1

Shear walls. Where the structure depends upon
masonry walls for lateral stability, shear walls shall be provided
parallel to the direction of the lateral forces resisted.

International Building Code 2109.2.1.1

International Building Code 2109.2.1.2

International Building Code 2109.2.2

Roofs. The roof construction shall be designed
so as not to impart out-of-plane lateral thrust to the walls
under roof gravity load.

International Building Code 2109.2.3

Surface-bonded walls. Dry-stacked, surface-
bonded concrete masonrywalls shall complywith the
requirements of this code for masonry wall construction,
except where otherwise noted in this section.

International Building Code 2109.2.3.1

International Building Code 2109.2.3.2

International Building Code 2109.3

Compressive stress requirements.

Calculations. Compressive stresses in masonry
due to vertical dead plus live loads, excluding wind or seismic
loads, shall be determined in accordance with Section
2109.3.2.1. Dead and live loads shall be in accordance
with Chapter 16, with live load reductions as permitted in
Section 1607.9.

Allowable compressive stresses. The compressive
stresses in masonry shall not exceed the values given
in Table 2109.3.2. Stress shall be calculated based on specified
rather than nominal dimensions.

Calculated compressive stresses. Calculated
compressive stresses for single wythe walls and
formultiwythe composite masonrywalls shall be determined
by dividing the design load by the gross
cross-sectional area of the member. The area of openings,
chases or recesses in walls shall not be included in
the gross cross-sectional area of the wall.

Multiwythe walls. The allowable stress
shall be as given in Table 2109.3.2 for theweakest combination
of the units used in each wythe.

International Building Code 2109.3.1

International Building Code 2109.3.2

Allowable compressive stresses. The compressive
stresses in masonry shall not exceed the values given
in Table 2109.3.2. Stress shall be calculated based on specified
rather than nominal dimensions.

Multiwythe walls. The allowable stress
shall be as given in Table 2109.3.2 for theweakest combination
of the units used in each wythe.

International Building Code 2109.3.2.1

International Building Code 2109.3.2.2

Multiwythe walls. The allowable stress
shall be as given in Table 2109.3.2 for theweakest combination
of the units used in each wythe.

International Building Code 2109.4

Lateral support.

Intervals. Masonry walls shall be laterally supported
in either the horizontal or vertical direction at intervals
not exceeding those given in Table 2109.4.1.

Thickness. Except for cavity walls and cantilever
walls, the thickness of a wall shall be its nominal thickness
measured perpendicular to the face of the wall. For cavity
walls, the thickness shall be determined as the sum of the
nominal thicknesses of the individual wythes. For cantilever
walls, except for parapets, the ratio of height-to-nominal
thickness shall not exceed 6 for solid masonry or 4 for hollow
masonry. For parapets, see Section 2109.5.4.

Support elements. Lateral support shall be provided
by crosswalls, pilasters, buttresses or structural frame
members when the limiting distance is taken horizontally, or
by floors, roofs acting as diaphragms or structural frame
members when the limiting distance is taken vertically.

International Building Code 2109.4.1

Intervals. Masonry walls shall be laterally supported
in either the horizontal or vertical direction at intervals
not exceeding those given in Table 2109.4.1.

International Building Code 2109.4.2

International Building Code 2109.4.3

International Building Code 2109.5

Thickness of masonry. Minimum thickness requirements
shall be based on nominal dimensions of masonry.

Thickness of walls. The thickness of masonry
walls shall conform to the requirements of Section 2109.5.

Minimum thickness.

Bearing walls. The minimum thickness of
masonry bearing walls more than one story high shall be
8 inches (203 mm). Bearing walls of one-story buildings
shall not be less than 6 inches (152 mm) thick.

Rubble stone walls. The minimum thickness
of rough, random or coursed rubble stone walls shall be
16 inches (406 mm).

Shear walls. The minimum thickness of
masonry shear walls shall be 8 inches (203 mm).

Foundation walls. The minimum thickness
of foundation walls shall be 8 inches (203 mm) and as
required by Section 2109.5.3.1.
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Foundation piers. The minimum thickness
of foundation piers shall be 8 inches (203 mm).

Parapet walls. The minimum thickness of
parapet walls shall be 8 inches (203 mm) and as required
by Section 2109.5.4.1.

Change in thickness. Where walls of
masonry of hollow units or masonry bonded hollow
walls are decreased in thickness, a course or courses of
solid masonry shall be interposed between the wall
belowand the thinner wall above, or special units or construction
shall be used to transmit the loads from face
shells or wythes above to those below.

Foundation walls. Foundationwalls shall comply
with the requirements of Section 2109.5.3.1 or 2109.5.3.2.

Minimum thickness. Minimum thickness
for foundation walls shall comply with the requirements
of Table 2109.5.3.1. The provisions of Table 2109.5.3.1
are only applicable where the following conditions are
met:
1. The foundation wall does not exceed 8 feet (2438
mm) in height between lateral supports;
2. The terrain surrounding foundation walls is graded
to drain surface water away from foundation
walls;
3. Backfill is drained to remove ground water away
from foundation walls;
4. Lateral support is provided at the top of foundation
walls prior to backfilling;
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5. The length of foundation walls between perpendicular
masonry walls or pilasters is a maximum of
three times the basement wall height;
6. The backfill is granular and soil conditions in the
area are nonexpansive; and
7. Masonry is laid in running bond using TypeMor S
mortar.

Design requirements. Where the requirements
of Section 2109.5.3.1 are not met, foundation
walls shall be designed in accordance with Section
1805.5.

Parapet walls.

Minimum thickness. The minimum thickness
of unreinforced masonry parapets shall meet Section
2109.5.2.6 and their height shall not exceed three
times their thickness.

Additional provisions. Additional provisions
for parapet walls are contained in Sections 1503.2
and 1503.3.

International Building Code 2109.5.1

Thickness of walls. The thickness of masonry
walls shall conform to the requirements of Section 2109.5.

International Building Code 2109.5.2

Minimum thickness.

Bearing walls. The minimum thickness of
masonry bearing walls more than one story high shall be
8 inches (203 mm). Bearing walls of one-story buildings
shall not be less than 6 inches (152 mm) thick.

Rubble stone walls. The minimum thickness
of rough, random or coursed rubble stone walls shall be
16 inches (406 mm).

Shear walls. The minimum thickness of
masonry shear walls shall be 8 inches (203 mm).

Foundation walls. The minimum thickness
of foundation walls shall be 8 inches (203 mm) and as
required by Section 2109.5.3.1.
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Foundation piers. The minimum thickness
of foundation piers shall be 8 inches (203 mm).

Parapet walls. The minimum thickness of
parapet walls shall be 8 inches (203 mm) and as required
by Section 2109.5.4.1.

International Building Code 2109.5.2.1

Bearing walls. The minimum thickness of
masonry bearing walls more than one story high shall be
8 inches (203 mm). Bearing walls of one-story buildings
shall not be less than 6 inches (152 mm) thick.

International Building Code 2109.5.2.2

Rubble stone walls. The minimum thickness
of rough, random or coursed rubble stone walls shall be
16 inches (406 mm).

International Building Code 2109.5.2.3

Shear walls. The minimum thickness of
masonry shear walls shall be 8 inches (203 mm).

International Building Code 2109.5.2.4

Foundation walls. The minimum thickness
of foundation walls shall be 8 inches (203 mm) and as
required by Section 2109.5.3.1.
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International Building Code 2109.5.2.5

Foundation piers. The minimum thickness
of foundation piers shall be 8 inches (203 mm).

International Building Code 2109.5.2.6

Parapet walls. The minimum thickness of
parapet walls shall be 8 inches (203 mm) and as required
by Section 2109.5.4.1.

International Building Code 2109.5.2.7

International Building Code 2109.5.3

Foundation walls. Foundationwalls shall comply
with the requirements of Section 2109.5.3.1 or 2109.5.3.2.

Design requirements. Where the requirements
of Section 2109.5.3.1 are not met, foundation
walls shall be designed in accordance with Section
1805.5.

International Building Code 2109.5.3.1

International Building Code 2109.5.3.2

Design requirements. Where the requirements
of Section 2109.5.3.1 are not met, foundation
walls shall be designed in accordance with Section
1805.5.

International Building Code 2109.5.4

Parapet walls.

Minimum thickness. The minimum thickness
of unreinforced masonry parapets shall meet Section
2109.5.2.6 and their height shall not exceed three
times their thickness.

Additional provisions. Additional provisions
for parapet walls are contained in Sections 1503.2
and 1503.3.

International Building Code 2109.5.4.1

Minimum thickness. The minimum thickness
of unreinforced masonry parapets shall meet Section
2109.5.2.6 and their height shall not exceed three
times their thickness.

International Building Code 2109.5.4.2

Additional provisions. Additional provisions
for parapet walls are contained in Sections 1503.2
and 1503.3.

International Building Code 2109.6

Bond.

General. The facing and backing of multiwythe
masonry walls shall be bonded in accordance with Section
2109.6.2, 2109.6.3 or 2109.6.4.

Bonding with masonry headers.

Solid units. Where the facing and backing
(adjacent wythes) of solid masonry construction are
bonded by means of masonry headers, no less than 4 percent
of thewall surface of each face shall be composed of
headers extending not less than 3 inches (76 mm) into the
backing. The distance between adjacent full-length
headers shall not exceed 24 inches (610 mm) either vertically
or horizontally. In walls in which a single header
does not extend through thewall, headers from the opposite
sides shall overlap at least 3 inches (76 mm), or headers
from opposite sides shall be covered with another
header course overlapping the header below at least 3
inches (76 mm).

Hollow units. Where two or more hollow
units are used to make up the thickness of a wall, the
stretcher courses shall be bonded at vertical intervals not
exceeding 34 inches (864 mm) by lapping at least 3
inches (76 mm) over the unit below, or by lapping at vertical
intervals not exceeding 17 inches (432 mm) with
units that are at least 50 percent greater in thickness than
the units below.

Masonry bonded hollow walls. In masonry
bonded hollow walls, the facing and backing shall be
bonded so that not less than 4 percent of thewall surface of
each face is composed of masonry bonded units extending
not less than 3 inches (76 mm) into the backing. The distance
between adjacent bonders shall not exceed 24 inches
(610 mm) either vertically or horizontally.

Bonding with wall ties or joint reinforcement.

Bonding with wall ties. Except as required by
Section 2109.6.3.1.1, where the facing and backing (adjacent
wythes) of masonry walls are bonded with wire size
W2.8 (MW18) wall ties or metal wire of equivalent stiffness
embedded in the horizontal mortar joints, there shall
be at least one metal tie for each 41/2 square feet (0.42 m2)
of wall area. The maximum vertical distance between ties
shall not exceed 24 inches (610 mm), and the maximum
horizontal distance shall not exceed 36 inches (914 mm).
Rods or ties bent to rectangular shape shall be used with
hollow masonry units laid with the cells vertical. In other
walls, the ends of ties shall be bent to 90-degree (1.57 rad)
angles to provide hooks no less than 2 inches (51 mm)
long.Wall ties shall be without drips. Additional bonding
ties shall be provided at all openings, spaced not more than
36 inches (914 mm) apart around the perimeter andwithin
12 inches (305 mm) of the opening.

Bonding with adjustable wall ties.
Where the facing and backing (adjacent wythes) of
masonry are bonded with adjustable wall ties, there
shall be at least one tie for each 1.77 square feet (0.164
m2) of wall area. Neither the vertical nor horizontal
spacing of the adjustable wall ties shall exceed 16
inches (406 mm). The maximum vertical offset of bed
joints from one wythe to the other shall be 11/4 inches
(32 mm). The maximum clearance between connecting
parts of the ties shall be 1/16 inch (1.6 mm). When
pintle legs are used, ties shall have at least two wire
size W2.8 (MW18) legs.

Bonding with prefabricated joint reinforcement.
Where the facing and backing (adjacent
wythes) of masonry are bonded with prefabricated joint
reinforcement, there shall be at least one cross wire serving
as a tie for each 22/3 square feet (0.25m2) ofwall area.
The vertical spacing of the joint reinforcing shall not
exceed 24 inches (610 mm). Cross wires on prefabricated
joint reinforcement shall not be less than W1.7
(MW11) and shall be without drips. The longitudinal
wires shall be embedded in the mortar.

Bonding with natural or cast stone.

Ashlar masonry. In ashlar masonry, bonder
units, uniformly distributed, shall be provided to the
extent of not less than 10 percent of the wall area. Such
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bonder units shall extend not less than 4 inches (102 mm)
into the backing wall.

Rubble stone masonry. Rubble stone
masonry 24 inches (610 mm) or less in thickness shall
have bonder units with a maximum spacing of 36 inches
(914 mm) vertically and 36 inches (914 mm) horizontally,
and if the masonry is of greater thickness than 24
inches (610 mm), shall have one bonder unit for each 6
square feet (0.56 m2) of wall surface on both sides.

International Building Code 2109.6.1

General. The facing and backing of multiwythe
masonry walls shall be bonded in accordance with Section
2109.6.2, 2109.6.3 or 2109.6.4.

International Building Code 2109.6.2

Bonding with masonry headers.

International Building Code 2109.6.2.1

International Building Code 2109.6.2.2

International Building Code 2109.6.2.3

International Building Code 2109.6.3

Bonding with wall ties or joint reinforcement.

International Building Code 2109.6.3.1

International Building Code 2109.6.3.1.1

International Building Code 2109.6.3.2

International Building Code 2109.6.4

Bonding with natural or cast stone.

International Building Code 2109.6.4.1

International Building Code 2109.6.4.2

International Building Code 2109.6.5

Masonry bonding pattern.

Masonry laid in running bond. Each wythe
of masonry shall be laid in running bond, head joints in
successive courses shall be offset by not less than
one-fourth the unit length or the masonry walls shall be
reinforced longitudinally as required in Section
2109.6.5.2.

Masonry laid in stack bond. Where unit
masonry is laid with less head joint offset than in Section
2109.6.5.1, the minimum area of horizontal reinforcement
placed in mortar bed joints or in bond beams spaced
not more than 48 inches (1219 mm) apart, shall be
0.0003 times the vertical cross-sectional area of thewall.

International Building Code 2109.6.5.1

International Building Code 2109.6.5.2

International Building Code 2109.7

Anchorage.

General. Masonry elements shall be anchored in
accordance with Sections 2109.7.2 through 2109.7.4.

Intersecting walls. Masonry walls depending
upon one another for lateral support shall be anchored or
bonded at locations where they meet or intersect by one of
the methods indicated in Sections 2109.7.2.1 through
2109.7.2.5.

Bonding pattern. Fifty percent of the units at
the intersection shall be laid in an overlapping masonry
bonding pattern, with alternate units having a bearing of
not less than 3 inches (76 mm) on the unit below.

Steel connectors.Walls shall be anchored by
steel connectors having a minimum section of 1/4 inch
(6.4 mm) by 11/2 inches (38 mm), with ends bent up at
least 2 inches (51 mm) or with cross pins to form anchorage.
Such anchors shall be at least 24 inches (610 mm)
long and the maximum spacing shall be 48 inches (1219
mm).

Joint reinforcement. Walls shall be
anchored by joint reinforcement spaced at a maximum
distance of 8 inches (203 mm). Longitudinal wires of
such reinforcement shall be at least wire size W1.7 (MW
11) and shall extend at least 30 inches (762 mm) in each
direction at the intersection.

Interior nonload-bearing walls. Interior
nonload-bearing walls shall be anchored at their intersection,
at vertical intervals of not more than 16 inches
(406 mm) with joint reinforcement or 1/4-inch (6.4 mm)
mesh galvanized hardware cloth.

Ties, joint reinforcement or anchors. Other
metal ties, joint reinforcement or anchors, if used, shall
be spaced to provide equivalent area of anchorage to that
required by this section.

Floor and roof anchorage. Floor and roof diaphragms
providing lateral support to masonry shall comply
with the live loads in Section 1607.3 and shall be connected
to the masonry in accordance with Sections 2109.7.3.1
through 2109.7.3.3. Roof loading shall be determined in
accordance with Chapter 16 and, when net uplift occurs,
uplift shall be resisted entirely by an anchorage system
designed in accordance with the provisions of Sections 2.1
and 2.3, Sections 3.1 and 3.3 or Chapter 4 ofACI 530/ASCE
5/TMS 402.

Wood floor joists.Wood floor joists bearing
on masonry walls shall be anchored to the wall at intervals
not to exceed 72 inches (1829 mm) by metal strap
anchors. Joists parallel to thewall shall be anchored with
metal straps spaced not more than 72 inches (1829 mm)
o.c. extending over or under and secured to at least three
joists. Blocking shall be provided between joists at each
strap anchor.

Steel floor joists. Steel floor joists bearing on
masonry walls shall be anchored to the wall with 3/8-inch
(9.5 mm) round bars, or their equivalent, spaced not
more than 72 inches (1829 mm) o.c. Where joists are parallel
to thewall, anchors shall be located at joist bridging.

Roof diaphragms. Roof diaphragms shall be
anchored to masonry walls with 1/2-inch-diameter (12.7
mm) bolts, 72 inches (1829 mm) o.c. or their equivalent.
Bolts shall extend and be embedded at least 15 inches
(381 mm) into the masonry, or be hooked or welded to
not less than 0.20 square inch (129 mm2) of bond beam
reinforcement placed not less than 6 inches (152 mm)
from the top of the wall.

Walls adjoining structural framing. Where
walls are dependent upon the structural frame for lateral
support, they shall be anchored to the structural members
with metal anchors or otherwise keyed to the structural
members. Metal anchors shall consist of 1/2-inch (12.7 mm)
bolts spaced at 48 inches (1219 mm) o.c. embedded 4 inches
(102 mm) into the masonry, or their equivalent area.

International Building Code 2109.7.1

General. Masonry elements shall be anchored in
accordance with Sections 2109.7.2 through 2109.7.4.

International Building Code 2109.7.2

Ties, joint reinforcement or anchors. Other
metal ties, joint reinforcement or anchors, if used, shall
be spaced to provide equivalent area of anchorage to that
required by this section.

International Building Code 2109.7.2.1

International Building Code 2109.7.2.2

International Building Code 2109.7.2.3

International Building Code 2109.7.2.4

International Building Code 2109.7.2.5

Ties, joint reinforcement or anchors. Other
metal ties, joint reinforcement or anchors, if used, shall
be spaced to provide equivalent area of anchorage to that
required by this section.

International Building Code 2109.7.3

International Building Code 2109.7.3.1

International Building Code 2109.7.3.2

International Building Code 2109.7.3.3

International Building Code 2109.7.4

International Building Code 2109.8

Adobe construction. Adobe construction shall comply
with this section and shall be subject to the requirements of this
code for Type V construction.

Unstabilized adobe.

Compressive strength. Adobe units shall
have an average compressive strength of 300 psi (2068
kPa) when tested in accordance with ASTM C 67. Five
samples shall be tested and no individual unit is permitted
to have a compressive strength of less than 250 psi
(1724 kPa).

Modulus of rupture. Adobe units shall have
an average modulus of rupture of 50 psi (345 kPa) when
tested in accordance with the following procedure. Five
samples shall be tested and no individual unit shall have a
modulus of rupture of less than 35 psi (241 kPa).
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Support conditions. A cured unit shall
be simply supported by 2-inch-diameter (51 mm)
cylindrical supports located 2 inches (51 mm) in from
each end and extending the full width of the unit.

Loading conditions.A2-inch-diameter
(51 mm) cylinder shall be placed at midspan parallel
to the supports.

Testing procedure.Avertical load shall
be applied to the cylinder at the rate of 500 pounds per
minute (37 N/s) until failure occurs.

Modulus of rupture determination.
The modulus of rupture shall be determined by the
equation:
(Equation 21-4)

Moisture content requirements. Adobe
units shall have a moisture content not exceeding 4 percent
by weight.

Shrinkage cracks. Adobe units shall not
contain more than three shrinkage cracks and any single
shrinkage crack shall not exceed 3 inches (76 mm) in
length or 1/8 inch (3.2 mm) in width.

Stabilized adobe.

Material requirements. Stabilized adobe
shall comply with the material requirements of
unstabilized adobe in addition to Sections 2109.8.2.1.1
and 2109.8.2.1.2.

Soil requirements. Soil used for stabilized
adobe units shall be chemically compatible with
the stabilizing material.

Absorption requirements. A 4-inch
(102 mm) cube, cut from a stabilized adobe unit dried
to a constant weight in a ventilated oven at 212F to
239F (100C to 115C), shall not absorb more than
21/2 percent moisture by weight when placed upon a
constantly water-saturated, porous surface for seven
days. A minimum of five specimens shall be tested
and each specimen shall be cut from a separate unit.

Allowable stress. The allowable compressive
stress based on gross cross-sectional area of adobe shall not
exceed 30 psi (207 kPa).

Bolts. Bolt values shall not exceed those set
forth in Table 2109.8.3.1.

Construction.

General.

Height restrictions. Adobe construction
shall be limited to buildings not exceeding one
story, except that two-story construction is allowed
when designed by a registered design professional.

Mortar restrictions. Mortar for stabilized
adobe units shall comply with Chapter 21 or
adobe soil. Adobe soil used as mortar shall comply
with material requirements for stabilized adobe. Mortar
for unstabilized adobe shall be portland cement
mortar.

Mortar joints. Adobe units shall be laid
with full head and bed joints and in full running bond.

Parapet walls. Parapet walls constructed
of adobe units shall be waterproofed.

Wall thickness. The minimum thickness of
exterior walls in one-story buildings shall be 10 inches
(254 mm). The walls shall be laterally supported at intervals
not exceeding 24 feet (7315 mm). The minimum
thickness of interior load-bearing walls shall be 8 inches
(203 mm). In no case shall the unsupported height of any
wall constructed of adobe units exceed 10 times the
thickness of such wall.

Foundations.

Foundation support. Walls and partitions
constructed of adobe units shall be supported by
foundations or footings that extend not less than 6
inches (152 mm) above adjacent ground surfaces and
are constructed of solid masonry (excluding adobe) or
concrete. Footings and foundations shall comply with
Chapter 18.

Lower course requirements. Stabilized
adobe units shall be used in adobe walls for the
first 4 inches (102 mm) above the finished first-floor
elevation.

Isolated piers or columns. Adobe units shall
not be used for isolated piers or columns in a load-bearing
capacity. Walls less than 24 inches (610 mm) in
length shall be considered isolated piers or columns.
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Tie beams. Exterior walls and interior
load-bearing walls constructed of adobe units shall have
a continuous tie beam at the level of the floor or roof
bearing and meeting the following requirements.

Concrete tie beams. Concrete tie
beams shall be a minimum depth of 6 inches (152
mm) and a minimum width of 10 inches (254 mm).
Concrete tie beams shall be continuously reinforced
with a minimum of two No. 4 reinforcing bars. The
ultimate compressive strength of concrete shall be at
least 2,500 psi (17.2 MPa) at 28 days.

Wood tie beams. Wood tie beams shall
be solid or built up of lumber having a minimum nominal
thickness of 1 inch (25 mm), and shall have a minimum
depth of 6 inches (152 mm) and a minimum
width of 10 inches (254 mm). Joints in wood tie
beams shall be spliced a minimum of 6 inches (152
mm). No splices shall be allowed within 12 inches
(305 mm) of an opening.Wood used in tie beams shall
be approved naturally decay-resistant or pressure-
treated wood.

Exterior finish. Exterior walls constructed
of unstabilized adobe units shall have their exterior surface
covered with a minimum of two coats of portland
cement plaster having a minimum thickness of 3/4 inch
(19.1 mm) and conforming to ASTM C 926. Lathing
shall comply with ASTM C 1063. Fasteners shall be
spaced at 16 inches (406 mm) o.c. maximum. Exposed
wood surfaces shall be treated with an approved wood
preservative or other protective coating prior to lath
application.

Lintels. Lintels shall be considered structural
members and shall be designed in accordance with the
applicable provisions of Chapter 16.

International Building Code 2109.8.1

Unstabilized adobe.

Support conditions. A cured unit shall
be simply supported by 2-inch-diameter (51 mm)
cylindrical supports located 2 inches (51 mm) in from
each end and extending the full width of the unit.

Loading conditions.A2-inch-diameter
(51 mm) cylinder shall be placed at midspan parallel
to the supports.

Testing procedure.Avertical load shall
be applied to the cylinder at the rate of 500 pounds per
minute (37 N/s) until failure occurs.

Modulus of rupture determination.
The modulus of rupture shall be determined by the
equation:
(Equation 21-4)

Moisture content requirements. Adobe
units shall have a moisture content not exceeding 4 percent
by weight.

Shrinkage cracks. Adobe units shall not
contain more than three shrinkage cracks and any single
shrinkage crack shall not exceed 3 inches (76 mm) in
length or 1/8 inch (3.2 mm) in width.

International Building Code 2109.8.1.1

International Building Code 2109.8.1.2

Support conditions. A cured unit shall
be simply supported by 2-inch-diameter (51 mm)
cylindrical supports located 2 inches (51 mm) in from
each end and extending the full width of the unit.

Loading conditions.A2-inch-diameter
(51 mm) cylinder shall be placed at midspan parallel
to the supports.

Testing procedure.Avertical load shall
be applied to the cylinder at the rate of 500 pounds per
minute (37 N/s) until failure occurs.

Modulus of rupture determination.
The modulus of rupture shall be determined by the
equation:
(Equation 21-4)

International Building Code 2109.8.1.2.1

Support conditions. A cured unit shall
be simply supported by 2-inch-diameter (51 mm)
cylindrical supports located 2 inches (51 mm) in from
each end and extending the full width of the unit.

International Building Code 2109.8.1.2.2

Loading conditions.A2-inch-diameter
(51 mm) cylinder shall be placed at midspan parallel
to the supports.

International Building Code 2109.8.1.2.3

Testing procedure.Avertical load shall
be applied to the cylinder at the rate of 500 pounds per
minute (37 N/s) until failure occurs.

International Building Code 2109.8.1.2.4

Modulus of rupture determination.
The modulus of rupture shall be determined by the
equation:
(Equation 21-4)

International Building Code 2109.8.1.3

Moisture content requirements. Adobe
units shall have a moisture content not exceeding 4 percent
by weight.

International Building Code 2109.8.1.4

Shrinkage cracks. Adobe units shall not
contain more than three shrinkage cracks and any single
shrinkage crack shall not exceed 3 inches (76 mm) in
length or 1/8 inch (3.2 mm) in width.

International Building Code 2109.8.2

Stabilized adobe.

Material requirements. Stabilized adobe
shall comply with the material requirements of
unstabilized adobe in addition to Sections 2109.8.2.1.1
and 2109.8.2.1.2.

Soil requirements. Soil used for stabilized
adobe units shall be chemically compatible with
the stabilizing material.

International Building Code 2109.8.2.1

Material requirements. Stabilized adobe
shall comply with the material requirements of
unstabilized adobe in addition to Sections 2109.8.2.1.1
and 2109.8.2.1.2.

Soil requirements. Soil used for stabilized
adobe units shall be chemically compatible with
the stabilizing material.

International Building Code 2109.8.2.1.1

Soil requirements. Soil used for stabilized
adobe units shall be chemically compatible with
the stabilizing material.

International Building Code 2109.8.2.1.2

International Building Code 2109.8.3

Allowable stress. The allowable compressive
stress based on gross cross-sectional area of adobe shall not
exceed 30 psi (207 kPa).

Bolts. Bolt values shall not exceed those set
forth in Table 2109.8.3.1.

Construction.

General.

Height restrictions. Adobe construction
shall be limited to buildings not exceeding one
story, except that two-story construction is allowed
when designed by a registered design professional.

Mortar joints. Adobe units shall be laid
with full head and bed joints and in full running bond.

Parapet walls. Parapet walls constructed
of adobe units shall be waterproofed.

Foundations.

Lower course requirements. Stabilized
adobe units shall be used in adobe walls for the
first 4 inches (102 mm) above the finished first-floor
elevation.

Tie beams. Exterior walls and interior
load-bearing walls constructed of adobe units shall have
a continuous tie beam at the level of the floor or roof
bearing and meeting the following requirements.

Lintels. Lintels shall be considered structural
members and shall be designed in accordance with the
applicable provisions of Chapter 16.

International Building Code 2109.8.3.1

Bolts. Bolt values shall not exceed those set
forth in Table 2109.8.3.1.

International Building Code 2109.8.4

Construction.

General.

Height restrictions. Adobe construction
shall be limited to buildings not exceeding one
story, except that two-story construction is allowed
when designed by a registered design professional.

Mortar joints. Adobe units shall be laid
with full head and bed joints and in full running bond.

Parapet walls. Parapet walls constructed
of adobe units shall be waterproofed.

International Building Code 2109.8.4.1

General.

Height restrictions. Adobe construction
shall be limited to buildings not exceeding one
story, except that two-story construction is allowed
when designed by a registered design professional.

International Building Code 2109.8.4.1.1

Height restrictions. Adobe construction
shall be limited to buildings not exceeding one
story, except that two-story construction is allowed
when designed by a registered design professional.

International Building Code 2109.8.4.1.2

International Building Code 2109.8.4.1.3

Mortar joints. Adobe units shall be laid
with full head and bed joints and in full running bond.

International Building Code 2109.8.4.1.4

Parapet walls. Parapet walls constructed
of adobe units shall be waterproofed.

International Building Code 2109.8.4.2

International Building Code 2109.8.4.3

Foundations.

Lower course requirements. Stabilized
adobe units shall be used in adobe walls for the
first 4 inches (102 mm) above the finished first-floor
elevation.

International Building Code 2109.8.4.3.1

International Building Code 2109.8.4.3.2

Lower course requirements. Stabilized
adobe units shall be used in adobe walls for the
first 4 inches (102 mm) above the finished first-floor
elevation.

International Building Code 2109.8.4.4

International Building Code 2109.8.4.5

Tie beams. Exterior walls and interior
load-bearing walls constructed of adobe units shall have
a continuous tie beam at the level of the floor or roof
bearing and meeting the following requirements.

International Building Code 2109.8.4.5.1

International Building Code 2109.8.4.5.2

International Building Code 2109.8.4.6

International Building Code 2109.8.4.7

Lintels. Lintels shall be considered structural
members and shall be designed in accordance with the
applicable provisions of Chapter 16.