Bond Beam Block-Dimensions, Specifications, and Applications

Bond Beam Block-Dimensions, Specifications, and Applications
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Bond beam blocks are concrete masonry units which are manufactured with reduced webs (Fig. 1) or with knock-out webs (Fig. 2); the knock-out webs are removed prior to the placement of the unit in the bond beam.

The purpose of reduced webs or removable sections is to install horizontal bond beam reinforcement easily. In general, dimensions and specifications of the normal hollow block masonry is applicable for bond beam blocks. 

Bond Beam Block
Fig. 1: Bond Beam Block
Knock out Section Bond Beam Block
Fig. 2: Knock out Section Bond Beam Block

Dimension and Shape of Bond Beam

Bond beam block face dimensions of
203 mm by 406 mm, available in nominal thicknesses of 102, 152, 203, 254, 305,
356, and 406 mm. Specified dimensions of concrete masonry units are 9.5mm less
than nominal dimensions, so that 102 or 203mm module is maintained with 9.5 mm mortar
joints. ASTM C90 provides minimum face shell and web thicknesses for the
different sizes of concrete masonry units as in Table 1.

Table 1 Minimum thickness of Face shell
and webs

Nominal Width (W) of Blocks, mm Face Shell Thickness, minimum, mm Web Thickness, minimum, mm Equivalent
minimum, mm/linear m
76.2 and 102 19 19 136
152 25 25 188
203 32 25 188
254 35 29 209
305 and greater 38 29 209
Shape of Bond Beam Block
Fig. 3: Shape of Bond Beam Block


  • Bond
    beam block width, height, and length are allowed to vary by 3.2 mm from the
    specified dimensions.
  • Face
    shell and web thickness need to be in agreement with values provided in Table
  • Web
    thickness that is not in agreement with value of Table 1 can be accepted
    provided that equivalent structural capability has been established when tested.
  • Bond
    beam block shall be sound and free of cracks or other defects that interfere
    with the proper placement of the unit or significantly impair the strength or
    permanence of the construction.
  • Minor
    cracks, incidental to the usual method of manufacture or minor chipping
    resulting from customary methods of handling in shipment and delivery, are not
    grounds for rejection.


Bond beam
blocks are used in the construction of bond beams in the masonry wall of a
structure. Bond beams are courses of block constructed with specially
manufactured masonry units which are designed to receive horizontal
reinforcement and grout.

Moreover, bond
beams can be used in masonry bearing walls to serve as horizontal members along
the top of the walls, tying the walls together. They can be used below a line
of bar joists, so that joist anchors can be embedded into the grout of the bond

Furthermore, bond beams are used as lintels over doors and windows. They sometimes are located at the bottom of walls that span over an opening to make a deep beam. Bond beam reinforcement also can be used for crack control. In this application, there must be a break between bond beams at the control joints in a wall.

Finally, the area of steel required for bond beams used for crack control should be greater than that required for joint reinforcement. This is because the yield strength of the bars often is slightly less than that of the joint reinforcement and because the walls will undergo greater shrinkage due to the wetting effect of the grout during construction.

Bond Beam Block Installation and Reinforcement Placement
Fig. 4: Bond Beam Block Installation and Reinforcement Placement

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