method of keeping the cavities clean is neither
practicable nor effective. The specified method for
concrete masonry unit and brick cavity wall is
effective, but may be deleted if the specifier is
reluctant to require it. Care must be taken (1) to
prevent damage to mortar joints, especially adjacent
to the washout holes, and (2) to prevent
accumulation of water at the bottom of the wall.
The cavities must be inspected to verify that they
are clean and functional.
For SOUTHNAVFACENGCOM projects, delete the second
sentence and substitute with the following: "Weep
holes shall be full open head joints 600 mm (20
inches o.c. for brick faced walls and minimum 50 mm
(2 inch) open head joints 900 mm (32 inches) o.c.
for concrete masonry unit construction."
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Wherever through-wall flashing occurs, provide weep holes to drain flashing
to exterior. Weep holes shall be [open head joints].[clear round holes not
less than 6 mm 1/4 inch in diameter] at 600 mm 24 inches o.c. Weep holes
shall be provided not more than 600 mm 24 inches on centers in mortar
joints of the exterior wythe above wall flashing, over foundations, bond
beams, and any other horizontal interruptions of the cavity. [Weep holes
shall be formed by placing short lengths of well-greased No. 10, 8 mm 5/16
inch nominal diameter, braided cotton sash cord in the mortar and
withdrawing the cords after the wall has been completed.] [Weep holes shall
be constructed using weep hole ventilators.] Other approved methods may be
used for providing weep holes. Weep holes shall be kept free of mortar and
other obstructions.
3.5
COMPOSITE WALLS
Masonry wythes shall be tied together with joint reinforcement or with unit
wall ties. Facing shall be anchored to concrete backing with wire dovetail
anchors set in slots built in the face of the concrete as specified in
Section [03300A CAST-IN-PLACE STRUCTURAL CONCRETE][03300N CAST-IN-PLACE
CONCRETE]. The facing wythe shall be anchored or tied to the backup at a
maximum spacing of 400 mm 16 inches on center vertically and 600 mm 24
inches on center horizontally. Unit ties shall be spaced not over 600 mm
24 inches on centers horizontally, in courses not over 400 mm 16 inches
apart vertically, staggered in alternate courses. Ties shall be laid not
closer than 16 mm 5/8 inch to either masonry face. Ties shall not extend
through control joints. Collar joints between masonry facing and masonry
backup shall be filled solidly with grout.
3.6
MORTAR
Mortar shall be mixed in a mechanically operated mortar mixer for at least
3 minutes, but not more than 5 minutes. Measurement of ingredients for
mortar shall be by volume. Ingredients not in containers, such as sand,
shall be accurately measured by the use of measuring boxes. Water shall be
mixed with the dry ingredients in sufficient amount to provide a workable
mixture which will adhere to the vertical surfaces of masonry units.
Mortar that has stiffened because of loss of water through evaporation
shall be retempered by adding water to restore the proper consistency and
workability. Mortar that has reached its initial set or that has not been
used within [2-1/2] [_____] hours after mixing shall be discarded.
SECTION 04200
Page 49
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