PART 1-GENERAL

Submittal

Submit full size color sample(s) of each color specified or selected from manufacturer's color palette. Submit product literature, test reports, and product certifications.

Quality Assurance

Decorative (veneer) concrete masonry units shall be Optimum Series™ Oversize Masonry Units as manufactured by County Materials Corporation, Eau Claire, WI (800-729-7701) and/or Premier Block Corporation, Eau Claire, WI (888-395-5584). All units shall conform to ASTM C 90 Loadbearing Concrete Masonry Units. Units shall be [specify style option] (Splitface, Ultra® Burnished, Essence™ Fine Finish Split, Elite® Series or Sculpted) units as designated on the drawings or in the specifications.

Construct a separate (not part of the actual building) sample wall panel not less than 4' by 4' with units in the pattern, color and shape as indicated in drawings and specifications.

Cleaning agents and methods shall be performed prior to approval of the sample panel. Walls erected without a sample panel will be considered approved "as is".

Delivery, Storage and Handling

Optimum Series™ Oversize Masonry Units shall be delivered to the job site on pallets and stacked only one pallet high on level ground. Delivered pallets shall be protected from inclement weather with a waterproof covering. Units shall be handled carefully to avoid breakage and damage.

Design Practices and Installation

Careful consideration should be given to the placement of control joints and the use of horizontal joint reinforcement, brick wall ties, weep holes and water-resistant sealants. It is expected that Optimum Series™ Oversize Masonry Units will be laid using the best concrete masonry construction practices. For maximum construction efficiency and economy, concrete masonry walls should be designed and constructed with modular coordination in mind. Standard dimensions for Optimum Series™ Oversize Masonry Units are equal to the nominal dimensions, less the thickness of one mortar joint (3/8"). Optimum Series™ Oversize Masonry Units should not be wetted prior to placement.

Control Joints

Control joints are one method used to relieve horizontal tensile stresses due to shrinkage of concrete masonry units, mortar, and when used, grout. They are essentially vertical separations built into the wall at locations where stress concentrations may occur. These joints reduce restraint and permit longitudinal movement. Concrete masonry requires vertical control joints to accommodate panel contraction.

Control Joint Placement

Control joints should be located where volume changes in the masonry due to drying shrinkage, carbonation, or temperature changes are likely to create tension in the masonry that will exceed it's capacity. The following are suggested methods to provide guidance in locating control joints. (see Figure 1)

1. At changes in wall height,

2. At changes in wall thickness, such as at pipe and duct chases and pilasters,

3. At (above) movement joints in foundations and floors,

4. At (below) movement joints in roofs and floors that bear on the wall,

5. Near one or both sides of door and window openings, (generally, a control joint is placed at one side of an opening less than 6 ft wide and at both jambs of openings over 6 ft wide). Control joints can be away from the opening if adequate tensile reinforcement is placed above, below and beside wall openings. Adjacent to corners of walls or intersections within a distance equal to half the control joint spacing requirement for that wall.

For more detailed control joint spacing, see NCMA Tek Note 10-2B.

Empirical Crack Control

For walls without openings or other points of stress concentration, control joints are used to effectively divide a wall into a series of isolated panels. Table 1 lists recommended maximum spacing of these control joints based on empirical criteria. For walls containing masonry parapets, consider the parapet as part of the masonry wall below if it is connected by masonry materials such as a bond beam unit when determining the length to height ratio.

Table 1

The control joint spacings of Table 1 have been developed based on the use of horizontal reinforcement to keep unplanned cracks closed as indicated in footnote.

Horizontal Joint Reinforcement

Continuous, 4" joint reinforcement is required for every course in all veneer applications and in the exterior wythe of composite wall construction. Nonstructural, horizontal, joint reinforcement, should not be continuous through a control joint, since this will restrict the horizontal movement. However, structural reinforcement, such as bond beam reinforcement at floor and roof diaphragms that resists diaphragm cord tension, must be continuous through the control joint, but provisions should be allowed for longitudinal movement.

Weep Holes

To properly drain water collected on any flashing or horizontal surface, weep holes must be provided immediately above the flashing or horizontal surface at all locations, following standard industry practices. Weep holes should be at least 1/4 inch in diameter, and should be spaced no further apart than 32 inch. o.c. horizontally. When using wick type material in the weep hole, the spacing should be reduced to a maximum of 16 inch o.c. (Figure 2)

Veneer Anchors

County Materials Corporation and Premier Block Corporation recommend using an anchor that allows for vertical and horizontal movement. Examples are DW-10 manufactured by Hohman Barnard or Type III veneer anchor w/triangular tie manufactured by Wire Bond. (Figure 3)

Flashing

The primary role of flashing is to intercept the flow of moisture through masonry and direct it to the exterior of the structure. Flashing is recommended for all locations where moisture may potentially penetrate into a wall and where the free drainage of water is blocked. Some of these critical locations include the top of walls and parapets, at all horizontal obstructions such as over openings, beneath sills, above shelf angles, and at the base of walls. Flashing may also be utilized in walls at ground level to serve as a moisture retarder to reduce the amount of water wicked up into the masonry above grade. Weep holes and vents also reduce the moisture content of masonry walls.

Project/Site Conditions

During construction of exposed concrete masonry, minimize mortar and grout smears on the face of the units. Mortar droppings that adhere to the exposed face of the units can be removed with a trowel or chisel after being allowed to harden. Any remaining mortar can then be removed with a stiff fiber brush. The base of the wall should be protected from mud splashing and mortar droppings by spreading plastic sheets four feet on the ground and three feet up the wall. Covering the tops of unfinished walls at the end of the workday prevents rain and outside elements from entering the wall and thus reduces the chance of efflorescence forming on the wall. Covers should be draped at least two feet down each side of the wall and a method provided to hold them in place.

Mortar and Mortar Joints

Use regular gray or a complementary color to match the Optimum Series™ Oversize Masonry Units. Concave or V-shaped tooling of joints, when the mortar is thumbprint hard, improves moisture resistance by compacting the mortar against the masonry unit to seal the joint. Raked, flush, struck, beaded, or extruded joints are not recommended as they do not compact the mortar and/or create ledges that intercept water running down the face of the wall. Head and bed joints should be the full thickness of the face shells for optimum water tightness.

Cleaning

Optimum Series™ Oversize Masonry Units can be cleaned using traditional masonry cleaning methods, such as mild masonry detergents/cleaners and power-washing systems properly applied. Strong acids, acid washes or chemicals with a strong acid reaction should not be used, since they may reduce the water repelling properties of treated masonry and etch the surface, distorting the color. Keep the masonry wall clean as the construction progresses and use a brush and water after the mortar has hardened.

Water Repellents

Optimum Series™ Oversize Masonry Units are manufactured with integral water repellents. This is to provide resistance to wind-driven rain, reduce the potential for efflorescence and staining from environmental pollutants, and enhance the color and texture of a wall. The same water repellent admixture should be used in the mortar, as was used in the block, to ensure compatibility and bond.

Extreme Weather Construction

Temperatures between 40 and 90°F (4.4 and 32.2°C) are considered "normal" temperatures for masonry construction and therefore do not require special procedures or protection protocols. When ambient temperatures fall below 40° F (4.4°C), the Specification for Masonry Structures requires consideration of special construction procedures. Similarly when the minimum daily temperature for grouted masonry or the mean temperature for ungrouted masonry falls below 40°F (4.4°C) during the first 48 or 24 hours after construction respectively, special protection considerations are required.

Rain and Masonry Construction

The presence of rain, or the likelihood of rain, should receive special consideration during masonry construction. Unless protected, masonry construction should not continue during heavy rains, as partially set or plastic mortar is susceptible to washout, which could result in reduced strength or staining of the wall. However, after approximately 8 to 24 hours of curing (depending upon environmental conditions), mortar washout is no longer of concern. When rain is likely, all construction materials should be covered. Newly constructed masonry should be protected from rain by draping a weather-resistant covering over the assemblage. The cover should be secured in place and extend over all mortar that is susceptible to washout.

(References: National Concrete Masonry Association TEKs)

County Materials Corporation Corporate Office
205 North Street,
P.O. Box 100
Marathon, WI 54448
800-289-2569

Premier Block Corporation
Corporate Office
1111 Menomonie Street
P.O. Box 910
Eau Claire, WI 54702
888-395-5584