CONCRETE MASONRY WALL WEIGHTS

INTRODUCTION

Concrete masonry walls provide a range of benefits, including structural integrity, fire and sound resistance, energy efficiency, insect resistance, durability and architectural interest. Many of these attributes are measured quantitatively, and often vary directly with the weight of the concrete masonry wall.

Wall weights are used directly to calculate:

• Sound transmission class (STC) ratings, with heavier walls providing higher STC ratings and hence better sound insulation. See TEK 13-1B, Sound Transmission Class Ratings for Concrete Masonry Walls (ref. 1), for further information.
• Seismic base shear force, with heavier walls resulting in higher base shear values. See TEK 14-12B, Seismic Design Forces on Concrete Masonry Buildings (ref. 2), for further information.
• Heat capacity, an indication of thermal storage capacity, with heavier walls providing higher heat capacities and potentially better energy performance. See TEK 6-16A, Heat Capacity (HC) Values for Concrete Masonry Walls (ref. 3), for further information).
• Gravity loads (wall dead loads) on structural members such as lintels and foundations.
• Dead loads to resist uplift and overturning for high wind resistance.

Additional wall properties are also impacted by wall weight, although estimates of these properties are based on concrete density or aggregate type, rather than directly on wall weight. TEK 2-6, Density-Related Properties of Concrete Masonry Assemblies (ref. 4), also discusses the various physical and design properties influenced by the density of concrete masonry units. Examples of these properties include:

• Fire resistance ratings, with lower density walls providing more fire resistance in general. See TEK 7-1B, Fire Resistance Rating of Concrete Masonry Assemblies (ref. 5), for further information).
• Thermal resistance, with lower density walls providing higher R-values and potentially better energy performance. See TEK 6-1A, R-Values of Multi-Wythe Concrete Masonry Walls, and TEK 6-2A, R-Values for Single Wythe Concrete Masonry Walls (refs. 6, 7), for further information.

Tables 1 through 8 list concrete masonry wall weights for 4 to 16 inch (102 to 406 mm) thick single wythe walls. Wall weights for grouted 4-in. (102-mm) concrete masonry walls are not provided. Because of the small core size and resulting difficulty in consolidating grout, these units are rarely grouted.

Weights listed in the tables are based on the following assumptions.

• Minimum face shell & web thickness requirements of Standard Specification for Loadbearing Concrete Masonry Units, ASTM C 90-06 (ref. 8). These values apply to most currently available concrete masonry units. The 2006 edition of ASTM C 90 included slightly reduced minimum face shell thickness requirements for concrete masonry units 10 in. (254 mm) and greater in width. These smaller face shells result in slightly lower calculated wall weights for 10, 12-, 14- and 16-in. (254-, 305-, 356-, and 406-mm) units. Note that even though ASTM C 90-06 is not referenced in the International Building Code (ref. 9) until the 2009 edition, and in Building Code Requirements for Masonry Structures (ref. 10) until the 2008 edition, designers should be aware that many concrete masonry producers started complying with the reduced face shell requirements at a much earlier date. When using dead loads for beneficial effects such as overturning resistance, it is advised that the lower wall weights based on ASTM C 90-06 be used.
• Except as noted in Table 2, units have nominal face dimensions of 16 in. (406 mm) long by 8 in. (203 mm) high, as shown in Figure 1.
• All mortar joints are ⅜ in. (9.5 mm) thick. The mortar joint depth is equal to the thickness of the face shell or web on which it is placed (i.e., there is no excess mortar).
• Each unit has square ends and two square cores, as shown in Figure 1.
• Mortar density is 125 pcf (2,003 kg/m³).
• Grout density is 140 pcf (2,243 kg/m³).
• There is no excess grout in the wall.

NCMA and the companies disseminating this technical information disclaim any and all responsibility and liability for the accuracy and the application of the information contained in this publication.