Copyright Goodheart-Willcox Co., Inc. 276 Section 4 Construction Details Most energy codes and standards specify a maximum permissible value for the coefficient of thermal transmittance (U-value) for the building enve- lope as a function of wall weight. U-value is the heat flow through a building product based on the differ- ence between external and internal temperatures. The U-value is used in building energy calculations to deter- mine heat loss through the materials of the structure. Insulating materials used in construction are usually rated based on their ability to resist heat loss. This ability to resist heat loss, or R-value, is the thermal resistance of heat loss through a building product and is the reciprocal of the U-value, which is shown as R = 1/U. Solid Masonry Walls A solid masonry wall is a wall that is built of masonry units laid close together. All joints between the units are filled with mortar. Solid masonry units, hollow masonry units, or a combination of the two can be used. Solid masonry walls may be either loadbearing or nonloadbearing. The structural bond of these walls is provided by metal ties, masonry headers, or joint reinforcement. See Figure 14-1. Solid masonry walls can be classified by the types of units used in their construction. The following are examples of this classification: Solid units of brick or concrete brick and block. Hollow units of concrete block or structural clay tile. Composite (faced) walls composed of facing and backup units of different materials bonded in such a way that both facing and backup are loadbearing. Header blocks allow masonry headers to overlap block. Refer to the bottom center illustration in Figure 14-1. Goodheart-Willcox Publisher Figure 14-1. Typical solid masonry walls using brick, concrete block, and tile. Structural clay tile Facing Joint Reinforcement Masonry Bonded Joint reinforcement Structural clay tile Masonry headers Masonry header Masonry Headers Metal ties Header block Facing Masonry headers Composite (Faced) Metal Ties Masonry Bonded
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