Bituminous saturated cotton fabric is stronger and is more extensible than bituminous saturated felt but is more expensive and more difficult to lay. At least one or two of the plies in a membrane should be of saturated cotton fabric to provide strength, ductility, and extensibility to the membrane. Where vibration, temperature changes, and other conditions conducive to displacement and volume changes in the basement are to be expected, the relative number of fabric plies may be increased. The minimum weight of bituminous saturated felt used in a membrane should be 13 lb per 100 ft2. The minimum weight of bituminous saturated woven cotton fabric should be 10 oz/yd2. Although a membrane is held rigidly in place, it is advisable to apply a suitable primer over the surfaces receiving the membrane and to aid in the application of the first mopped-on coat of hot asphalt or coal-tar pitch. Materials used in the hot-applied system should meet the requirements of the following current ASTM standards: Creosote primer for coal-tar pitchD43 Primer for asphaltD41 Coal-tar pitchD450, Type II AsphaltD449, Type A Cotton fabric, bituminous saturatedD173 Woven burlap fabric, bituminous saturatedD1327 Treated glass fabricD1668 Coal-tar saturated feltD227 Asphalt saturated organic feltD226 The number of plies of saturated felt or fabric should be increased with increase in the hydrostatic head to which the membrane is to be subjected. Five plies is the maximum commonly used in building construction, but 10 or more plies have been recommended for pressure heads of 35 ft or greater. The thickness of the membrane crossing the wall footings at the base of the wall should be no greater than necessary, to keep very small the possible settlement of the wall due to plastic flow in the membrane materials. The amount of primer to be used may be about 1 gal per 100 ft2. The amount of bitumen per mopping should be at least 41/2 gal per 100 ft2. The thickness of the first and last moppings is usually slightly greater than the thickness of the moppings between the plies. The surfaces to which the membrane is to be applied should be smooth, dry, and at a temperature above freezing. Air temperature should be not less than 50
F. The temperature of coal-tar pitch should not exceed 300
F and asphalt, 350
F. If the concrete and masonry surfaces are not sufficiently dry, they will not readily absorb the priming coat, and the first mopping of bitumen will be accompanied by bubbling and escape of steam. Should this occur, application of the membrane should be stopped and the bitumen already applied to damp surfaces should be

Construction must follow an industrialized-building sequence, rather than a conventional bar chart or CPM diagram. Unlike the procedure for conventional construction, the method of scheduling and monitoring for industrialized building requires that all trades closely follow the erection sequence and that every trade match the speed of erection. Thus, if the erection speed is eight apartments per day, every trade must automatically fall on the critical path. It is necessary that each of the subcontractors work at the rate of eight apartments per day, otherwise the scheduled date of occupancy will not be met. Metal Building Systems. These systems, produced by several manufacturers, coordinate design and construction of buildings whose primary component is a structural steel frame of standard, modular size; whose secondary members are massproduced, cold-formed steel shapes; whose roof is light-gage metal; and whose walls may be built of any material. Metal building systems generally cost less than other construction systems because of in-plant automation, use of precut and prepunched components, and quick erection on the site. Furthermore, costs are predictable. Metal buildings usually are purchased under design-build contracts. In addition, these systems offer flexibility, in that expansion can be readily achieved by removal of end walls, erection of new modular framing, and addition of matching walls and roof. (Metal Building Systems, Building Systems Institute, 1230 Keith Building, Cleveland, OH 44115-2180.) As outlined in this section, construction project management that will result in a profitable on-time job involves the organization and interplay of many talents. Engineers, accountants, field supervisors, construction labor. suppliers. and subcontractors, all aided by attorneys, insurance and bonding underwriters, the design professional, and the owner, must be organized and carefully coordinated. Those who succeed in this complex and difficult business are the ones who familiarize themselves thoroughly with the daily operations of their jobs. They are constantly learning by reading the latest literature and professional journals and by attending seminars and industry functions. They are alert and open-minded about new ideas. They understand the needs of the clients and the design professional and are able to tailor their services to them.

Brick and clay tile can be used as a plaster base if they are not smooth-surfaced or of a nonporous type. If the surface does not provide sufficient suction, it should offer a means for developing a mechanical bond, such as does scored tile. FIGURE 11.22 Application of a base coat of plaster to gypsum lath. (Gold Bond Building Products, a National Gypsum Division.) Plaster should not be applied directly to exterior masonry walls because dampness may damage the plaster. It is advisable to fur the plaster at least 1 in in from the masonry. Properly aged concrete block may serve in walls as a plaster base, but for block ceilings, a bonding agent or a special bonding plaster should be applied first. For precast or cast-in-place concrete with smooth dense surfaces, a bonding agent or a special bonding plaster should be used first. But if a plaster thickness of more than 3/8 in is required for concrete ceilings, or 5/8 in for concrete walls, metal lath should be secured to the concrete before plastering, in which case sanded plaster can be used. 11.25.8 Plaster Base Coats The base coat is the portion of the plaster finish that is applied to masonry or lath bases and supports the finish coat (Fig. 11.22). Except for veneer plasters, plaster applications may be three-coat (Fig. 11.21) or two-coat (Fig. 11.20). The former consists of (1) a scratch coat, which is applied directly to the plaster base, cross-raked after it has taken up, and allowed to set and partly dry; (2) a brown coat, which is surfaced out to the proper grounds, darbied (float-finished), and allowed to set and partly dry; and (3) the finish coat. Three-coat plaster is required over metal lath, 1/2-in gypsum lath spanning horizontal supports more than 16 in c to c, all gypsum lath attached by clips providing only edge support, and 3/8-in perforated gypsum lath on ceilings. The two-coat application is similar, except that cross-raking of the scratch coat is omitted and the brown coat is applied within a few minutes to the unset scratch coat. Three coats are generally preferred, because the base coat thus produced is stronger and harder. Veneer plaster applications, 1/16 in thick, may be one-coat or two-coat, both applied to special gypsum base (Arts. 11.25.1 and 11.25.5). The single coat is composed of a scratch coat without cross-raking and a double-up coat immediately applied, then worked to a smooth or textured finish. See also Art. 11.25.9 and Manual of Gypsum Lathing and Plastering, Gypsum