rect location of SCUPPERS, when they are required in buildings equipped with sprinklers. Fig. 14 shows two types of COLUMN-RECESSES, used when the exterior faces of column and wall are in the same vertical plane. Fig. 15 shows a typical recess used when the faces of column and wall are offset. Fig. 14. Column Recesses and Bonds for Concrete Curtain Walls Fig. 15. Fig. 16. 3"Bonds 2'-0"Long. 1'-6"0. C.. to Walls. 1'-0"and Less in Width Typical Column-Recess for Offset Faces of Column and Wall 3. Brick Curtain Walls. The thickness of brick curtain walls is preferably 12 in, as it is difficult to make an 8-in brick wall weather-tight. When an 8-in brick wall is required, it is better to use METAL BONDS, as shown in Fig. 16, than to introduce full header-courses, as in the latter case it is difficult to make the wall tight; and in fact, if the effect of headers is required in an 8-in wall for architectural purposes, SNAP-HEADERS or half-bricks are recommended. The top of the spandrel beam supporting a brick curtain wall should be SLOPED 3/4 in in 12 in; and this slope may be easily gauged by placing a skewback on the beam-box, as illustrated in Figs. 17 and 19. As leaks are most likely to occur where the brickwork joins the concrete, it is particularly important to carefully GRADE THE CONCRETE forming the bed for Fig. 19. Method of Joining Brick Curtain Wall to Soffit of Concrete Lintel Beam Fig. 20. Brick Curtain Walls Flush with Face of Lintel Beam or Column the first course, and to actually build the brickwork into the column-recesses, as shown in Fig. 18. In order to make a tight joint directly under a spandrel beam, the thickness of the joints for the last five courses on the inside of the wall should be slightly reduced, as shown in Fig. 19, to leave room between the top course and the soffit of the beam for a joint at least 3/4 in thick. This space is filled with stiff wedge-mortar, tamped in as tightly as possible without displacing the exterior bricks. If, also, the exterior joint between brick and con crete is carefully pointed, the construction will be weather-tight. Fig. 20 shows sections of brick curtain walls flush with the concrete spandrel beams and columns. In these cases the splays are omitted from the corners of the concrete members. 4. Concrete Sills. Where brick curtain walls are used, the sills are ordinarily made of reinforced concrete, either precast or poured in place, and designed as shown in Fig. 21. The former method is preferable, especially for long sills, as it is difficult to obtain true lines when the sills are built in place. When this system is followed the sills are cast face-down and divided into units of any length convenient for handling, allowing %-in joints between sections. The total length should be computed to allow for a 4-in bearing at either end, or, where there are concrete columns, a recess of the same depth. Precast sills should be very carefully bedded upon a layer of stiff mortar, and the same precautions used as in the case of stone sills. When concrete sills are cast in place, a sheet of 2-ply tarred paper should be Fig. 24. Fig. 25 Twelve-Inch Curtain Wall of Terra-Cotta and Brick Veneer placed on top of the brickwork before the concrete is poured, so that the suction of the latter will not pull up the top corners of the bricks, Fig. 22. It is also necessary under these conditions to carefully protect the face of the brickwork below the sill with tarred paper or by other suitable means, in order to avoid CEMENT-STAINS, which are almost impossible to remove, especially from roughtexture brickwork. 5. Combination Curtain Walls. Concrete and brick can be used in combination as shown in Fig. 23, or hollow terra-cotta blocks and brick, as shown in Figs. 24 and 25. The latter form of construction, for a 12-in wall, is usually cheaper than a solid 12-in brick wall, and has the additional advantage of Fig. 26. Typical Sections of Parapet Walls. (For Flashing-Details, See page 316) making it dryer and less subject to water from condensation, because of the airspaces in the blocks. 6. Parapet Walls. The design of parapet walls follows the same principles described for curtain walls, and the diagrams in Fig. 26 illustrate several typical sections. On the whole, reinforced concrete is, structurally, the most suitable material. Stuccoed terra-cotta is not recommended, and when bricks are used they should be hard-burned or vitrified, and laid in cement mortar. If the roofsurfaces are graded by means of cinder or cinder-concrete fills, EXPANSIONJOINTS must be constructed as described on page 339, otherwise the expansion of these materials under the ordinary TEMPERATURE VARIATIONS obtaining in the vicinity of New York City may be sufficient to crack even strongly reinforced concrete parapets. All parapet walls should be bonded into the spandrel beams upon which they rest. For this purpose 2-in round rods, 3 ft long, and spaced 1 ft 6 in on centers, may be used for both concrete or brick construction. When parapet walls are cast between posts, the same sectional area and arrangement of reinforcement can be used as for low curtain walls. If, however, the parapet is continuous through several bays, there must be enough steel to distribute the effect of temperature variations; and when it forms, also, the spandrel beam of the roof-construction, enough to carry the incumbent load. When the loads are low the steel required to resist the bending moment may be too little to insure against temperature cracks and a minimum of about 0.30% to 0.40% based on the cross-sectional area of the wall should be taken. In CONTINUOUS CONSTRUCTION particular attention should be given to the reinforcement at the corners of a building, where the sectional area of the horizontal steel Fig. 27. Basement Wall Subjected to Earth-Pressure should be doubled by lapping the bars a few feet on each side of each corner. In designing solid parapets which entirely enclose a roof-area, additional provision should be made for rain-water in case the conductor pipes or drains become clogged. This is usually accomplished by leaving holes, about 4 by 8 in, in cross-section through the parapets, just above the finished roof-surface, or by inserting short lengths of 5-in pipe, or scuppers of other forms, in the parapet walls. 7. Cornices. Reinforced-concrete cornices are designed as CANTILEVER BEAMS, and may be poured monolithic with the spandrel beam of the roof-construction. The sectional area of steel required to resist the OVERTURNING MOMENT is placed near the upper surface of the concrete and a reinforcement of small rods is employed to distribute the stresses due to variations of temperature, and to tie the whole member together. For a small cornice faced with terracotta, the parapet wall itself may be reinforced as a vertical cantilever, and when |