4. Wall coverings may be classed as plain and ornamental. Plain wall coverings are used chiefly on buildings intended for manufacturing purposes and for such structures as are erected for temporary use; while ornamental coverings are generally used on the fronts of cheap city buildings, such as warehouses, stores, theater fronts, etc.

5. The sheet metal employed for this purpose is usually galvanized sheet iron or steel, the sheets being either plain, crimped, or corrugated.

Plain sheet iron is seldom used except for the most ordinary work, where appearance is not at all considered. The sheets are simply nailed to a backing of matched lining or ordinary sheathing, the object usually being to prevent the building from readily becoming ignited, should an adjacent building be on fire.

The chief objection to plain sheet siding, is the fact that the metal will bulge and become distorted in many different ways, until the whole side of the building will actually appear to be covered with large blisters.

6. Crimped sheet iron is superior to plain sheet iron for covering large flat surfaces, because the crimping helps to prevent the sheets from bulging, and thus, to a certain extent, avoids the blistered appearance so pronounced on plain sheet-iron siding. A clipping of crimped sheet metal is shown in Fig. 1. The sheet is crimped by passing it through ribbed or roughened rollers, which give it the appearance of being slightly corrugated. Crimped metal, however, differs from corrugated metal in that sheets of the former, after treatment, are practically as long as they were before the process, while in corrugating the sheet is shortened. The crimps are usually made across the sheet. while corrugations are run lengthwise.

Crimped sheets may be nailed to furring strips, or to studs or posts set at from 12 to 16 inch centers, providing the grooves run at right angles to the strips or studs. Thus, if furring strips are nailed on the studding, the grooves would be vertical, but if the sheets are nailed directly on the studding, the grooves would be horizontal. It is best, however, in every case to provide a solid flat backing for crimped sheet-metal work.

7. Corrugated sheet iron is preferable for siding where there is an extensive, unbroken surface. The corrugations not only strengthen the sheets, and thus enable them to be attached to furring strips as far apart as 4 feet, but they also relieve, by the play of light and shade, the monotony incident to a flat surface.

Corrugated sheet iron should always be fastened with the corrugations vertical, not so much for appearance as to obtain a perfectly water-tight siding with ordinary lap joints. Fig. 2 shows the method of forming vertical joints. The corrugations are simply lapped and the two sheets are nailed to the posts or studs a, a with flat-head galvanized-iron nails. The top edge of each sheet is nailed to cross-pieces b, b which are spiked or framed in between the posts. The horizontal joints of the sheets are lapped as shown in Fig. 3; cleats are riveted on as shown at a to bind the lower end of the sheet so as to make a close joint and also allow for expansion and contraction of the sheets. The top sheet should lap at least 2 inches over the nails.

Wall Coverings 378

Fig. 1.

Wall Coverings 379

Fig. 2.

Corrugated-iron sheets are often secured against sheathed walls, and the common practice is to nail them all around the edges, but, in this case, expansion and contraction soon loosen the sheets either by drawing the nails or by tearing the nail holes. The plan of attachment described above and illustrated in Fig. 3 is to be recommended even when the sheets are secured against a flat surface.

8. Fig. 4 shows how the corrugated sheets may be put on at the base of the framework. A base strip a,made in the form of an offset, is securely nailed to the wooden sill b, the strip being flanged so that it may cover the exposed portion of the wall. The sheets are clamped to the top edge of this strip with cleats 1 inch wide by 1/8 inch thick, similar to that shown in Fig. 3.

Wall Coverings 380

Fig. 3.

Wall Coverings 381

Fig. 4.

9. Fig. 5 shows the finish of the sheets at the eaves. The top edges are nailed to the plate a. A strip of wood b about 1 1/4 inches thick, cut on one edge to fit the profile of the corrugations of the roof, should be nailed to the upper edge of the plate. Another strip c of the same material is nailed to the lower edge of the plate. A facia of crimped sheet iron d covers both strips and forms a drip at its lower edge, as shown. This arrangement makes a neat, water-tight, and wind-proof connection between the siding and the roof.

Wall Coverings 382

Fig. 5.

10. Fig. 6 shows the finish at the corners of the building; this makes a water-tight junction and presents a neat appearance. Since the corrugated iron is laid against the framework, it is necessary to nail 7/8-inch wooden strips on the outer faces of the corner post a. The corrugated iron butts against the edges of these strips, and a crimped sheet-iron corner piece, is sprung over and locked into the corrugated wall sheet as shown.

Wall Coverings 383

Fig. 6.

This arrangement can also be used around any window or door opening. The arrangement shown in Fig. 4 may also be used over the lintels of any door or window opening.

11. Corrugations in common use measure about 2 1/2 inches, from center to center, and are about 3/4 inch deep.

Black corrugated iron should always be painted with metallic paint of the best quality before it is secured in place.

12. Stamped siding is most commonly employed for covering large flat surfaces of outer walls, the sheets being pressed to such a shape that they resemble rock-faced, or tooled, stonework or brickwork. This siding is stamped in plates 10 feet long by 2 feet wide, and the plates are sold by the lineal foot. Like crimped sheet metal, it is nailed to furring strips, to ordinary sheathing, or to brick walls, the vertical joints being lapped and closely nailed.

Particular care should be taken to lap all the vertical joints in sheet-metal work so that the heaviest rain storms will blow with the laps and not against them. It is noticeable in nearly every district that the strongest winds and greatest rain storms nearly always blow from certain directions; these directions should be determined, and the sheet-metal work should be arranged to prevent the rain from blowing into the seams.

Brick walls should always be thoroughly furred to receive the sheet-metal work. It is a mistake to suppose that sheet-metal work can be securely nailed into the joints, because expansion and contraction will very soon loosen the fastenings.