Sharing, as applied to excavations, has been dealt with previously; and it is now proposed to give the student an idea of shoring to buildings which require additional support, when the adjoining or part of their own property has been pulled down.
Elevation Fig. 916.
Section: Fig. 917.
In cases where large openings are to be cut into main walls it is necessary that the part above must be shored while the girders to carry it are being put in. This is done by means of struts, posts, or legs, raised perpendicularly from the balk-sills on the solid ground or floor made solid, and supporting needles going through holes cut above the height of the opening reauired, as Figs. 916 and 917, the whole being tightened up by wedges, at the feet of the posts, as shown on the side elevation-The dotted lines show the proposed position of the girders and the opening to be cut in the wall after the weight above has been secured by the shoring, which is generally constructed of balk-timber 10 or 12 inches square, as required.
When one house between two others has been pulled down (which is the more usual occurrence) a temporary timber framing, consisting of several trusses, is built between the two from wall to wall, to allow each to prop the other, as it were. These forms of course vary infinitely, and are of varying strengths, according to the spans and distances apart, if the depth of the opening requires more than one set of framing. A long plank is placed vertically up the walls of each house, and the framing is built in and wedged tight between them, as Fig. 919; or where one house is taller than the other, and the width requires a truss similar to king or queen posts in roofs, they are treated as in Fig. 920, though the work can be done in various other manners, and different men have different ideas on the subject.
Angles of buildings which require to be strutted, and end houses which cannot be strutted from another building, are dealt with by means of flying shares, as Fig. 921, with long timbers, or as in Fig. 922, with short timbers secured by boards nailed on each side, and bound together with hoop iron. The butting pieces in the ground, backed up by the vertical post solidly driven into the ground, should incline at right angles to the pressure of the chief shore or strut Each of the shores is secured at the top, as in Fig. 923, a hole being cut into the upright plank and wall, into which the pin or needle is driven. This pin is assisted by a cleat nailed above it, and the shore is butted up and wedged against it, as shown.
Scaffolding, as familiar to everybody, is a series of temporary platforms, raised up, as the building increases in height, to allow the men to work from them at various stages, and store their materials for immediate use. They consist of poles, ledgers, putlogs, boards, cords and wedges, the poles being the upright circular members, secured in the ground about 9 feet apart, as A, on Figs. 923 and 924. The ledgers, B, running longitudinally at every different rise of 4 or 5 feet, are secured by the cords 18 feet long, bound tightly round the two and wedged up. From the ledgers to and into holes in the wall (which is about 5 feet away) the putlogs C are laid every few feet to receive the boards D, which form the platform. When the framing is of any height it is braced, as shown by the ordinary scaffold poles, secured by the cords, and wedged like the ledgers.
Masonry requires stronger scaffolding, which is, therefore, usually strengthened for the purpose by the use of 3-inch battens, instead of 1 1/2 inch planks, to form the platform; and also it will not allow of putlogs going into the walls, in which case they are strutted up from one platform, or height, or putlog, to the other, by planks placed against the wall.
Elevation Fig. 923.
In Scotland the work is built from the inside, the working platforms being raised from floor to floor as the work proceeds.
Gabers scaffolds are little used, so it is unnecessary to enter into particulars about them, more than to say that the standards, putlogs, etc., are made by bolting deals together, the whole being cross-braced, and bolted to the standards and to one another, presenting an appearance like a quarry floor laid diagonally.