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tition cap, which should also be done where heavy timbers bear between studs. The corners must be examined to see that they are made solid for lathing, Fig. 28, and that provision is made for running pipes, etc. If any of the unsupported partitions running parallel with the joists are found to have a considerable span so that there is danger of too much sagging, the difficulty may be overcome, at a small cost, by trussing the partition, and if such a partition is used in any way to support floors or other partitions overhead, this should always be done. The studs at the sides of all openings are to be doubled, and all openings of more than 3 feet are to be trussed. The head of every opening should be doubled, with the lower piece 1 inch from the upper, so that if there is any sagging of the upper or weight-bearing piece, that will not affect
Fig. 29. Typical Sheet-Metal
Joists and Beams
Fig. 30. Structural Steel Shapes with
Prongs to Hold Metal Lath
the lower one to which the finish is nailed. All the partitions should be bridged, and all sliding-door pockets sheathed with end joints secured, to avoid every possibility of a board starting off. The lining of sliding-door pockets should be set upon heavy sheathing paper in such a way as to prevent the very annoying air drafts from the cellar.
Sheet-Metal Joists and Beams. Of a later development are the various patterns of framing-members constructed of sheet metal in shapes to perform the offices of girders, joists, studding, rafters, and other parts of the skeleton of a house. The beams of different makes consist in the main of a web member and flanges, either formed of a single sheet or riveted together in the form of I-beams, T-bars, and other shapes common to rolled steel, Fig. 29. These, being made of sheet steel, are somewhat limited as to strength compared with rolled-steel shapes, but they are well adapted to houses, ordinary public buildings, and mercantile buildings where moderate loads are to be carried. In many of their shapes the sheet steel of the flange or web is pierced and forced out in the form of prongs, Fig. 30, to which metal lathing may be secured by bending down the prongs, thus making a metal structure which is light and can be quickly erected up to the point of plastering.
MASON WORK Chimneys. While these matters are being followed out by the carpenter, the mason must have started the chimneys, since
the roof cannot be finished until the chimneys are topped out. The bricks which are furnished should be carefully inspected, and any that are soft, or easily broken by striking together, should be ordered off the grounds at once. The specifications call for good hard bricks. If the contractor is
honest he will have ordered suitSTUDDING
able bricks, and if they are reANA
jected the loss will be the dealer's
and not his. Fig. 31. Typical Chimney Construction
Inside of Chimney. Next in importance to the quality of the brick is the smoothness of the inside of the flues; this is best secured in unlined flues by cleaning off with the trowel the mortar which squeezes out of each joint as the bricks are laid. In some localities it is customary to plaster the inside of the flues with mortar, but there is always danger that after a while this plastering may become loose and block the flues. Chimney bricks should be laid solid in mortar, so that no cracks are left for the passage of sparks. The best plan, and what is specified in this case, is to use linings of vitrified clay. These not only give a smooth flue, but add strength to the chimney and permit the use of 4-inch walls everywhere. All ash doors, clean-outs, and thimbles should be of ample size, and set as the work goes up, and the withes bonded into the outer walls every 6 or 8 courses, Fig. 31. This will not be done unless close watch is kept by the superintendent.
Outside of Chimney. The rough fireplaces must be formed, with wrought-iron bars over each opening, and the outside of the chimney must be thoroughly plastered from cellar to roof. The topping out of the chimney is to be done with the hardest of the bricks laid in Portland cement mortar. If there is planned an enlargement of the chimney where it shows above the roof, this must be done below the roof boards so that there may not be the overhanging projection of the bricks just above the roof often found in old chimneys, for the settlement of the chimney, which is likely to occur, will leave the top supported by the overhang upon the roof and open a dangerous seam at this point. The settlement of chimneys is a matter which it is necessary to consider at all times as it is almost certain that there will be an unequal movement between the chimney and the house. If the chimney stands upon a ledge or other immovable foundation, the roof will invariably settle a little because of the natural shrinkage of the wood construction; but more often the chimney, by reason of its isolated foundation and the general shrinkage of the mortar joints, will settle more than the roof.
Method of Attachment to Roof. This danger of settlement, as well as the danger from fire, precludes direct attachment to any portion of the wooden construction. The chimneys are generally built, therefore, entirely free and are secured to the frame by strapiron ties, which bend enough to adjust themselves to any settlement, either of the chimney or of the frame. In the case of outside chimneys, where protection from the weather becomes necessary, this natural movement between the chimney and the house must be recognized, and the chimney should be constructed with a projection of brick in line with the frame so that the boarding may run over and break the joint, A, Fig. 31. Where the top of a small chimney stands clear above the house for more than 10 or 12 feet, it should be stayed to the roof with iron rods. Two rods should be used, spread as far apart as possible at the point of junction with the roof, to give a measure of lateral support to the chimney. Lead for counter-flashing is to be furnished by the carpenter, for the mason to build into the joints of the chimney above the roof boarding, and care must be taken to see that the pieces are of good size and are carefully cemented into the brickwork at least 6 inches above the roof, and that they are ready to be turned down over the flashings which the carpenter will build in with the shingles. Behind the chimney, the flashings must be built in to a height that will allow proper room for building a saddle, to turn the water to either side.
Caps. When the stone caps for the tops of the chimneys arrive, they should be carefully measured on the ground, to be sure that they are of the correct size and that the holes for the flues are large enough, of the right shape, and in the proper position. For a large chimney with thick walls, it may be necessary to make the stone cap in pieces, and when this is done, the stones must be carefully tied together with galvanized iron or composition clamps. The excessive projection of bricks to form the chimney top is a thing to be avoided, i to inch to each course being all that should ever be allowed. In determining the projection of the top, it must always be remembered that the projection at the corners will appear greater than the natural projection of the courses, and there will be more danger of finding the completed top too large than too small. Projections from the shaft of the chimney must be protected on top by a weathering of Portland cement, and where an outside chimney is reduced in size the weatherings should be of stone.
Back Plaster. With the topping out of the chimneys, the mason, who in suburban work is very likely to be the plasterer as well, should turn his attention to the back plastering, if there is to be any. The back plastering is done in several ways, a common method being to nail strips to the sides of the studs and to lath upon these, the whole surface between the studs being covered with a rough coat of plaster, Fig. 32. Care must be taken to bring the mortar well out on the studs, and even then when the studs shrink there may be a continuous crack along the side of the stud from top to bottom. This, if it happens, will defeat the whole purpose of the back plastering and it is so likely to occur that other means than those just described are often taken to obtain a better result. One of the best methods is to lath the house on the studding and to put on a rough coat of plaster, then to fur off with 3-inch strips and lath and plaster again for the finished work, Fig. 32.
Fire Stops. In connection with the back plastering, may be done the fire-stopping of plaster or bricks. The principal point is to build with brick on the underpinning behind the sill up to the underside of floor, not only to prevent the spread of fire, but also
FURRING. E FINISHED PLASTERI Fig. 32. Two Methods of Finishing Off Back Plastering
to prevent rats from going from the cellar up into the walls and so all over the house. On the top of girders the same thing should be done, and if the girders support partitions, the brick work should be carried up between the studs for a distance of 3 courses or more above the floor, Fig. 33. By repeating this operation upon each partition cap and upon the girts of the outside frame, the whole house will be cut up into compartments and the circulation of fire and
vermin materially checked. In the case of a balloon frame where there are no girts, it is customary to run the floor boards out between the studs and to build up on these with the bricks. A further precaution, and a valuable one, is to lay a few courses of bricks upon