Where a partition runs parallel with the joists, and comes over a room below of considerable width, it may be prevented from sagging by trussing, as shown in Fig. 65. The extra cost of trussing is very small, and by it sagging can be entirely prevented ; and if the rods and braces are properly proportioned, the partition may be used to support floors or other partitions above. When built the partition should be slightly crowned, as the truss is sure to settle a little when the timbers have seasoned When trussing is employed care should be taken to see that the supports under the ends of the truss are ample.
Trussing, however, will not prevent settlement from shrinkage unless the bottom member of the truss is thoroughly seasoned.
The top of all wooden partitions gen-erally consists of a piece of studding called the cap, which is spiked to the upper end of the studding before the partition is raised. When the partition runs at right angles to the floor beams above the cap is fitted against the underside of the joists. When the partition is parallel with the floor beams above, and the latter are "strapped" underneath, the cap is nailed to the underside of the strapping, or furring, as shown in Fig. 60.
If the ceiling is not strapped, then the cap should be secured about every 3 feet by means of cross pieces, C, Fig. 66, spiked between the joists and to the top of the cap. Pieces of boards about 3 inches wider than the cap are then spiked on top of the latter to receive the ends of the laths.
In cheap work the cap A, Fig. 66, is sometimes omitted, and the board B is nailed directly to the studding, the latter being cut so that the underside of the board will be level with the bottom of the joists. The cross pieces, C, are then nailed above the board.
Where the span of the floor beams is more than 12 feet, the cap of all bearing partitions should be 3 inches thick, and if the span is over 16 feet and the studding 16 inches on centers, the cap should be 4 inches thick. In first-class work it is customary to specify Georgia pine or Oregon pine for the partition caps, as these woods are much stiffer than spruce or white pine, and not so apt to
During the construction of the building precaution should be taken to see that the end of a heavy timber, or the studs at the sides of a wide opening, are properly supported when they come over a space between the studs below.
The comers of all intersecting partitions should in all cases be made solid, either as at a, Fig. 67, or as at b. The arrangement shown at a is the best, but b answers very well if the stud c is nailed to the horizontal bridging between the other two. In no case should the laths be permitted to run by the end of a partition. Where the partition joins an outside wooden wall the corner should be made solid in the same way. When the partition comes near the middle of the wall, a 4x6 or 4x8 post should be set in the wall opposite the partition, as shown in Fig. 59.
Where wooden partitions join a brick wall it is a good plan to bolt the last stud to the wall once or twice in the height of the story by ¾-inch bolts embedded in the wall as it is built. Doing this strengthens the wall and tends to prevent cracks in the angle formed by the partition and wall.
Trussing Over Openings. - At the sides of all openings in partitions the studding should be doubled, and the partition over the opening trussed as shown either in Fig. 68 or Fig. 69.
When the opening does not exceed 3 feet, and there is no weight resting on the partition cap, the trussing may be omitted. The
"head" of the opening should always be formed of two pieces, kept 1 inch apart as shown in the figure, so that if the upper one sags it will not affect the lower one to which the door finish is nailed working of the doors; this sheathing should be put on when the partition is set up.
Bridging - All partitions should be bridged at least once in their height with 2-inch bridging the full width of the studding. The pieces should be placed horizontally, as shown in Fig. 58. Bridging stiffens the partition considerably and also prevents the passage of fire or vermin. When a partition is ceiled or wainscoted flush with the plaster it is necessary to cut in bridging between the studding to receive the nails. 70. Sliding Door Partitions. - These are made double, the studding being kept about 4 inches apart. When 2x3 studding can be obtained it is frequently used for these partitions, otherwise 2x4 studding must be used, cither placed flatways or edgeways. The former method is hardly stiff enough for stories exceeding 9½ feet in height, and should never be used for first-class work. If the partition is a bearing partition, one side may be made thicker than the other to carry the floor a ove. It is customary in the better class of buildings to sheath the inside of the partition with thin matched boarding to prevent the plaster from getting on the tracks or in any way interfering with the
Staggered Partitions, - It is desirable that partitions separating two tenements, stores or apartments, shall transmit sound as little as possible. The transmission of sound can be prevented considerably by filling the partition between the laths with mineral wool or with soft bricks laid up in mortar. The best way in which to accomplish this object, however, is to build the partition with two sets of studding, staggered as shown in Fig. 70, and kept entirely separate and independent of each other. If the two sides of the partition do not connect in any way, or touch each other, there will be very little sound transmitted through the partition. By tacking Cabot's deafening
"Quilt" to one set of studding the deadning will be nearly, if not absolutely, perfect, and the quilt will also, it is claimed, retard the progress of fire. Heavy felt paper may be used instead of the "Quilt" but the author believes that the "Quilt" is the better material for the purpose.*
*For a description of this "Quilt" see Chapter V (Building Stones).
Hot Air Pipes and Plumbing Pipes. - The position of all hot air and plumbing pipes should be carefully considered in making the plans, and provision for them made in framing the partition and floors. When a 4-inch soil pipe is carried in a partition the studding must be either 5 or 6 inches wide, or else the partition must be furred out around the pipes.