This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
It is very often necessary to construct a partition in some story of a building above the first and in such a position that there can be no support beneath it such as another partition. In this case the partition must be made self-supporting in some way. The usual method is to build what is known as a "trussed partition." This consists of a timber truss, light or heavy according as the distance to be spanned is small or large, which is built into the partition and covered over with lathing and plastering or with sheathing.
Fig. 215. One Form of Trussed Partition.
Figs. 215 and 216 show two forms of trussed partitions which are in common use. The one shown in Fig. 215 may be employed for a solid partition, or a partition with a door opening in the middle, while the one shown in Fig. 216 is applicable where the wall must be pierced by door openings in the sides. The truss must be so designed that it will occupy as little space as possible in a lateral direction, so that the partition need not be abnormally thick. If possible, it is best to make the truss so that it will go into a 4-inch partition, but if necessary 5- or 6-inch studding may be used and the truss members may be increased in size accordingly. The faces of the truss members should be flush with the faces of the partition studding so as to receive lathing or sheathing.
The size of the truss members depends entirely upon the weight which the partition is called upon to carry. Besides its own weight, a partition is often called upon to carry one end of a set of floor joists and sometimes it supports columns which receive the whole weight of a story above. In any case, the pieces must be very strongly framed or spiked together, and sound material free from shakes and knot holes must be used.
Fig. 216. Another Form of Trussed Partition.
In Fig. 217 is shown another form of trussed partition spanning the space between two masonry walls. As will be seen this partition is constructed in a slightly different way from the others illustrated and described above. At the two sides of the opening, which is in this case in the center of the partition, are two uprights which are made considerably heavier and stronger than the ordinary studding of which the frame of the partition is composed. In the figure, the opening is marked A, and the uprights at the sides of the opening are marked B B. In the upright pieces shoulders are formed, as shown at C in the figure, and into the shoulders are fitted braces which go diagonally across the partition to the lower corners near the wall where they are notched into the lowest member of the trussed frame. These diagonal pieces are marked D in the figure, and the lowest member of the frame is marked E. The piece E goes across from wall to wall and should run well into each wall as shown, so as to obtain a good bearing on the masonry and there should be a bearing plate or template of some kind under each end of it, as shown in the figure at the points F, to distribute the weight of the partition over a large surface of the masonry. For this purpose a thin iron plate will answer very well, or a large flat stone may be used. The piece E strengthens the floor construction and helps support the partition; the joists G rest on top of the piece E, or are notched over it, and the flooring H rests on these joists.
Fig. 217. Trussed Partition Spanning Space between Two Brick Walls.
Above the door opening A there are two diagonal pieces I which come together at the top of the partition, forming a small truss over the opening and completing the trussing of the partition. The diagonal pieces I meet the uprights on each side of the door opening at the point where the horizontal piece M meets the uprights, and they should be notched into either one or the other or both. The topmost member of the trussed partition frame is marked 0 in the figure, and on top of it rest the joists of the floor above, which either rest directly on it or are notched over it according to circumstances. These joists are marked P in the figure. They support the flooring R of the floor above the partition. The main members of the partition frame are filled in with ordinary studding, 2X4 inches or 2 X 3 inches, spaced 1 foot or 16 inches apart. These studs are marked S in the figure.