Partilions are defined as the interior walls of a house. Their number, the materials of which they are composed, and the mode of their construc tion frequently bear an important relation to the extent to which safeguards against fires are provided, and also to the degree of strength and thickness requisite in the party walls by which buildings in cities are separated. In the construction of fireproof buildings, it is considered essential that they should have no wood partitions unless they are protected by fireproof ma terial. It is said, however, that partitions built of two-inch tongued. and grooved planks placed together on end and plastered on both sides, either on wire or on dovetailed iron laths, have offered effective resistance to fire.
Brick ana' Timber Parlitions.—Partitions of large structures are gen erally formed of brickwork, while in smaller buildings or in the upper parts of dwellings wooden material is frequently used; but it is often filled in between the uprights by brickwork. In England, partitions of timber are called " quartering partitions," and they are generally framed. Thin par titions of wood are called " frame partitions." The method pursued in Paris is to frame and brace with strong seasoned timber. After the framed structure is complete, strong oak batten-laths from 2 to 3 inches wide are nailed up to the qnarterings horizontally, 4, 6, or 8 inches apart, in accordance with the character of the work, throughout the height of the partition; and the spaces between the quarterings and behind the laths are loosely built up with rough stone rubble, which is kept from falling out .by the laths until a strong mortar—composed mainly of plaster of Paris—laid on and pressed through from both sides at the same time, meets and incor porates so thoroughly that it fills up all the interstices and serves to strengthen the wooden material used, instead of deriving from it support.
The English Partition, formed of a similar combination of materials, depends for its strength chiefly upon the timber used, as the plastering work performed is nicely spread upon the surface of brick and wood; and these differences in effects represent important distinctions in methods of constructing- partitions consisting of wood, stone or brick, and plaster or mortar.
on the interior of buildings, on lath, brick, or stone, usually consists of three coats of mortar. The first—called the
" roug,h-" or " scratch-coat"—is generally formed of one part quicklime to four parts sand, with ox- or horse-hair mixed in to make the mass cohere. This coat, which is put on with the trowel, is about half an inch thick, and is pressed firmly in, so that it may enter well between and behind the laths. For rough walls, as in cellars, the scratch-coat may be sufficient. To furnish a better adhering surface for the second coat, the surface of the first coat, when it has dried slightly, is scratched or scarred with a pointed stick in lines crossing one another diagonally from 2 to 4 inches apart. The second coat is of the same hair-mortar—known as " coarse-stuff"— being from to of an inch in thickness, and is also in turn roughed before the application of the next coat, this roughing being frequently done with a hickory broom. The third and finer coat, intended as a finish, is p-,enerally but of an inch in thickness, and is frequently of stucco, which is made of one part lime to two parts fine sand. For a hard finish, one part plaster of Paris to two parts lime is used, without sand.
produce a fine finish upon inner walls, the surfare is hand-floated, or polished. This is done with a wooden trowel, called a " hand-float," and a water brush to dampen the wall as required. For very fine work the hand-float is made of cork. This careful smoothing upon each of the outer coats improves the strength and firmness of the wall, producing; an excellent and permanent covering. Sea-sand cannot be used in making plaster for this purpose, as it cannot be washed free from salt, which collects dainpness in the wall; the hair from salted hides should also be avoided, on account of its causing dampness in mortar.
make a perfect surface in fine walls and correct anv warping- or irregularities, the plasterer depends upon a process called " screeding." To accoinplish this, when the first rough, or scratch, coat of mortar is partially dry additional horizontal strips of the saine inortar, about 8 inches wide and from 2 tO 4 feet apart, are laid over the entire wall, so as to project from the first coat to the intended surface of the second coat. These are while soft carefully regulated by a plumb-line, and the second coat can then be readily brought to a perfectly flat surface cor responding to these strips or screeds.