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.
Although exterior plaster surfacing for dwellings has been in use in Europe for many years, it has but recently met with favor in this country. In Italy, plaster, or stucco, applied in large, unbroken expanses upon a stone or brick building, has long been a favorite method of construction. Frequently, too, this plaster surface is stained or colored and worked up into different designs. In England, France and Germany plaster has been more frequently used, in connection with a half-timbered frame, although these countries also contain instances of its use in large, unbroken, simple surfaces.
In modern American work, it is not often that a brick wall is covered with plaster, as the aesthetic possibilities in the use of rough hard-burnt brickwork have now long been recognized; and when this- the cheapest brick-building material - is employed upon a dwelling, it is itself utilized for the exterior surface and to obtain the exterior effect of the structure.
Plaster has been used in this country in imitation timbered houses for some years; but recently its employment in large, simple surfaces, unbroken by the cross-barring strips of dark wood, has become popular - a treatment much more appropriate to this country. We also possess some examples of brick and stone houses, two hundred years old or thereabouts, that were covered and surfaced with white plastering; but in the most recent of American plastered dwellings, this effect has been simulated by applying the plaster to a wooden frame lathed with a fine-meshed wire cloth.
In any plastered building, the cornices should be projected sufficiently far to protect the walls and all exposed upper surfaces of the plastering. The farther this projection, the more certain the safety of the plaster, especially in the northern sections of the country.
The essentials for successfully-wearing exterior plaster applied in modern fashion, are: A well-seasoned, shrunk, and settled frame; a solid, immovable foundation; and a carefully applied and thoroughly worked job of plastering. The framework should be somewhat better constructed and more carefully arranged to prevent movement or settlement than on an all-wooden building. Other than this, the dwelling to be plastered outside does not differ, in any part, from the ordinary house, until the structure has been framed and boarded in. For plastering, the boarding is then covered with a slightly better and more waterproof grade of paper than if shingling or clapboarding were intended. Outside of this papering, the house is furred with strips of furring, seven-eighths of an inch thick by one and one-eighth to one and one-quarter inches wide (for metal lathing they are to be placed nine inches apart, for wood laths twelve inches, on centers), and the lathing is applied upon these strips.
The best lath for exterior plastering is probably the No. 19 Clinton wire cloth. The wire is sufficiently large to be durable, and the mesh sufficiently open to allow the mortar to press through and completely fill and close in over the back of the wire, thus protecting from exposure to the elements or damage from water and rust, even if the plaster surface should leak sufficiently to admit water behind this covering.
Expanded metal is also used for this purpose, but is not generally considered so good a material, from the fact that it is impossible to cover entirely and protect the back of this lath with plastering, and therefore there is no means of certainly protecting it from the possibility of rusting.
Occasionally, on a small, low house of not over a story and a-half of wall height, the boarding may be omitted altogether The metal lath is then placed directly upon the furred studs, and plastered both outside and in to insure its absolute protection from damage by water. However, the shrinking of the studs opens a small crevice along each side -which has already been mentioned as occurring in back plastering -and it is thus possible that water may enter from the back and do considerable damage, even through the narrow space that this shrinkage provides. The omission of the outer boarding also somewhat injures the stiffness of the house, as a frame constructed in this way is not well braced as when the boarding is applied. Neither are the dwellers in the house so completely protected from the exterior weather, as the second air-space obtained between the papering and the exterior plastering is lost. This extra air-space is of assistance in keeping the house more equably warm in winter and cool in summer.
In the use of metal lath, it is always to be remembered that the absolute essential is to protect the lath from the action of water and rust. This once done - in whatever fashion - a permanent and lasting plaster surface is ensured. Sometimes the metal lath is wired and fastened to perpendicular iron furrings of tee-irons or angles, held to the wood frame with staples or some similar fastening, allowing any possible movement of the frame to occur without affecting or straining the plastic surface, which is, by this means disassociated from, while directly supported by, the house frame. Cracks around the windows and the angles of the buildings are thus prevented, but it is a more expensive form of construction, and is not now employed except in the larger and more expensive residences.
From the use of wire lath, there are occasionally obtained small surface cracks, especially if the lath joint happens to come at a place where some strain is afterward placed upon it, and particularly where it is weakened from the movement of adjacent portions of the building. For instance, if a perpendicular lath lap is made on the line of the edge of the window finish, a crack on the line of this joint is almost certain to appear in the plaster, extending both above and below the wood-surrounded opening. Care should be taken to cut the strips of lathing so that the joint will come at least nine or ten inches on either side of the edge of the window or door finish. All furrings should also be kept away and back from all angles, internal or external, upon the walls, so that a certain clinch may be effected by the plastering at these important points.