Fig. 39.
Section Through Window.
Showing stone sill “weathered” at i, and “throated” at a. b—Wall. c—Inside plaster of room. d—Window-board. e—Oak sill. f—Beading and g—bottom rail of window-sash. h—Window. j—Iron tongue let into slot in i and e to prevent rain driving in.
If it is not proposed to coat exposed surfaces of brickwork, the wall may be formed of two parallel walls, two inches apart, and tied together by a sufficient number of bonding-ties of iron or glazed stoneware, or some other non-absorbent material. This arrangement is shown in Fig. 40.
An excellent plan is to fill in the narrow space between two such walls, as the building proceeds, with asphalte or slab slate, thus forming a vertical damp course, in the same way as below the ground level. The evils arising from damp can be avoided in every new house by proper methods of construction. In an old house, however, they are much more difficult to remove. The dampness is indicated on entering, by a peculiar mouldy smell, and by the discolouration and destruction of wall-papers, and dry rotting of floor timbers. In such a case a damp course may, with care and patience, be inserted in the wall, and the soil under the basement may be covered with concrete, and a dry-area excavated around the basement. Free ventilation under the floor-boards of the lower floors also helps in keeping the house dry.
Fig. 40.
Showing Hollow Wall and Bonding-ties of Glazed Stoneware.
a—Cavity. b—Tie. c—Floor-joist. d—Wall-plate. e—Concrete foundation of wall.
The thickness of the walls of a house requires to be sufficient to ensure stability, to keep out the damp, and to prevent a too rapid loss of heat from the walls. The relative merits of the different materials employed for these purposes have been already considered. A thin-walled house is hot in summer, and cold in winter. The upper stories of houses are often built with too thin walls, the result being chilly bedrooms. A single-brick wall (9 inches thick) will rarely keep out the weather effectually, and frequently a brick-and-a-half wall (14 inches thick) is insufficient for this purpose. The bricks should be so interlaced as to “bond” or tie the wall together in all directions. The strength of walls may be increased by the introduction of hoop-iron between the courses of brickwork.
In the construction of fire-places and chimneys, it is important to avoid the proximity of timber and wood-work to the inside of flues, as this is a common cause of fires.
Inside Coverings of Walls.
Plaster is made of lime mortar, or cement mortar; the former is generally preferred for domestic dwellings because it remains porous and moisture does not condense on it.