BOND-TINIRERS, are those horizontal pieces, built in stone or brick walls, for strengthening the building, and securing the battening, lath, and plaster : also the horizontal mould ings, or finishings of wood.
Bond-timbers disposed in tires, at altitudes corresponding to those of the horizontal mouldings, in the finishing of apart ments, as behind skirtings, bases. and surbases, are called common-band ; the scantling of which is generally four inches broad in the thickness of the wall, and two inches and a half thick in the altitude of the wall, so as to be equal in thick ness to a course of bricks. Bond-timbers placed in or near the middle of the story, of eight inches wide in the thickness of the wail, and five inches and a half deep (or about the length and thickness of two bricks) in the altitude of the wall, are called chain-timbers, or chain-bond. In brick buildings, when the lintels of a range of windows are considerably below the ceiling, the lintels may be con tinned through the walls as bond-timbers : in this case the thickness of the bond-timbers should be re!mlated by the necessary thickness of the lintels. When bond-timbers are also the wall-plates of floors or roofs, their scantling is generally the same as that of the chain-bond. The whole of the plate and chain-bond should be continued on one side of each internal wall, where the funnels or flues permit, as well as on the inside of the external walls, and properly notched and fastened at the angles. Bond timbers will, in most cases, prevent a building from cracking, where the foundation is infirm : they are easily executed in brickwork, or in coursed stone-work ; but in rubble-stone it is difficult, as the work must be leveled at every height in which they are disposed ; for N•hieh reason plugging is pre ferabh.• in such work. Plugging has one very material
advantage over bond-timbers, that in case of fire, the walls are less liable to tumble or warp, for they are not reduced in their thickness ; but this mutt be the ease where bond-timbers are employed, as they form a part of the thickness of the walls themselves. Bond-timbers should be. avoided in damp situa tions, such as basements of houses, as they are liable to rot and thus render the buildings insecure.
Within the last few years, a practice has arisen of intro ducing iron-hoop in place of bond-timber. Several strips or lengths of hoop are laid on at every four or five courses of bricks, and worked in as bond-timbers are—sometimes they are placed at intervals of three or four feet in the height of walls. It is pretended that great advantages, as regards danger from fire, result from this practice, but we are strongly inclined to the opinion that whatever good may arise fromthe incombustible nature of the material, is more than counterbalanced by the absence of the same strength as that given by timber-bond.
Bosns, are all the timbers disposed in the walls of a house, such as bond-timbers, lintels, and wall-plates. See FIR, in BOND.