This section is from the book "A Practical Treatise On The Joints Made And Used By Builders", by Wyvill J. Christy. Also available from Amazon: Practical treatise on the joints made and used by builders.
Angular Joint occurs in joggling, back rebating, etc.
Arch Joint is a bed joint between two voussoirs or arch stones. It usually radiates, and is always more inclined to the horizon near the key than at the springing, and hence is more compressed as it nears the latter position. The joints at the crown only begin to feel compression when the key is driven home, but are not actually compressed until the centre, which supports the whole weight of the crown near the key, is eased or struck. Unless the centre, therefore, is rigidly and properly braced, and the arch joints dressed perfectly straight and true, and made full and close, and the stones brought well home to their beds with a maul, the easing of the centre will cause the arch ring to alter its form and the joints to open at the soffit near the crown and at the back at some part of the haunches. Under these circumstances before striking the centre all open joints should be well wedged with pieces of slate and grouting. Plates of lead have been frequently introduced into arch joints to obtain an equal distribution of pressure and prevent the opening of the joints, but not always with the same success. Some allusion to the practice is made under Lead Joint. Stone and metal plugs or joggles are much used at the joints of ordinary arches, and to prevent sliding the beds used to be sometimes embossed and hollowed. All arch stones should, if possible, be either headers or stretchers, and the arch turned in one ring of equal-sized blocks, with the exception of the faces, which to preserve the bond require stones of two different lengths. Gothic arches often have a central joint which does not radiate. In a skew arch the joints usually form a spiral surface of uniform twist that radiates from the axis of the cylinder coinciding with the soffit of the arch.
Asphalte Joint occurs in masonry as a damp course, as described in the Bricklayers' Section. Iron cramps employed to bind together two blocks of stone put in hot and run with asphalte are secure against oxidation.
This results in worked granite when the surfaces of contact are first broached with the pick, and then finished for a certain depth with the axe or heavy hammer with sharp pointed edges required for bringing them to this sort of finish. Further particulars will be found under Fair Axed.
Generally the junction of the back of a stone with what it butts against, whether wood, iron, brickwork, or another stone. It is a joint that often needs tooling or dressing, and it may be found at the junction of stone steps, either with or without a rebate, or at the inner surfaces of chimney-piece jambs when jointed to return pieces, or at the meeting seam of a stone step with a boarded floor, etc. It always occurs behind the face of the work, excepting in an arch where it runs parallel or thereabouts to the soffit and forms the bed joint of the next ring or spandril. In ashlar facing the back joints are usually roughly drafted square with the beds.
Back Rebate Joint occurs in masonry when a back rebate or birdsmouth is formed, either to receive the sally of another stone, or to conceal a junction, as in the case of stone door and window architraves or dressings, which by such means are made to overlap and conceal the unsightly straight joint that would otherwise be conspicuous.