rubble

rubble. Rough, undressed stones of irregular shapes and sizes used in the construction of rubble-work walls with the mortar-joints fairly large, often requiring small pieces of stone (gallets) to be set into the mortar if the stones are especially irregular and difficult to fit reasonably closely together. Types of rubble-work include:random rubble: constructed of stones not of uniform size or shape laid in apparently random patterns, with no courses, needing great skill in its bonding so that continuous (and therefore weakening) vertical jointing can be eliminated, and requiring the wall to be sound by means of bonders (bond-stones), headers, or through-stones providing the transverse bond by extending through the thickness of the wall. Random rubble is also used without mortar (called dry-rubble or dry-stone walling) for field boundary-walls, the stability of which is entirely dependent on the careful interlocking and bonding of the stones;random rubble built to courses: similar to random uncoursed rubble in basic construction, except that the work is roughly levelled up to form courses the heights of which coincide with the quoins or jamb-stones of a reveal (often of dressed stones or brick dressing). Thus courses may be composed of one large irregular stone, then two or three stones set over each other, then two, then one, all laid to form a level upper surface;squared coursed rubble: rubble roughly formed of rectangular blocks, laid in courses, with the individual stones in a course all the same height, although the heights of courses themselves may vary, also called regular coursed rubble or ranged rubble;squared uncoursed rubble: roughly squared stones of different sizes placed in an uncoursed arrangement, with levellers (stones of low height), jumpers or risers as bond-or through-stones, and checks or snecks to fill in the areas left by the larger stones. It is also called square-snecked, snecked, or speckled rubble.In addition there are variations of walling which can be classed under rubble-work. They include:flint-walling: flints or cobbles in panels framed by lacing-courses of brick or stone to bond the wall together;knapped-flint walls: flints split to expose the hard dark interiors and dressed in pieces roughly square, which are then laid very closely together so that little, if any, mortar joints are visible. Panels of knapped flint are commonly found with dressed stone around them, especially in East Anglian churches of the Perp. Period (see flushwork), and the material always has to be used in conjunction with brick or stone for stability;Lake District masonry: slate from Cumberland and Westmorland in flat rough-faced or square-faced blocks dressed and laid in courses bedded in mortar set back from the faces on both sides of the wall, the centre of the wall being packed with dry stones without mortar. Blocks are closely fitted together, spalls being used to pack gaps, and laid tilted (watershot) towards the external wall to prevent water-penetration. Quoins are usually of dressed limestone;polygonal walling: usually found as a facing using stones such as ragstone set so that the joints form a net-like pattern all over the wall.

Bibliography

Gwilt (1903);
S. Hart (2000);
W. Papworth (1887);
Sturgis et al. (1901–2)