Walls: Constructive systems, problems, causes and solutions

“Walls, piers and columns all form part of the same system of enclosure of space and support of the roof. Stone and brick masonry are considered together as they are so similar, but mud brick has special problems of its own, so it is studied in a separate chapter. Timber walls must not be forgotten, but here the problems are not so much structural as the decay of the material itself… Each geographical region and period in history has had its own characteristic way of building walls. Therefore, each type of wall has different preservation and repair problems dependent upon its construction and strength of the primary and secondary materials; for example, unbaked brick laid in mud mortar, unboned stone blocks, closely fitted polygonal masonry laid dry and random rubble in lime mortar will age differently from say, bonded masonry laid in mortar or Roman mass concrete walls. Ruins can often be informative about the nature of structural systems, as the collapse pattern of a wall may show how it ultimately failed and thus how a similar type of wall should be reconstituted and strengthened.” From FEILDEN B.M., Conservation of Historic Buildings, Butterworths, London 1982, p. 61.