In broad terms there are three alternatives for repairing defective masonry; complete renewal, insitu surface restoration, or in some cases, consolidation.
The cause of masonry failure lies with factors such as incorrect detailing in original construction, incompatible materials placed beside one another, inadequate weatherings and regrettably the problem is often caused by bad repairs, in particular, the use of hard mortars for re-pointing or stucco repair. Lack of maintenance also leads ultimately to further damage of the building fabric.
Much the same principles apply to brickwork restoration as to stone. The spalling face can be cut back and restored forward with specialist repair mortars coloured and textured as required. Faces can be cut back and refaced or whole bricks totally cut out and new ones indented to match the surrounding substrate. Cracks can be repaired by grout or resin injection.
Terracotta and Faience
The failure of terracotta and faience facades is frequently due to the iron or steel reinforcement behind the surface which has inadequate protection from the weak mix clinker concrete surrounding it. Water penetration through the joints and the resulting expansion and corrosion will crack the terracotta or faience blocks and lead to still more decay. Injection resins behind the face can fill the voids, strengthen the mortar fill, re-bond the blocks, and often save costly cutting out and replacement.
The above techniques also apply to areas of stucco render. However, it is often the case that the backing substrate is of an unstable nature itself and these problems must be remedied prior to the restoration of the stucco.