Brick can be one of the most durable building materials, as testified by the survival of notable Roman examples. Not infrequently, however, poor repairs, a lack of maintenance and inappropriate alterations lead to trouble.
Serious decay of mortar joints, and possibly bricks, because of continuous saturation (caused, for example, by leaking gutters) or salt crystallisation;
Crumbling ('spalling') of brick faces due to frost action, particularly on parapets or chimney stacks, or the use of a cement mortar rather than a lime-based one;
Cracking or bulging of brickwork caused by, for instance, tree root damage, rotten timber lintels over windows and doors or removal of load-bearing walls internally.