Crumbling external render at the base of a wall nearly always tells the same story: water rises, evaporates at the outer face and leaves its salts.

Rising damp height often surprises owners. Some walls stop at thirty centimetres, others climb well past a metre. Here is what sets that limit.

Loose wall tiles at the base worry owners, yet the fault rarely lies with the fixing. Water held in the masonry pushes from behind.