Cavity walls have been a common feature of buildings in the UK for over one hundred years. Two leaves of brick or stonework are held together using metal straps or “wall ties”. The cavities between the two leaves of masonry provide an affective barrier to water penetration and also acts as an insulation layer.
In some circumstances these wall ties can corrode or fail. Failure can manifest itself as cracking in the external leaf of masonry, structural movement or in severe cases the collapse of sections of masonry.