Cavity Wall Tie Failure
As winter storms batter our coastal regions, older properties can suffer from the loss of gable end brickwork caused by a lack of stability due to cavity wall tie failure.
Since the Victorian era up to the present day, the building of two brickwork leaves with a small cavity in the middle has been the traditional construction method of choice for residential property in the UK. The idea is to stop damp transferring from the outer skin to the inner one and to provide a thermal barrier between the two skins.
To provide stability, the two brickwork leaves are bonded together at regular intervals during construction using ties, often made from metal or wire. Unfortunately, properties built before 1981 often used cavity wall ties either without any galvanizing or with limited protection against corrosion.
Once oxidization of the ties happens, the metal expands and can cause horizontal cracking to the mortar joints and bulging of the outer wall. The ties then lose their effectiveness which, in the worst case scenario, can lead to partial collapse of the outer leaf during wind storms, particularly to vulnerable gable ends.
An experienced surveyor can spot the tell-tale signs of cavity wall tie failure and recommend remedial treatments which can include the installation of replacement ties or even the full rebuilding of the outer brickwork skin, depending on the severity of the defect.
Blog provided by Tim Wells (MRICS)