The exterior walls of most twentieth and twenty first century buildings consist of two parallel leaves of brick or block work approximately 50mm apart. Metal wall ties hold these wall leaves together. Metal wall ties were initially made of either wrought iron or mild steel without any rust protection and it was not until later that galvanised steel tiles became the norm. Even then, the quality of galvanising was extremely variable and thus, in houses built before World War 2, it is quite common to find that the wall ties have corroded.
Wall Tie failure can produce a variety of symptoms depending on the type of tie, mortar, brickwork etc. Look for regular horizontal cracking, increasing towards the top of the building at every 4 or 5 courses.
In most instances, wall tie inspections can be carried out by Insitu SCP staff with a minimum of disruption and, where necessary, new stainless steel wall ties can quickly be inserted in place of the corroded ones.