Wall Tie Corrosion Treatment & Replacement
Wall ties are used to join the internal and external walls (or leafs) of a cavity wall and are installed during construction.
Over time these wall ties can corrode and require replacement – particularly where ungalvanised or inadequately protected steel wall ties have been used. The expansion caused by this type of corrosion can force apart mortar joints – causing cracking of masonry. Other symptoms include bulging of walls and the lifting of roof edges. In severe cases wall collapse has even been reported.
Wall tie corrosion is particularly common in buildings in coastal areas (due to salt-laden driving rain) and in masonry that has been constructed using corrosive black ash mortar. However because most buildings will outlast the life expectancy of the wall ties installed during construction, wall tie replacement will be necessary at some point for most buildings constructed using cavity walls.
Replacement of wall ties may also be necessary if the original wall ties used to construct a cavity wall were installed incorrectly – for example, where too few ties were installed (low tie density), where the wrong type of wall ties were used, or where site control during installation was poor.