Cavity Wall Ties Replacement

Cavity walls are formed by two layers of masonry with a gap inbetween and cavity wall ties are used to help hold the inner and outer leafs of masonry in place. Cavity wall ties have been used as part of building construction to hold the inner and outer leafs of a wall together since around 1850. Without cavity wall ties, the increasing weight of masonry above would cause the two leafs to move apart. Over time corrosion and age can cause cavity wall ties to deteriorate and snap, resulting in severe structural damage to the external walls.

If corroded wall ties are left untreated, the masonry can bulge or crack and, in some cases, the building becomes unstable. It is not uncommon for entire developments to have the same problem, as all properties would be built at the same time using the same ties. It is essential to address any signs of cavity wall tie corrosion with a specialist surveyor and carry out any cavity wall tie replacement.

If you believe your property may require cavity wall tie replacement or you are concerned about the stability of your property, speak to a member of our expert team at Rentokil Property Care. Complete our online contact form below and a member of our team will be in touch.

Cavity wall ties are long strips of iron or steel (fishtail ties) that are placed into the cavity wall during construction and bridge the cavity to hold the inner and outer walls together. From the early 1920s, the twisted wire Butterfly tie started to be used.

Placed horizontally between the two walls and secured in place with mortar wall ties strengthen the wall. Their design prevents moisture running from the exterior wall to the interior wall and are essential to the safety and stability of the wall. Without wall ties or with ones which are corroded, large sections of brickwork such as gables can be affected by wind suction and face collapse.

Cavity wall ties were initially made from iron or steel, however, under damp conditions, both iron and steel corrode. To prevent deterioration, wall ties were galvanised with a protective zinc coating. Over time, the galvanised protective layer can break down, leading to wall tie failure. It was not till 1945 when the first British standard wall tie with a defined zinc coating was introduced and improved in 1981.

Cavity wall ties produced before 1981 have a history of premature failure and every year many homes across the UK suffer from cavity wall tie corrosion as a result of corrosive (black ash) mortars, permeable lime mortars, exposure to wind-driven rain, coastal locations, substandard galvanising on the tie and, on some of the early cavity wall ties, no protection from corrosion.

When fishtail wall ties corrode, they start to expand in size, forcing the outer leaf to crack along the mortar joint. Wire Butterfly ties tend to corrode and snap without expanding, so the first sign of a problem may be bulging in the wall. Most Butterfly wall ties are expected to have a design life of around 35 years but this can be much less in certain conditions. Properties built before 1981 could require cavity wall tie replacement with new wall ties. The process to replace wall ties requires specialist expertise, so it is recommended this is done by a professional.

To avoid wall tie failure in modern building construction and reduce the need to replace cavity wall ties in the future, wall ties are made from stainless steel to prevent corrosion.