Wall ties are unseen metal components that are built into the cavity walls. Their main aim is to enhance the safety and the stability of the cavity walls. A cavity wall has two parts, the inner leaf and the outer skin brickwork. The outer skin is very thick compared to its height. The inner skin benefits from the support offered by the ceiling and floor joists as well as the roof. The lateral restraint ensures that the inner skin is stable. Wall ties are metallic strips or bars that tie the inner leaf and the outer skin together. Wall ties help in transferring the stability of the inner leaf to the outer skin. In addition to stability, they are also made to prevent the transfer of water from the outer leaf to the inner one.
When the two are combined, a wall with greater thickness is formed. The materials used to make ties are flexible so as to allow the inner and outer parts to move differently when it is warm or cold.
Wall ties are usually made of steel though in modern times plastic is being introduced. In damp areas, they have to be galvanized to prevent corrosion. Stainless steel is preferred so as to prevent rust and chemical attack from cement.
Wall ties have to be handled properly to prevent failure. The requisite number should be installed and they should be bent at the mortar joint. Also high quality mortar is recommended to enhance the bond between the tie and the mortar.