All cavity walls have unseen metal components called wall ties. These are built into the wall are crucial to the stability and safety of cavity walls. Wall ties were introduced after World War I in construction to make them sturdier. Wall ties come as strips or bars of metal that span the cavity and tie the internal and external walls of bricks or blockwork together. The ends of the tie lock tightly into the mortar. The ties keep dampness away from the inner leaf of the wall. Steel and iron are the most common metals used to make wall ties. Stainless steel ties limit the risk of exposure to water and chemical attack when it comes in contact with cement.
Wall Ties are an important part of masonry, giving stability and protection to cavity walls. They are mainly used to support the inner skin wall, which is generally weaker than the outer skin. Wall ties are placed horizontally and vertically at uniform levels and lock the two walls. They span the length of the cavity and have their ends fixed into the concrete end of the walls. Basically, Wall ties affiliate the strength of the outer skin to the inner skin, increasing the wall’s stability for years. Lack of ties or badly placed ones can weaken a structure, causing several problems including cracks, the collapse of masonry and even water seepage.
Since walls are usually made of bricks, Wall Ties are also known as 'Brick' Ties or as the case may be with concrete walls as 'block ties. When ties are used to bind a 'block' wall to a 'brick' one, they are installed at the time of construction or after the inner skin has come up. Besides existing walls, ties are also extremely useful while building new walls along with older ones. In such cases, these ties are known as Wall Starters. There are multiple elements in a wall starter, which are decided as per the particular case and may include fixing strips, washers, screws, as well as Wall Ties.
Screw Tie – for joining two masonry walls or a masonry wall to a timber one
Timber Tie –for wood-based walls
Lightweight Ties – metal ties with plastic clips that keep insulation sheets in place.
Wall ties can also be customized for specific purposes, such as Acoustical to minimize external noise and Remedial, which are used to repair damaged ties in old buildings. Corrosion has been a major issue for ties made from mild steel, which is coated with zinc or paint. Heat causes this paint film to corrode and this accelerates structural damage. In such cases, bespoke wall ties are customized to repair and restrain the damaged walls.
Modern Wall ties are fabricated with the latest technology from metals, plastic and even composite materials that have value-added properties. They can prevent seepage of moisture and are even flexible to withstand expansion due to heat.