What are wall ties?
In a cavity wall, there are two thin skins of masonry. Older houses have two skins of brickwork, more modern houses a skin of brickwork and a skin of blockwork. The two skins need to be tied together to give the wall structural integrity. The ties should be positioned at 900mm centres horizontally and 450mm centres vertically. The ties themselves were made from iron in early times and then out of galvanised steel. Corrosion of the ties has become apparent as have problems with an inadequate number of ties. Modern ties do not corrode, they can be made of stainless steel and plastic. If there are insufficient ties or the ties have corroded, the wall becomes unstable and often cracks and bulges. The damage can look like foundation movement but is unrelated to the foundation.
