Cavity wall ties, initially made from iron or steel, are prone to corrosion in damp conditions. To prevent this, they were galvanized with zinc. However, this protective layer can degrade over time, leading to failure. Pre-1981 wall ties often fail prematurely due to various factors such as corrosive mortars, exposure to rain, and substandard galvanizing. Fishtail wall ties expand upon corrosion, causing cracks in the outer leaf, while Wire Butterfly ties may snap without expansion, resulting in wall bulges. Replacement of older wall ties with modern stainless steel ones is recommended to prevent future failures.