The subject buildings form an estate of terraced and semi-detached social street housing of cavity construction under pitched roofs.
The existing wall ties viewed were found to be mild steel vertical twist ties, commonly known as fishtail ties. The galvanised coating was found to be in varying stages of corrosion, blackened with red rusting noted.
The corrosion of the embedded mild steel wall ties had resulted in the formation of ferrous oxide, which had expanded to many times its original thickness lifting and cracking the brickwork.
An archetypical example of a wall with the symptoms of expansive corroding wall ties lifting the bricks cracking the bed joint horizontally that has simply been re-pointed. This action has only temporarily addressed the symptoms and NOT the causation.
AWT completed a remedial programme providing a comprehensive repair through the introduction of a pattern of remedial wall ties and isolating the existing ties, together with general brickwork repairs and re-pointing.