R. C. DE VEKEY and W. J. REED Building Research Establishment, Garston, Watford, UK
Until recently virtually all cavity wall ties were of three types: (1) the butterfly wire, (2) the double triangle and (3) the vertical twist. Other patterns, such as the dovetail/slot, were used mainly for specialized cladding applications. Now a need for greater durability has led to new stainless steel designs. In order to develop more comprehensive standards for ties, previous data on performance have been reviewed and the results of recent investigations are reported including data on one newer type of tie. The experimental work includes an evaluation of alternative test methods and their sensitivity to tie design and other variables such as mortar properties.