Technical Booklet D Structure·Page 67·4C.11
Cavity wall ties - material and compliance
Cavity wall ties must comply with specific British Standards and be made of austenitic stainless steel material references as specified in BS EN 845-1.
The cavity wall ties should comply with BS EN 845 -1 and DD 140 2 and should be material references 1 or 3 in BS EN 845 -1: Table A.1, austenitic stainless steel. Wall ties should be selected in accordance with Table 4C.5.
Source — /Users/richardhill/Documents/planning-arch-project/data/documents/regional/Technical Booklet D - Structure.pdf