We recommend that you test the strength of the substrate before selecting an appropriate size of drill bit to drill the insertion hole.
Ideally, tests need to be carried out on site by conducting pull out tests to determine the size of tie and pilot hole required to comply with the specification.
Alternatively the following sized pilot holes can be drilled (prior to the insertion of the wall tie using the BrickFix DriveTie Fixing Tool) following a visual survey to assess suitability:
5mm for 7mm helical wall tiles
5.5 - 6.5mm for 8mm helical wall tiles
6 - 7mm for 9mm helical wall tiles
Which size drill bit do I need to use for BrickFix Wall Ties?