I agree with Happy Strata.
Our scheme requires a pre-installation test to guide choice in the type of materials suitable to reach LnTw set in by-law (40 in our case) and then a post-installation test to confirm correct installation.
After 12 months of following this criteria we now have data from about 15 units – each with varying base (concrete slab) readings. Two units had base readings were so high (70+) that the engineers advised no hope of achieving a satisfactory outcome no matter the materials used.
Those that had more moderate readings (<70) have had fabulous outcomes.