The pug mix acts as a sound and heat insulation when laid dry mix ,it takes low frequency noise , laying it wet stops it being a sound barrier and reduces the thermal insulation , I would say it is a bad idea , top post from Julian there
Yes, one reason for using pug mix instead of alternatives, e.g. spreader plates, is that it gives some acoustic insulation from the floor below for airborne noise. We are laying it damp now, not wet like mortar. But why would laying it wet reduce its sound barrier properties -- I thought the barrier to airborne noise depended mainly on the mass of the barrier, so there would be no difference, wet or dry, once cured?
Also, why would laying it wet "reduce the thermal insulation"? Anyway we don't mind the thermal insulation being reduced -- the less the thermal insulation, the more easily the heat will come through.
In the bathrooms we may have ceramic floor tiles, maybe on 6mm thick cement backer board to make up the levels to the bedrooms. The combination will have good thermal conductivity, particularly important in the bathrooms
In the bedrooms we intend to use 14mm thick engineered timber flooring. Between the engineered timber and the structural CIPB floor we intend to lay 6mm thick iso sonic rubber matting to reduce impact noise.
Grateful for any more advice from anyone