I have a suspended floor in my 1960s house. I am going to struggle to get all of the floorboards up and down again to install PIR between the joists and cannot afford to pay for this to be done. Is it possible to do a floating PIR floor at 50mm and then put a 9mm ply on top in order to do glue down LVT flooring? Changing all the doors etc anyways so that isn't a problem. Thanks!