Laying, with glue or dry, the new floor on top of the old flooring, without previously demolishing the latter, saves on costs and on the execution time of the renovation, and is in general a cleaner installation because it produces less rubble and less dirty in the house.
The thin porcelain stoneware floor is certainly the most resistant and suitable product for any room in the house, given the solidity that guarantees high resistance to shocks, scratches and humidity, even in the slim 3 mm or 5 mm version.