Soundproofing is a legal requirement in flats.
The product we usually use is Polyethylene Sound Reducing Mat (3mm or 5mm thickness), dB rating – 18 dB (3mm thickness) and 24 db (5mm thickness), Tog rating – 0.4. This particular Silent Blanket allows us to glue the floor boards directly to the subfloor, through specially done holes, creating solid and firm feelings under your feet. The adhesive we are using in combination with the Sound Proof Blanket is playing a role of sound insulator too. It is one component, solvent free, silane based adhesive that remains permanently elastic, keeping the grip, but on the same time allowing that slow motion movements of shrinking and expanding that all wooden floors do (to be done nice and smoothly). Here are some pictures of the installation process.