Ensure your subfloor is clean dry and most importantly level ready to receive the flooring. Install dB Matting 15 over your level subfloor. DB Matting is installed in a brick bond pattern, bond down to the subfloor using Mapei Elastorapid VS90 or F3 adhesive, apply the adhesive with a 3mm notched trowel and lay the dB Matting over the adhesive. Install the dB Matting tightly to the walls at the perimeter of each room. If there are any gaps around the wall infill with acoustic sealant.
Install the Unifloor Jumpax Heatpak over the dB Matting 15 (see full Jumpax instruction here). The 3mm baseboard is installed first 'tacky' side up, then the 4mm top board is cross-staggered over the baseboards, peeling away the film to lay on its self-adhesive back. Leave a 5mm expansion gap around the perimeter of the jumpax and infill with an acoustic sealant. The Jumpax creates a cross-braced level solid floor with minimal deflection to receive your LVT floor finish. It also provides an MDF surface for the LVT to be bonded to or laid on.