Aluminized styrofoam; 2 sheets required. Home depot vinyl roll $50, oem plywood underneath (not fastened to anything), rivet holes in floor epoxied and caulked, fuel lift pump access door. Details in YouTube video below.
Foam underlay. Vinyl planks from Lowes over insulating foam underlay
Sound deadening material, then vinyl over polyiso board and insulating foam. We chose step trims and carpet trim to finish.
Rattle trap, timber strips, foam board, plywood, click vinyl flooring.
Vinyl over underlayment