An assembly insole impermeable to water and permeable to water vapor, with a structure including a membrane impermeable to water and permeable to water vapor and arranged in an upward region, and a supporting layer arranged below the membrane, made of a material resistant to hydrolysis and vapor-permeable or diffusely perforated, and capable of acting as a support for the foot, as a manufacturing base for the shoe, as an element for protecting the membrane against the penetration of blunt objects, and of withstanding the stresses induced in the shoe during use. The membrane and the supporting layer are mutually joined so as to make, as a whole, the assembly insole impermeable to the passage of water and not compromise the vapor permeability of the membrane.