An underlayment for supplementing one or more physical properties of wall, ceiling, and floor construction components is used to in a wall, ceiling, or floor assembly that may be fabricated on site. The assembly includes: first and second wall, ceiling, or floor construction components which each have physical properties and an underlayment component which has at least one supplemental physical property for supplementing the physical properties of the first and second construction components. The construction components may or may not be secured together with the underlayment sandwiched between the second and first construction components to form a wall, ceiling, or floor assembly with the supplemental physical property or properties of the underlayment. The supplemental physical property or properties of the underlayment may include, but are not limited to, latent storage of thermal energy, sound transmission reduction, and/or burn through resistance.