• Insulation must be in contact with an air barrier.
  • This air barrier could be many things
    • Exterior sheathing
    • Vapour Retarder (Vapour Barrier)
    • Floor Sheathing in a floor system

Illustration Source: Summerhill

9.25.2.3.3) Except where the insulation provides the principle resistance to air leakage, thermal insulation shall be installed so that at least one face is in full and continuous contact with an element of low air permeance.