Vapour barrier sales will expand through 2036, with membranes at 56.1% of the material category and insulation at 40.0% of application demand in 2026. The market is estimated at USD 13.1 billion in 2026, is projected to reach USD 20.9 billion by 2036 and is forecast to record a 4.8% CAGR between 2026 and 2036.