To prepare any space for humidity control, the choice of vapour barrier is based on the degree of dryness or RH.
Commercial vapour barriers – moisture resistant construction material, paints and other coating offer a variety of design alternatives. Manufactures of vapour barrier materials can supply specific information on their products.
Between 40 – 50% RH, special vapour barrier paints will provide an economical reduction in moisture ingress. Below 35% RH, it is recommended to prepare the conditioned space properly with good vapour barrier treatment including polythene etc. as an inside envelope for reducing the moisture load which has a significant effect on the sizing of the equipment.