Table 2Critical relative humidity for various groups of materials

Material groupRelative humidity (%)
Wood and wood-based materials75–80
Paper on plasterboard80–85
Mineral insulation materials90–95
Extruded and expanded polystyrene90–95

From: 3, Moisture control and ventilation

Cover of WHO Guidelines for Indoor Air Quality
WHO Guidelines for Indoor Air Quality: Dampness and Mould.
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