Timber frame structures in particular are largely affected by moisture build-up. Due to timber's hygroscopic nature, any moisture from humidity and condensation will be absorbed by the timber structure. This absorption of water massively increases the chance of rot, and in turn, a loss of structural integrity.  What's more, damp and lack of vapour control foster the growth of mould and mildew. Mould can greatly affect the health of building occupants, causing a whole range of issues from respiratory complications to lung inflammation; a particularly grave risk for those with asthma and pre-existing health conditions.