This topic is one that is significantly misdiagnosed and misunderstood .

Photo 1 below shows an incidence of an obvious dampness ( in this instance attributable to various external defects allowing direct moisture penetration )

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Photo 2 below , shows both evidence of defective plasterwork ( attributable to rising dampness ) and also condensation mould growth ,  in this instance caused by an almost complete lack of ventilation to the room in question , together with intermittent heating.

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The following link explains the basic differences