For best results, interior dampness has to be dealt with comprehensively. First all active sources of water like leaking/cracked pipes should be identified and fix. Cracks and gaps from adjoining walls such as kitchen, bathroom and terrace should be fixed. Finally, for heavy dampness, use products like Damp Block 2K, which come with the assurance of upto 3 years company backed warranty. If you’re getting your house painted and don’t see any major dampness, then use products like SmartCare waterproof putty and SmartCare Dampsheath Interiors. These are specially designed to keep dampness away and since they are used instead of ordinary primer and putty, these come with marginal incremental cost.