Damp from the Ground Up: The Dirty Truth About Rising Damp Many Nigerian homes suffer from wet patches starting from the base of the wall. This is rising damp — ground moisture moving upward. Why it happens: No damp proof course (DPC) installed Nylon used as DPM tears during construction Capillary action allows water to travel upward Signs: Salt deposits (white powder) on walls Swollen skirting boards or wood damage Proper Fix: Injection damp proofing systems Reapplying DPM with a cementitious or liquid membrane Replastering with waterproof additive.