At the viewing · claim and test

Four things you may hear about a damp patch

Each can be true. Each can be tested before the CPCV.

Seller

"It's only condensation."

Test it with
  • Position: cold corners, ceiling strip, window border
  • Diffuse black spotting, sound plaster
  • Present with cold nights, rain or no rain
Seller

"The leak was fixed last year."

Test it with
  • A dated invoice naming the work
  • The source: roof, terrace, window, neighbour
  • Condominium minutes if a common part was involved
  • The stain after heavy rain
Agent

"Every older flat has some damp."

Test it with
  • 32.1% of the population lived with damp or infiltrations in 2025 (INE)
  • This flat's windows, insulation and roof above
Seller

"Air the flat and it goes away."

Test it with
  • Does the pattern fade after airing and heating?
  • Salts or blistered paint under the mold point to water in the wall
InspectOS · Sources: INE, Rendimento e Condições de Vida 2025 (11 Dec 2025) · Mixed causes confirmed on site with thermal imaging and hygrometer in a Moisture Inspection · Updated October 2026