Before getting into greater detail, there can sometimes be an indication, if properly understood that the building insulation is compromised, even when observed from the inside of that “wonderful” vapour barrier. A student related a phenomenon that was causing concern in his apartment; after putting the heat down at night, he noticed in the morning condensation inside his bedroom along the bottom few feet (60cm) of the outside wall. Well this was an interesting observation, that indicated to me that the moist air within the building became super saturated after the heating was lowered, to then condense excess moisture out onto the coolest surface. In other words, that bottom part of the wall was cold below a line of demarcation (the bottom few feet along the wall) indicating that the lower part of the insulation was failing most probably because it was wet below this line. It also indicated that the lower part of the building wall framing was probably wet and could be rotting away as well. Unfortunately, the wick-like behavior (like the wick in an old-fashioned oil lamp) of batt type insulation spreads and retains water beyond the actual lower saturated part of the wall. Later it became obvious that this was not some isolated phenomena when Metro Vancouver, on Canada’s west coast, began to look like a Shanty town of “Leaking Condominiums” draped in plastic. Yet, this was not just a Canadian problem, for after the energy crises of the early seventies, all sorts of odd “bits and pieces” were added to prevent heat loss in many countries, to mostly end in the detrimental sealing up of water within the exterior wall insulation between wooden framing members.
One indication of wet insulation
