Quote:
Originally Posted by UFO
Having lived through a full envelope restoration at our old building built in the mid 90's, even top notch craftsmanship and materials would have led to the same leaking issues -- as I unserstand the issue was with the building code itself at the time. The building boom, crappy materials and workmanship, really are secondary issues.
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What caused the leaky condo crises was a variety of factors.
But the ultimate root cause of it was this:
The building code was becoming more stringent on energy conservation and building insulation. As a result builders began insulating their buildings more than before. This resulted in less heat escaping through the building envelope and drying the moisture ingress in behind the cladding. This is where you would start to see rot, mold and other building envelope failures common with a "leaky condo".
Put simply: Prior to the leaky condo crises buildings had the same leaking issues, however they lost so much heat through the building envelope that it wasn't a big deal, the heat loss would dry the materials prolonging the issue for decades. Following a building code change to require more air tight, and heat tight buildings, builders continued building with the same construction style except with more insulation which reduced that heat loss through the building envelope. So that moisture would get trapped and no longer got dried by the heat from the inside of the building.
Following the leaky condo crises, buildings are now typically built with what is referred to as a "rain screen". This is a 2 layer system which protects the building from moisture ingress. This is typically a cladding layer, with a strapping layer holding it ~1" off of a moisture barrier type material. The cladding being your primary protection and moisture barrier being your secondary line of defense. Coupling that with a vapour barrier which follows the insulation of a house, you've triple sealed the building from traditional "leaky condo" issues.