Essay:
Moisture problems in buildings
Construction is a huge industry, total construction in US 1997 is $577 billion. Moisture related building envelope problems C-1 have draw everyone's attention in recent years.
In Canada, the BC condomium (related info: B.C. moisture problems - phase II, building science was blamed by Barrett for BC building failures, Vancouver building problems, findings).
Biodeterioration is the main mechnism of bulding envelope damage. The moisture accumulation in the envelope due to moisture migration through building envelope and moisture transport in porous materials by way of condensation and interstial condensation.
Molds and fungi are the main type of biodeterioration, among others: termite cause property damage to $1 billion a year in 14 US state. The exact mechanisms are still to be studied, mold: growth model is imerging to predict the occurance and damage of molds. The mold: health effects have been investigated, yet much research is needed.
Among cladding systems, EIFS seems have great problems: Synthetic Stucco EIFS Litigation, EIFS damage, EIFS, as well as the above Vancouver B.C. problem.
Wood is a common building envelope materials in Canada and other countries in wood frame houses and walls, especially of the residential area. (Wood facts by CWC, wood decay and water is directly related, wood destroying insects causing damage to $5 billion a year., Wood Durability, Wood finishing at FPL, USDA, wood thermal conductivity vary with temperature).
One of the moisture control strategy is the use of vapor barrier, vapor retarder (vapor barrier is necessary to reduce moisture diffusion through envelope, vapor barrier during roof renovation, vapor barrier classification). A new trend in vapor barrier is the smart vapor barrier / smart vapor retarder. Moisture Control Strategies Presently Employed.
A a good non technical manual on Moisture and air: problems and remedies is provided by CMHC.
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