Lately, at Pure Maintenance we have seen an increasing number of mold issues actually caused by plastic vapor barriers. Often home builders will place a sheet of plastic over fiber glass insulation within the walls of a home. The idea being that the vapor barrier will prevent moisture from going through the sheet rock and getting into porous
framework and insulation. If moisture was able to make it through the sheetrock but was unable to evaporate naturally, mold would grow rapidly. The idea of the vapor barrier is sound, however if the vapor barrier is installed incorrectly, it can cause way more problems that it could ever prevent.
If a vapor barrier is placed on framed wood that has been rained on or that has gotten wet, serious mold issues will invariably follow. If the area behind the plastic is not 100% dry when the plastic is stapled to the framework of the home mold will slowly start to grow behind the homes sheet rock. It is like creating a giant petri dish of fungus. Once the mold gets to extreme levels behind your walls, you may start to see walls bulging in some areas. Eventually light weight microscopic mold spores will find their way outside the plastic and into your home causing serious health issues.
If you decide to use a vapor barrier in your new construction, be very careful to insure the framework and insulation are 100% dry and have no potential to become wet due to plumbing leaks, and floods. It could cost you thousands in cleanup costs.