When talking to people that are in the business of fixing crawlspace issues, it is important to first understand that there are no real places for people in this industry to learn, train, get certified or really just find out real information that is not just from the sales pages of their websites or sales brochures. The best example of this is the not so simple task of learning why you even have foundation vents on your home.  when asking what to do with them, you get a full round house of confusing answers: “You should close them in the winter and open them in the summer”…. “Close them in the summer and, well, close them other times as well”….. ” open them in the winter and spring then close them during the summer”.  Why all the conflicting answers? Because the majority of the industry thinks about foundation vents in terms of moisture control for your crawlspace or even in terms of energy savings in the winter. The truth is, the foundation vents were put on your home because the air under your home is thick with contaminates that you don’t want to breath. Mold and fungal spores, radon, methane, ammonia and other air contaminates that the SOIL creates every day. Yes, the soil! Way back in 1800’s early 1900’s builders knew that the soil made for very unhealthy air and an open foundation was important to encourage clean air exchange and minimize the impact of the soil on the indoor air. These days, people equate mold that you may breath in your home with mold you see growing on the wood in your crawlspace. If you are lucky enough to have clean, mold free wood in your crawlspace, you might feel good that the air in your home will be better for it… but that is not really the case.

Since 2009, HHR has been conducting a study on the effect of the different crawlspace systems in NC on the air quality in the home. The results have been surprising to say the least. The goal was to stop relying on urban myth and sales brochures when understanding crawlspaces, moisture and mold problems. One of the basic and most important findings from this study is, the soil is the overwhelming contributor to the mold spore count in the air of a crawlspace and ultimately, in you homes air. In air samples taken in the crawlspace of over 30 homes with open foundation vents and a normal vapor barrier, the average spore count for mold was at 8000 spores per cubic meter of air (spores m3). Air samples taken in a crawlspace before and after mold remediation showed almost no impact in the spore count for the crawlspace since only the wood was addressed and the dirt is always ignored. Turns out, the mold you see growing on the wood of your crawlspace is putting out mold spores in the air but only at a tiny fraction of the amount of mold that the damp soil under the vapor barrier is creating on a constant bases, day in and day out. The foundation vents you may have are important in order to let out the bad air and allow clean air back into the space for good air exchange to help minimize the crawlspaces impact on your indoor air you breath.

The crawlspaces in this area bring about a very confusing array of catch 22’s. These can be discussed in detail in other articles on our site, but I will try to list each catch 22 with the associated crawlspace feature. For instance, the foundation vents are there for air quality to try and avoid the extreme buildup of mold spores, gases and other contaminates that come from the damp soil under the home that never gets any sunlight. Open foundation vents can be a problem for excess humidity during humid seasons and cause mold to grow on the wood. So how do you close the vents to prevent a humidity problem without creating a larger indoor air quality issue? It can be quite the confusing mystery! (Don’t worry, the issue is solved by our ongoing study and our unique SCV system)

This brings up another crawlspace standard items and the next catch 22. The vapor barrier. The goal of the vapor barrier is to minimize the damp soils impact on the humidity under the home so that you are less likely to have wet wood and mold growth on the wood. For this purpose, the vapor barrier can work! Unfortunately, it does not always work and in some cases will actually make the humidity worse. If your humidity problem is only related to very damp soil, then the vapor barrier will work to help. If your humidity issue is related to poorly ventilated or under-ventilated crawlspaces and the dirt happens to be fairly dry, then your new vapor barrier may make the humidity worse in the space by catching the water droplets from condensate and creating large puddles all over the vapor barrier. These puddles will now turn your crawlspace into a wet moldy mess and it will be the vapor barriers fault! The second problem that can come from a vapor barrier is, when you place plastic on the soil, it traps the moisture in the soil which creates a damp, anaerobic space that actually encourages more mold and bacteria growth causing the air under your home to have even higher concentrations of mold spores in the air. Yes, the vapor barrier can help control humidity in many causes helping to keep the wood under your home dry with less visible mold growth but the actual count of mold spores in the air that you breath will be higher. In our study we found that normal ventilated crawlspaces that had some lite but visible mold growth on the wood but had no vapor barrier, averaged 5000 spores m3. For ventilated crawlspaces with the same level of visible mold growing on the wood but have a good vapor barrier installed, the mold count actually went up to 8000 spores m3! The irony is, most people install a vapor barrier to help prevent mold from growing on the wood under their home but end up increasing the amount of mold spores that are in the air under the home! That is the second crawlspace catch 22 you have to contend with while trying to understand the healthy, dry crawlspace.

This brings up the last crawlspace basic we will discuss in this article. The “Sealed” vapor barrier. When looking at encapsulating, closing or sealing up your crawlspace, the technique will include a thicker, higher quality vapor barrier that is sealed at the seams and generally wrapped around the foundation piers and installed up the foundation walls to seal off the moisture from the soil and help with keeping the space dry. The idea that this sealed vapor barrier is actually sealed turns out to be one of the most disturbing urban myths! There is no practical way to take a sheet of plastic, a pair of scissors, some tape and caulk into a dirt crawlspace with uneven floors, rough concrete surfaces and porous concrete block foundation, and end up with a perfectly sealed vapor barrier. Even if the installer did an excellent job actually came pretty close sealing it airtight, do you think it will still be sealed after a few years of plumbers, termite contractors and HVAC workers all visiting and crawling around under the home?  the idea that you are going to have a sealed vapor barrier installed that will forever block mold spores, gases and radon from getting into the air of the crawlspace is also an urban myth.

With a “sealed”(ish) vapor barrier, what you have actually created is a perfect breeding ground for molds, fungi and bacteria and the resultant unhealthy air they create sneaks through the imperfections of that vapor barrier and into the air under your home.  Where it really becomes a problem is that now, with these sealed vapor barriers, they also seal up the foundation vents nice and tight and eliminate any chance for fresh air exchange. In our study, we have tested over 80 sealed and clean crawlspaces with sealed vapor barriers, no visible mold growth on the wood, low humidity and it would pass a visual inspection by a home inspector. In these air samples, the clean, “Healthy” sealed crawlspace ended up having the highest amounts of mold spores in the air at 22,000 spores m3!  Turns out, the unhealthiest way to build a home in NC is the home where the crawlspace under your home is sealed and done by professionals at current NC building standards! This is why it is so important to understand how our research and inclusion of our unique HHR method has fixed these issues to create healthy homes.

To summaries the three urban myths:

  1. The foundation vents are there to help control moisture. (MYTH). Truth; they are there to promote clean air exchange to help prevent the unhealthy buildup of soil related contaminates/ pollutants in your air.
  2. The vapor barrier is needed to prevent moisture issues. (Myth). Truth: the vapor barrier can help in some cases but may hurt in other situations and actually encourages higher mold spore production in the soil.
  3. A sealed vapor barrier is actually sealed. (Myth). Truth: It is not practical or really even possible to install a perfectly sealed vapor barrier in the environment under your home and when you combine that with the permanently sealed foundation vents, it becomes the least healthy way to have a crawlspace no matter how big the dehumidifier you install or any other method used to keep the air dry.
  4. This brings up the fourth urban myth. A clean, dry crawlspace with no visible mold growth on the wood, is a healthy crawlspace (Myth). Truth: the dirt under your home will always grow molds bacteria, fungi and produce things that create very unhealthy air. The vapor barrier actually encourages higher levels of these pollutants and even protects the soil from the dehumidifier that is working hard to keep the wood dry and prevent all of these mold spores from growing! Add that to the painful fact that there is no such thing as a sealed vapor barrier and you start to understand the challenges.

The main problem with the crawlspace industry in our state and this region is the lack of any training, published studies and the persistence of these urban myths. As long as people continue to spread and believe the urban myths and do not have access to proper training, the common techniques for fixing moisture problems under homes will continue to create the issues with unhealthy homes while costing homeowners thousands in repairs.

At HHR we solved that issue long ago and have been validating the results with ongoing air quality testing and research since 2009 with experience in these issues going back to 2004! For more information we encourage you to contact us for a free inspection and consultation covering every aspect of indoor air quality in, under and around your home.