By now, most people have heard of the concept of a sealed or closed/ encapsulated crawlspace. There are many touted benefits of this popular project including moisture control, energy savings and even pest control for under the home. What people do not know is that there is a huge deficit in training and knowledge by the “Expert” installers of closed crawlspaces in the industry. Why this is important for a home owner is that there are many adverse consequences to a closed or sealed crawlspace based on how it is done and who is doing it. The statistics have never been complied but a good estimate one of the issues would be that 95% of crawlspaces that are closed or sealed up end up causing more indoor air quality problems than before even though the space is now dryer and the mold may have been cleaned or treated. I may need to repeat this statement one more time to let this fact sink in…. As much as 95% of all closed or sealed crawlspaces converted from a traditional foundation vented crawlspace will have worse air quality after the project than before any work to clean or close the space was done.
So how can this be so? The answer is much simpler than you may think. To start, there are many urban myths about crawlspaces that not only exist in the homeowner community but also persist in the contractor community. One of those myths is the operation of the foundation vents. You have all probably been told many different stories on what to do with these pesky foundation vents located all around your home for the crawlspace. Open them in the summer and close them in the winter….. wait, or is it, close them in the summer and open them in the winter,,, no hold on, close them all the time, or did the last guy say to open them all the time? I cant remember, so confusing! The reality is, foundation vents were not put on your home to aid in humidity control. In fact they are very bad at it. This is an urban myth that needs to be debunked. Each house is different and has many characteristics that affect the humidity in and under the home. A short list is, soil moisture, exterior grading, cleared lot or mature plant and tree growth, the amount of foundation vents, where they are located, the style of vent, the height of the crawlspace….etc. The bottom line is, it depends! Unfortunately that is the answer. For one home, based on the different characteristics described above, having the vents open all summer may work and that crawlspace is always clean and dry because of it. Then a neighbor hears this, opens his all summer and there is massive condensation and mold by the end of the season. Each different home has different needs for how the environment in the crawlspace is going to turn out. Foundation vents are put on a home to promote better air quality and prevent the build up or air contaminates under the home. For humidity control the answer is, it depends. For air quality, closed vents trap soil gases, fungus and mold spores not only from damp wood but also from the soil as well. Odors, dust mites, and other contaminates like rodent and insect feces and fiberglass particles are also an issue. The air under your home is full of things that you don’t want to breath, smell bad and can upset your allergies or even make you sick. The vents were put on your home to help let that bad air out and let clean air in so there is a constant clean air exchange to prevent toxic air buildup under the home.
Now with this unfortunate fact in mind, how can someone close up or seal you crawlspace and expect to improve air quality. Another issue that is a bit of an urban myth is the “sealed liner”. Unfortunately, there is no way to install a perfectly sealed liner under the home. Not when you are sealing around porous concrete block, using tape for the seams and your installers are already annoyed with the fact they they are working in confined, dirty space under a home! Over time there will be a build up of odors and air quality contaminates and soil gases that have no where to go but into your home slowly migrating through building materials. One confirmation of this problem is the issue with radon testing. Many homes are tested for radon when they are sold. The homes with open air vented crawlspaces will almost always (not always) test low on radon levels and happily pass for the excited buyers of their “new to them” home. If that home is later sealed to solve an issue with moisture and/ or mold and then years later the home is put back on the market. There is a much higher probability that the home will now fail the radon test and then the shocked owner will have to have costly radon remediation work done on the home before it can be sold. So what changed? The foundation vents that were letting radon out from under the home and letting fresh air in are now tightly sealed up and the space no longer breathes.
Healthy Home Restoration started out in the mold and indoor air quality business and migrated into converting crawlspaces to sealed crawlspaces many years ago. Early on In this process we noticed our air quality test showed higher (Much higher) levels of mold spores in the air in closed up spaces than before even though the space was very dry and had been cleaned and treated for mold. We also got many calls from people experiencing odor problems in the home after there space was sealed (By another contractor) and there installer could not figure out how to solve the issue so they found us to help. The answer to the radon, odor and air quality issue were the same in all cases. The space used to have a source of fresh air exchange with the open foundation vents and now, after it was converted to a sealed space, the air had become stagnant and filled with contaminates over time that had not way of being flushed out. A closed crawlspace needs a source of fresh air AND more importantly it needs a way to remove old contaminated air and better yet, prevent it from coming into the space in the first place.
Every sealed crawlspace we install is done using the highest quality materials with very experienced and meticulous installers but more importantly we make sure there is an air exchange system that is constantly ensuring the removal of contaminates, preventing entry of gases and odors and providing for good fresh air exchange. Healthy Home Restoration is unique in the industry with our goal of air improvement of the home and our systems for achieving it. The bottom line, you cannot close up a space that has a history of issues and damp soil, fungus, mold gases, critters, fiberglass and other indoor air contaminates and expect to have better air quality if you do not provide for a proper and effective air exchange system. Just blowing air from the HVAC ducting is not enough and just having an expensive crawlspace dehumidifier does not provide for fresh air and will drive the energy cost for your home up significantly.. You need to start with constantly removing the bad air and supply good air if you want long term healthy air for your home. We do not charge for our inspections so please call us today and we can come take a look at your home no matter if the space is already sealed or a foundation vented space.