Crawl space ventilation is the most critical part of handling the crawl space moisture problem. It is not the only part, but the one that will affect the quality of air that is in your home. You have to get this part right or the current situation will likely worsen. A home, a cottage or any building that is closed up without air circulation will smell stale. It is not an uncommon practice to “air out” a summer cottage that has been closed up for the winter. The process of airing out is simply circulating the air inside the cottage; exchanging the old stale air with new fresh air. The more air that is exchanged the fresher the smell. This air exchange is also required for a crawl space. Really, that is what the foundation vents are supposed to do. When you look at the current condition of the crawl space, most often it will need a steady supply of fresh air. We already went through the negative issues with exchanging the crawl space air with the outdoor air. So, how does the crawl space get fresh air if bringing in outside air is bad? First, I want to make sure my view on this subject is clear. I am a huge advocate of bringing in fresh air from the outside into the home. Open the windows when the temperature is comfortable, air out your home regularly. Fresh outdoor air is great for your health. How does this help or hurt the conditions in the crawl space. Well, the most important thing you can do to properly assess and make good decisions about air exchanges in your home is to stop separating your home into different parts when you are considering an air circulation plan. Since the time your home was built the crawl space was not considered part of the home, its time to change that! Whether you like it or not a large amount of the air in the crawl space makes its way into your home. Every tactic we have used in the past has failed to impact this particular problem. The odor you smell, the condensation on the windows and the allergy symptoms all remind us that there is something going on in the crawl space. Simply put, we experience at least some of the conditions from the crawl space inside our home. The more serious the condition the more motivated we are to getting it fixed. Living with the more serious condition from the crawl space making its way into the home, the last thing anyone wants is to circulate that air freely into the home. That would make it much, much worse. Right?! This probably is the most successful “pitch” the companies that sell the mechanical vents can use. Their mantra can be “don’t let the crawl space air into your home”. If the goal is to allow the crawl space to exist as is, then of course that would be a good plan, provided you are willing to use the conditioned air in your home that you paid for to fuel the plan and are willing to accept the other flaws. There is a better way, I want to give you some more information first so that you fully understand the decision you are making.