Cold Air Coming Soon! Do I Open or Close my Crawl-Space Vents?

Summer vents open & winter vents closed, right? Or is it… closed all the time?

Based on a little research, the answer could be yes to either of the above. You ask, “how is that possible? There has to be a simple answer to this simple question.”

There are three main areas to investigate when it comes to leaving your vents open or closed and they might all be interconnected:

  1.  Moisture levels
  2.  Heating and cooling cost
  3.  Entrance for termites and other critters

If you are having a moisture problem it is likely because your crawl-space is cool and the warm moist air in the summer is attracted to your cool crawl space (warm air flows to cold air). In this case you might want to consider closing your vents or even blocking them off completely with foam blocks that are specifically made for this purpose. This tends to be the most common solution in the warm-moist areas of southwest Missouri. In the winter, closing your vents is almost always the solution as you do not want the cold air to slip into the crawl-space of your home.

But, this is not an open and closed case. It honestly comes down to you doing a little investigation on how your home is setup and how it reacts to your vents being open or closed. Do you have a dirt floor, concrete floor, moisture barrier, gravel floor, A/C vent leaks or some variation? The way your crawl-space is constructed can greatly impact the moisture levels.

The best way for you to see how your crawl-space is reacting to the ventilation is to place a weather gauge sensor in your crawl-space with a wireless display inside your home. Try it with the vents closed and with the vents open and maybe even try it with styrofoam blocking them completely. If you do this experiment be sure that you are comparing levels while the conditions are the same outside. This could take some time to get it figured out or it could be obvious quickly.

If you have a moisture issue, pest issue or heating and cooling problem, CONTACT AN EXPERT. It might not be as simple as when to open and close your crawl-space vents.