Why do we care about condensation?

Here at Freedom Vans, many of our clients are based out of the Pacific Northwest and endure the consistent humidity and resulting van condensation, so much that we thought we would throw in our two cents into the collective internet knowledge. There are a lot of opinions and suggestions floating around the internet about the methods one should apply to battle condensation in van spaces. Suggestions range from exposing tea bags to the open air overnight, to- more seriously- spending the time to fully vapor barrier the interior. However, general consensus underscores the importance of addressing the problems of van interior condensation immediately, even before you move into your van. Think about it now before you’re sanding rust off of the edges of your snowboard, or finding speckles of mildew on your clothing. The bottom line is that we absolutely need to care about condensation because there is a connection between the metal of our vans and the vitality of our lungs: once compromised, both are irreplaceable.

Armchair Climatology: What is condensation?

Humidity of the inside of our vans is determined by the temperature. That is, warmer air can hold more water vapor than colder air can. Once humidity maxes out – ie absolute humidity, where the mass of water per unit volume of air reaches 100%- the air cannot hold anymore water vapor. Consider the winter day when you can see your own breath. Technical terms knows this as the dew point, but van-dwellers more closely know it as waking up to feeling damp and all of the windows are sweating.  If you have ever lived in a really cold place, that condensation freezes into ice on the insides of your windows, and good luck showing up to work on time. A typical winter evening for a PNW van dweller most likely begins as a moist one from the rain. The temperatures have not peaked over 7 degrees Celsius – reaching 100% humidity very quickly. When we factor in our average volume of water vapor that we exhale (over 1 pint) and the moisture from precipitation that we have collected on our jackets throughout the day, we can very quickly understand how much moisture we are contributing to the humidity inside of our vans.

Figuring out the relative humidity of our vans in the PNW

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The RH value is given in percentages and is “the ratio of the partial pressure of water vapor to the equilibrium vapor pressure of water at a given temperature.” (Wiki: Relative Humidity) The right axis denotes the temperature in Celsius. The bottom Y-axis denotes the mixing ratio between the RH value and temperature.

For those who love graphs and numbers, I used an online calculator to figure out the mixing ratio for breath condensation for a blustery winter Bellingham winter night (at 0 degrees Celsius). Note that this does not factor in the wet clothes that I had just mentioned. See inserted graph and values below. In general, the lower the mixing ratio, the easier it is for your breath to condensate. Look how tiny that blue line is over in the left corner. We can therefore deduce that it takes almost no time for condensation to start forming under these conditions.   Consider the variable that we are effectively raising the overall temperature of the van’s interior simply by being in it. If I raise the temperature from 0 degree Celsius to 3 degrees Celsius for the final temperature of the inside of the van, that blue line is still tiny. Therefore, adding the variable of our body heat into the function is important to consider but if our primary concern is our comfort and keeping the edges of our snowboards rust-free, then it really doesn’t add any weight due to the outside humidity. But we love living here, so what should we do?


Our Suggestions in Tackling the Condensation Issues 

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Okay, we have defined what condensation is, where it might be coming from, and why we need to care about it. Let’s talk about what we can do to mitigate the problem so we can prevent the rapid spread of unchecked mildew and/or rust. We understand that you may not need to go to such lengths to address the problems of humidity in your van if you live somewhere warmer and drier. That being said, we highly recommend adopting most of these features if you live in the PNW.

  • Complete vapor barrier Install a vapor barrier during the construction of your new adventure van. The overall idea is to install a barrier that prevents moisture from entering the vehicle and to prevent interstitial condensation from occuring. Using an impervious vapor barrier on the warm side of your insulation should help combat that issue.


  • Proper ventilation Allow the condensation to escape as best as you can (without letting that midnight rain into the van). I simply crack two of my windows open about an inch. Most of our clients opt for a ventilation fan to be installed in the ceiling. Others have found it easier to cut a discrete hole into the floor of the van, covered with a screen. The idea is to let the air out.


  • A diesel heater Some van dwellers run the car’s heater right before sleep. Others install a separate heater such as the Snugger Heater or other diesel heater options (you can read more about it in our diesel heater blog post). Others install a small wood stove. Cranking the heat up does help, but remember to couple it with proper ventilation. This makes sense because you will reach dew point at some point; the increase in temperature simply delays it.


  • Airflow (a ventilation fan) A vent fan can help introduce and maintain airflow in the van, especially if there is more than one person living in the space. Many fans require very low power to run and can do wonders ushering air out. The change in temperature inside the van provides a slight differential pressure gradient, allowing for there to be a moderate air flow in this situation. Therefore, a ventilation fan definitely helps make this process more effective.


  • Limiting exposed metal inside the van Metal is an excellent heat conductor but unfortunately does not absorb anything. Once at dew point in your van, water droplets will inevitably start forming on the surface of the metal, collecting into streaks.Consider the analog hygrometer, which is constructed from a smooth mirror-like metal that quickly collects condensation. Your van is, in essence, an expressive hygrometer.Therefore, it would be best to cover all metal surfaces with insulation, a vapor barrier, cloth, treated wood…etc. This action reduces the surface area for condensation to collect, and it allows you to more effectively warm the interior air.

  • Hygrometer ** (optional but it’s pretty neat to have) Installing a hygrometer not only impresses your passengers, but also provides you with information to empower you to continually improve your van’s interior.

  • ANHYDROUS CALCIUM CHLORIDE with Activated charcoal ** (optional and up for debate) This one is still up for debate and has had some mixed reviews. Products such as DampRid consists of anhydrous calcium chloride that absorbs moisture in the air. This specific product is designed to absorb moisture from an area of 300 square feet. I am really not sure why they live in a two-dimensional world as cubic feet would really help us in this situation. Although we wouldn’t recommend relying solely on this product for moisture absorption, it may be a crucial addition to the drawer full of wet socks.

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Definitely not getting dry any time soon. Here is my van, in pretty okay winter conditions.

Other extraneous tips:

Personally, I like to find a coffee shop or library to hang out in right before crawling into my van. That gives my clothes an opportunity to dry off while I get to read a book. Out in the woods, there are no coffee shops so the dry spots are limited. Even if it is raining, I begrudgingly shake everything out and lay them out on the dash near the cracked front windows. I do my best to avoid leaving wet clothes in a crumpled mess on the floor. Rituals are important in van life. At Freedom Vans, we take insulation and humidity regulation very seriously. We hope that this information can help you make the right decisions for your van and budget situation. Let us know how we can help you tackle the condensation issues that have come up, or how we can help you prevent it from happening.