In the past I struggled with finding a shelter that was condensation free, because I hated rubbing my shoulders against the water coated walls of my shelter in the morning. Or in a worse scenario, being awoken in the middle of the night by water droplets raining down on me from sort of micro weather inside my shelter or tent. Shelter design does play a role in the equation, but the other factors at play seem to rarely get mentioned, so I hope that I can shed some light on things to think about when you’re setting up a camp.
First though, I want to talk a little bit about the basic premise of what’s going on. Simply put, condensation is water from below the canopy of your shelter collecting on the non breathable layer of fabric as the air temperature cools and is unable to carry as much water vapor. It’s the same thing that occurs inside of rain gear from our bodies while it is in use. Breathable rain gear seeks to address the issue by allowing water vapor to escape, but while it helps, the rate at which it escapes is usually too slow to keep up with the amount of moisture being put off by our bodies especially under high exertion.
Typically shelters are not made with breathable fabrics, with the exception of bivy sacks. Bivy sacks usually suffer from the same problem as rain gear where the fabric is unable to breathe enough to allow the water vapor from either your breath, body or the combination of the two, to escape. Tents and tarps however, are not made from breathable fabrics, so the way which they deal with water buildup is through ventilation.
Tarps will naturally have the least condensation, as airflow is pretty much unimpeded in most situations and can keep any buildup to a minimum. Having enough condensation on the belly of a tarp to cause dripping is rare except in very wet circumstances.
Tents ventilate to a much lesser degree typically, but get around the problem with what I consider a band aid in some ways. By using a double layer construction the keep a layer of fabric between you and the outer non breathable fabric so that you don’t contact the wet surface of the outer wall. This makes life more comfortable, but it doesn’t keep the outer wall of the tent any drier, but rather just covers it up. The part or a tent that can help with condensation over a tarp or a single wall shelter is the waterproof floor. The floor will keep the water on the ground from entering the shelter.
Single walled floorless shelters don’t breathe any less than a double walled shelter with equal ventilation, but they cut weight by removing the inner fabric, and can have more condensation at times due to the ground and any moisture it holds not being covered up by a floor. The introduction of a wood burning stove can dry condensation inside a shelter as well, but remember that much of the water will be absorbed into the warmer air, and will reform as condensation when the fire is out and the air temperature cools again.
Tents intended for warmer weather and 3 season use often have much more ventilation in the form of large mesh panels which allow air to flow more freely. When possible, setting up a shelter with as much ventilation as you can will minimize condensation.
The following are a couple ways that I have learned to pick camp locations that have helped me minimize condensation issues in all types of shelters.
Find Dry Ground
Simple but not always easy would sum this one up for me. If the weather has been wet, it sometimes becomes a case of picking the spot that is the least bad. If you look around though you’ll find dry spots, especially near or under trees in heavy forest canopy, or in open rocky areas with soil that drains water very rapidly. These areas hold much less water that will come from the ground under your shelter during the course of the night.
Plants hold a lot water, and some of that water will end up on the walls of your shelter. I look for areas clear of all grasses and forbes. Once again, sometimes this is a matter of finding the best site available if an ideal one isn’t present.
Keep Wet Gear Outside
This isn’t always the most practical in bad weather, but if you can find a dry spot to stash gear, or the weather has broke and your gear is still wet, keeping it outside will minimize the amount of water present inside the shelter.
All 3 of these concepts will help to minimize the condensation that will form at night, but that doesn’t mean they are a cure all. The trick to a dry shelter is much like that of staying dry inside rain gear. There must be equal or more ventilation and airflow to overcome the amount of moisture present. Water vapor produced by your body and by breathing will always be present in the equation. However minimizing all the other introduced water when possible will keep things drier.
It also doesn’t always take a lot to make a drastic difference. In one of my favorite hunting spots there are two old camp locations about 50 yards apart in a valley bottom. The first one will have so much condensation that it will rain under a shelter even in very dry weather. The second on is often bone dry inside a shelter even in prolonged rain. This was one of the first clear illustrations that taught me how much a little bit of difference in site selection can make.
One last extra tip I have is to keep something to wipe the inner walls of your shelter off with in the morning. Doing so will help prevent mildew, will get your shelter to air dry faster during the day, and will avoid packing excess water weight in your pack when you load it back up. A small pack towel, or half of a sponge work well for this and they can be wrung almost completely dry and they weigh very little.