The reality is that you cannot prevent tent condensation, this is a normal physical process. It comes due to the cooling of the hot air inside the tent on the walls of the tent. The vapor from the air loses its energy in contact with the cold wall and it transforms into the liquid.
There is always moisture in the air and it is increased with what a person breath out. In the case of a drop of temperature outside of a tent, you will have moisture on the fabric inside the tent. So you cannot avoid condensation but you may try to reduce it, and this text is about some basic facts related to this.
So how to prevent tent condensation? Here are a few things to bear in mind:
- Find a double layer tent.
- Find a tent with vents (on the fly or elsewhere), the more vents the better.
- Avoid cooking in the tent.
- Keep the stuff in the tent dry.
Two layer tents and single layer tents
The material of the inner layer is normally water repellent and breathable. Its role is to let vapor pass through, and at the same time, it is supposed to prevent water condensed on the fly falling directly on you. A general feeling in a double layer tents is that it is more comfortable than the single layer tent.
Then why making single layer tents? The reason is the weight of course. If you are on long tours where grams count, a single layer makes the difference.
The outer layer (the fly) is exposed to elements and it may lose its waterproof properties and it may be damaged, so you can replace it and have a ‘new’ tent again.
Here is a nice video by MSR with some details about condensation in the tent. I am a physicist by profession and can say they have described the phenomenon quite accurately. Please have a look:
Ventilation and air circulation is of particular importance for reducing and preventing tent condensation. So this alone does not solve the problem but it can reduce it very effectively. Good tents will have vent(s) on the fly. You may see some in the case of Marmot Limelight 4P tent or Marmot Tungsten 3P tent (in the picture on the right) which has 2 vents on the fly.
In the case of Sierra Designs Lightning 2 FL you have a vent in the foot area and this makes a lot of air circulation. On the other hand in the case of NEMO Galaxi 2P a sort of vent is available at the zippered opening, see more in the text here.
Avoiding cooking in the tent, keep the tent dry
I guess the statement about cooking does not require a lot of explanation, this is self-evident.
If you have wet clothes, try to dry them outside of the tent. In my texts about sleeping bags, see for example this text about Sierra Designs Backcountry Bed, I have been writing about facts that down insulation loses its features when it becomes wet. Wet stuff in the tent will increase chances for condensation.
In addition to the tips given above, here are a few more:
- Pitch the tent at some distance from water.
- If the tent has vents, pitch it in such a way to be lined with the natural air flow in the surrounding area.
- If you are using a footprint (tarp) with a tent, make sure it is completely under the tent. Otherwise, it will collect the rain and funnel it under the tent. You want the surface under the tent to be dry.
- If possible, pitch the tent on a slightly sloped terrain so that eventual rainwater does not collect under the tent.
- Use sleeping pads with a water-repellent material, otherwise, they will behave like a sponge and become wet, and with this everything else will become wet.
Thank you for reading this text about ways to prevent tent condensation. Have a look into the texts about tents mentioned in the text above. The complete list of them you will see in my Equipment Reviews page within this site.
If you find this text useful, please share it with others through social media. I shall be happy to have some comments from you. Note that there is a comment box below.