How To Avoid Condensation In Tent

Yes, why a hiking tent it condense? Is it a forced passage? And what solutions then do not get soaked? Here are some explanations of some tricks to reduce condensation in your tent.


Before beginning on the tricks, we must understand why and how condensation is formed in a tent. And that’s where our physics-chemistry classes will serve us! 🙂


Condensation under the tent, how it forms?

Photo Credit: Gabriel Flores Romero.

Condensation is a natural phenomenon. It is the transition from a gaseous state to a condensed state (solid or liquid). In our case, this is water vapor (gaseous state) transformed into water droplets (liquid state).

In the wilderness, in the mountains, or by the sea, the condensation of water vapor is an important stage in the water cycle, at the origin of dew, clouds, and rain, the snow, the frost or certain forms of ice.

This change of state can be experienced in a shower where, in contact with the cold mirror, the water vapor in the air condenses into droplets.

In order for condensation to occur, a temperature difference between two surfaces is required: one is cold and the other is warmer. Tent condensation explained.


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The importance of the dew point when sleeping under the tent

We continue to learn a little with the explanations from our college courses! 🙂

The dew point (or dew point temperature) is the lowest temperature at which a mass of air can be subjected, at given pressure and humidity, without formation of liquid water by saturation.

To make it simple, above this temperature, there is a degree of humidity (or degree of humidity) of the air which is considered normal (of the order of 70 to 80% in France for outdoor ambient air plain). Below this temperature, the humidity increases to 100%.

Let’s take an example with a  moisture content of 15 grams of water per 1 cubic meter of air:

  • at 25 ° C., a level of 65% of moisture in the air
  • at 20 ° C., a level of 87% of moisture in the air
  • at 17-18 ° C, the humidity level in the air rises to 100%: it is the famous “dew point” or “dew temperature”.

When the dew point is reached, water vapor is deposited on everything it can find: soil, grass, trees, tents, etc.

Photo credit: Dude Pascalou.


What can cause moisture?

It will have been understood with the definitions given above: for there to be condensation, there must be moisture. In other words, if there is moisture, then there will necessarily be some condensation somewhere at some point!

In our alpine activities, what generates moisture? Lots of things in fact! In a mess :

  • the skin of the body: the human body is a fantastic heat generator (body temperature = 37.2 ° C). Made up of about 65% water, the human body naturally creates moisture, which is called sweating.
  • the air expired from the lungs: the same principle, the air we exhale is about 35 ° C, and charged with moisture. Just observe the water vapor created when exhaling in cold weather.
  • a rainy weather:  the clouds, and therefore the rain, are the first signs of a (very) significant difference in temperature. So if the air and the ground are loaded with moisture , and we heat the inside of the tent with our bodies …
  • the soil:  a soil, even of dry appearance, breathes, moreover if it is natural (soil, grass, sand, etc.). We find the same factors as our human body: a temperature difference between the inside and the outside, and a moisture content .
  • The proximity of a lake or a river:  a lake, a river, or a pond, will naturally be large generators of relative humidity .
  • a basin: a deep ground will favor the conservation of a cold and humid zone when the temperature decreases during the night.
  • The absence of aeration:  a place, a room that is not aired will naturally become damp. It is seen in closed rooms, with the appearance of molds in the corners for example (thermal bridges).
  • Heat water in his tent with his stove …
  • Etc.


How to avoid/stop condensation in a tent?

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So now that we have seen how condensation was formed, why it was formed, and what were the main generators of moisture, we will naturally be able to find tips and tricks to avoid that its canvas (or its tarp, because even a tarp can condense …) becomes a wet tissue.

As a preventive (for the location of the tent):

  • avoid putting your tent near a lake or river
  • prefer a location a little on the heights and sufficiently ventilated(one can reduce the force of the wind with stone walls for example)
  • avoid places that form a basin because the cold and the humidity are concentrated there
  • If possible, sleep in the undergrowth: trees (and forests in general) create a balanced ecosystem to maintain a constant moisture content and temperatures
  • If possible, choose a place quickly hit by the rays of the sun in the morning: this will dry the tent quickly before storing it in the backpack.


These are some tips for how to reduce condensation in a tent.

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As a preventive measure (for equipment):

  • Preferably choose a double-wall tent (outer wall, inner wall): this will promote gas exchange between the exterior and interior.
  • have a plasticised survival blanket under the tent: even if the floor mats of the tents are supposed to be impermeable, this will prevent soil moisture from flowing back directly into the tent
  • when installing the tent, make sure that the double roof does not touch the wall of the room: tent tight.
  • avoid the formation of folds on the tent canvas: they concentrate the condensation and allow the formation of drops of water.
  • open the aeration of the tent even when it rains.
  • leave a good space between the floor and the bottom of the double roof so that a current of air can be created from the bottom to the top of the tent
  • if possible, leave the top of the tent door open so that it is well ventilated, especially at night, when the temperature drops.
  • avoid to heat water in its tent: the moisture released is consistent, even with a lid, not counting the possible presence of carbon monoxide (CO) …


In curative (under a tent):

Once the condensation is installed, unfortunately, there are not many solutions! The only really valid is to gently wipe the wet surfaces with a microfibre towel: lightweight, compact, and formidable efficiency. Delicately, it is the master word, otherwise, we drop all the droplets on our dry business! 🙂

Photo credit: Hugo Clément.

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