Answer: thanks to a vapor barrier or a VMC.
The inhabitants of a dwelling produce a large quantity of water vapor. It is essential to evacuate this vapor outside for reasons of insulation. There are two options: a vapor barrier with added VMC and the use of porous materials that offer the possibility of removing water vapor without bringing in air. If you do not want to install a vapor barrier, you must allow the evacuation of water vapor. For this, you can for example install vapor barrier films or wood fiber panels with tongue-and-groove assembly, provided only to observe the rule of increasing permeability from the interior of your house to the 'outside. Installing a window seal Our practical DIY videos