Answer: a drain installed in the foundations and connected to the public network.
To treat humidity problems, an internal drainage of the house can be put in place, if it is not possible outside. The operation then consists in digging a trench 40 to 60 cm deep, then installing a drain there. This is then connected to the rainwater network. It is also sometimes necessary to install a lifting pump if the floor of the house is lower than that of the public network. This foundation drainage solution from the basement is particularly effective on old houses with porous walls. It only concerns cases where moisture comes from the ground, by capillary risings or infiltrations. Once installed (if you are not sure of yourself, call a professional), the drain must be regularly checked: clogged, it would no longer be of any use. You too, send us your DIY question.