Wet cellar : causes solutions treatments and cost

A damp cellar is very unpleasant. The room has a musty smell, it can become covered with mold and the belongings stored there gradually deteriorate.

But the problem does not stop there! If you don’t act quickly, the humidity in your basement can seep into your entire house and weaken its foundations. However, it is imperative not to undertake just anything; we must act quickly, but well! Here are the tips from our experts to help you solve your damp cellar problem and find a healthy room.

What are the possible causes of a damp basement?

A damp basement is obviously a sign of a humidity problem. There are several possible reasons for this fact:

  • Exceptional water damage (flooding, rupture of a pipe, etc.);
  • Capillary rise that permeates and moistens the foundations of your home and infiltrates the floors and walls;
  • The presence of a high and nearby water table which tends to put pressure on the foundation walls until it infiltrates the cellar;
  • Water infiltration due to poor evacuation and poor drainage of the water contained in the soil of your land and which tends to impregnate the foundations and buried walls.

Having a damp cellar can lead to more or less serious consequences within this room, but also throughout your home. Indeed, water or mud can form on the ground and permeate all of your surfaces. The various finishing materials such as coatings, paint, floor coverings or even paneling have deteriorated. The materials and objects stored in your cellar soak up moisture and are attacked by mold and fungi, which contributes to their deterioration little by little. Your floors, walls and ceilings can also become covered with mold and fungus, visible on the surface or through the brownish stains they form deep down. Damp upwellings can infiltrate along the walls over time and invade your entire house, which greatly weakens it; moreover, in the event of adjoining, it can spread to your direct neighbours.

Be aware that humidity also has serious consequences for your health. If the cellar is generally an uninhabited room, it nevertheless constitutes a storage place where you are likely to go more or less frequently. In addition, if humidity rises to the core of your home, it can trigger allergies and respiratory illnesses.

What solutions and treatments can you consider?

Several treatments and solutions are possible to solve a damp cellar problem; sometimes, the combination of several of them is even necessary to achieve a convincing result. In any case, act as soon as possible so as not to let the humidity spread and to be able to solve the problem more easily.

Before you start, the first step is to call a professional who will carry out an accurate diagnosis. This device detects the source of the moisture. Do not decide to do it yourself, because it is often difficult to identify the source of the problem without suitable measuring devices. Indeed, humidity can have several origins and take several forms. Only a professional will be able to identify the problem and advise you on the solution to it.

Better ventilation

Sometimes a simple upgrade to your basement ventilation system can be enough. Install a single-flow VMC to facilitate air circulation and naturally evacuate humidity.

The drying out of the walls

Drying the walls is a solution used alone if the source is for example a flood, or more generally in addition to other techniques in order to perfect the elimination of humidity. Indeed, the drying of the walls is generally necessary even after the resolution of the source of the problem in order to proceed with the finishes.

Injection of resin into the walls

The injection of resin in the walls prevents water from circulating in your walls through the capillaries of the foundations.

To do this, holes are drilled in your walls at ground level and a water-repellent gel is injected into them. The latter forms a real barrier to solve, for example, the problems of capillary rise.

Floor drainage

Drainage improves the natural evacuation of water present in the soil. This solution is preferred when the land is poorly drained and rainwater tends to stagnate around the house or near the basement.

To do this, the professional puts a suitable waterproof bubble cover on the walls and floor of your cellar, then he puts a new floor and new walls on it. A drainage is then operated in order to absorb the humidity and to evacuate it towards pipes.

Installation of a waterproof membrane

The installation of a waterproof membrane all around your foundations makes it possible to retain the infiltrations of the water contained in the ground. This technique uses hydrostatic pressure to be effective.


This technique consists of forming a kind of perfectly sealed box within your cellar. However, it is not used by all professionals, because waterproofing tends to move moisture elsewhere without eliminating it, especially if the casing is applied from the inside. This then settles elsewhere and creates new sources of moisture.

On the other hand, in the case of an underground origin of the water source (groundwater, etc.), this solution may be of interest, provided that it is applied from the outside or coupled to a exterior protection and drying of the walls.

Very often, when water or traces of its presence (mold, brown marks) appear on the surface, it means that it has already infiltrated your home. Act very quickly, as it can be very difficult to eliminate it permanently once it has taken hold.

Also, avoid hiding the problem by changing wallpaper or applying a fresh coat of paint. You’ll just be hiding the dampness for a while and your jobs will be good to do again. Avoid wasting your time and money and act at the heart of the problem to overcome it definitively.

As a preventive measure, regularly check that your drains are not clogged. Overflowing in the event of heavy rain may aggravate the moisture problem and allow water to seep into your basement more easily. In addition, equip your cellar with a good ventilation system, either by opening windows that you can easily open without the risk of letting water in, or by a VMC studied to the dimensions of your room.

Treating a damp cellar: how much does it cost?

Let me tell you right away, this type of work is similar to heavy work and can be relatively expensive. Hence the importance of acting immediately, as soon as you notice the first appearance of humidity.

Each service has its own cost, more or less important. Nevertheless, it is advisable to adopt the right treatment, the one that will be recommended to you by a competent professional, and not the cheapest if it is not suitable. A humidity problem can have serious consequences on your home; it is better to act immediately with a consequent treatment, than to ruin yourself in repeated and useless repairs which will not be able to slow down the further deterioration of your house.

Call a professional to be sure of the result and to carry out a preliminary diagnosis. Identifying the source will allow you to fix the problem and effectively remove the moisture.

Get quotes from several specialists and opt for a competent professional at advantageous rates.

If the costs of the services are likely to vary greatly from one professional to another and from one region to another, here is an average indication of the prices practiced by intervention:

  • For a diagnosis, count between 300 euros and 800 euros.
  • For the detection of a deep leak, the average price is 300 euros to 400 euros.
  • For better ventilation, plan a budget of 1,500 euros to 6,000 euros.
  • To inject resin into your walls, count on average 100 euros to 150 euros per running meter.
  • For a clogging, the price varies between 4,000 euros and 10,000 euros.
  • For interior casing, count between 15 euros and 17 euros per m².
  • For casing from the outside, the average price is 60 euros per m².
  • For the drainage of the cellar, allow between 3,000 euros and 10,000 euros, depending on the surface to be covered.

You have understood it, do not wait any longer and act quickly!

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