How to treat damp interior walls:tips, solutions, prices

Damp problems are not uncommon in homes and are a real pain! Sometimes difficult to identify, it is often even more complex to remedy them definitively. However, there are solutions! Here are some tips to help.

First step:identify traces of humidity at home

If nearly one in five households is affected by a humidity problem in France, identifying the signs is not always easy. This indeed manifests itself in several ways, sometimes in one way, sometimes through several signs.

Anyway, if you see at least one of the following symptoms, your home is affected by a humidity problem:

• Visible and touchable moisture on the walls;
• Damp stains and halos on your walls, ceilings and/or floors;
• Mould on the lower parts of the walls, corners, door surrounds and window edges;
• Renders, wallpapers, wall coverings, murals and/or paneling peeling, blistering or warping;
• Saltpetre appears on the surface in the form of whitish foam;
• A musty smell and/or mold is felt in the rooms.

Second step:research (and find!) the causes of humidity

Before you jump into any hide-and-seek, look for the cause of the dampness. Treating the surface will be useless if you do not know where it comes from. Imagine that you have to treat an illness; you need to find the cause to find the right remedy and not just swallow drugs unnecessarily. It is essential to find the source of the problem to solve it, you will avoid a significant waste of time and money by proceeding logically!

The causes of humidity can be multiple:

• Defective or insufficient ventilation:if the humidity cannot be naturally evacuated by the ventilation, it remains in the rooms and settles on the walls. This leads to condensation, damp marks and mould.
• External infiltration:if your door and window surrounds are cracked, if your tiles are loose, if the seals or coatings on the facades are ineffective or obsolete, water infiltrates and lodges in your walls up to to stand out in your interior.
• Capillary rise:ground water rises to the surface if your foundations are poorly designed.
• Water damage can also cause moisture problems.

If in doubt, call a professional. He will be able to identify the cause of the humidity and suggest solutions or give you advice on how to remedy it.

Third step:deal with the humidity problem

We have already said it, but it is essential to remember that before embellishing your walls to hide traces of humidity, it is imperative to treat the problem at its source.

Depending on the origin of the humidity, several works can be carried out:

• If it is poor ventilation , it is recommended to improve it. Install a VMC to better renew the air and effectively fight against condensation, especially in humid rooms such as the kitchen and the bathroom. Have the system checked, clean it and replace it if necessary so that it is properly sized for your home. In addition, do not hesitate to ventilate your home for at least 5 minutes every day.
• In case of infiltration , identify the source and remedy it without delay. Insulate your walls from the outside, fill the cracks and make the necessary repairs so that water can no longer infiltrate. If necessary, change poorly insulated doors and windows; it represents a certain investment, but you will gain over time.

• To fight against capillary rise , inject resin and perform sufficient drainage to completely sanitize your foundations before protecting them with a waterproof membrane.
• If the origin of the humidity is a leak , have it repaired without delay. Often, when a pipe break is the cause, traces of moisture appear when the wall is already waterlogged. Don't wait any longer to act!

Fourth step:do your decoration work

Has the origin of the damp been properly identified and is it properly repaired? Perfect ! You now have to… wait again! Wait until your walls, ceilings and/or floors are completely dry before tackling your decoration work. This step is often very painful, but it is essential.

Indeed, although the problem has been repaired at its source, the moisture is still present in the surfaces. The walls, floors and ceilings are still full of water stored for several days, weeks, months or even years! If you already cover your surfaces, the same problems will reoccur (peeling wallpaper, blistered paint, warped paneling, etc.). Likewise, if you immediately apply an insulating and anti-humidity coating, the stored water will seek another path and will spread to the heart of your surfaces to come out further.

So before decorating your home, wait several days, or even several weeks depending on the damage, so that the walls, floors or ceilings are completely dry. You can then start your work:

• Brush and thoroughly clean the affected walls, floors and ceilings, paying particular attention to the areas most stained by humidity. This step will allow you to start fresh, on a healthy wall free of mold and bacteria due to stagnant water.
• For some surfaces, such as plaster or wood, it may make more sense to completely replace a wall if the water has penetrated deeply. The latter tends to cause certain materials to swell, which creates irregularities on the surface. In the case of tiles, it is also advisable to replace the affected elements.
• You can, if you wish, apply a water-repellent surface treatment. This layer will properly insulate your walls, floors and/or ceilings from remaining moisture hazards and will prolong the shine of your surface decoration.
• Lay down your wall, floor or ceiling covering:wallpaper, carpet, paneling, parquet, plaster, paint, tiles, etc. You are now free to apply whatever you want!

If the source of the humidity has been identified and repaired, and if you have given your walls time to dry properly, your coverings should no longer suffer from the hazards associated with this problem.

What bill, what price to treat the humidity of a house?

This work has a cost, which obviously varies according to the service. For the installation of a CMV, count between 150 and 1500 euros depending on the model chosen and any work to be carried out. To treat a problem of capillary rise, the bill will be between 30 and 60 euros per linear meter.

To dry a damp wall, you can buy your own drying plant for a budget of 500 to 2000 euros, or carry out sanitation work by injection for 50 euros for 5 liters. A drainage will cost you up to 3000 euros depending on the surface to be treated. If you hire a professional, the price can vary from 2000 to 6000 euros, supplies included.

Finally, add to that the cost of water-repellent treatments, around 10 euros per litre, and embellishment and decoration work.