Water infiltration : causes consequences and treatment

In the long run, water infiltration can end up causing enormous damage to a building. Rainwater can penetrate the walls, the roof, the buried parts… and endanger the building. What are the causes and consequences of these infiltrations, both for the house and for your health? We help you take stock, to better consider the most effective solutions.

How do you recognize water infiltration?

No need to be Sherlock Holmes to spot the progression of water infiltration. With a little observation, you will surely recognize the most visible signs of humidity. On the walls, stains of damp appear, recognizable by their aspect of a more or less dark yellow halo, tending towards brown. When you run your hand over the wall, it feels damp to the touch. Sometimes you can even see droplets oozing out. Paint is peeling, wallpaper is peeling, woodwork is swelling and rotting. A white deposit appears under the paint or the wallpaper… With your eyes closed, you can smell the humidity in the air and its lingering musty smell.

In short, these signs of humidity do not deceive. When one or more water infiltrations have reached the house, it’s time to act. Have a professional confirm your diagnosis with a thermohygrometer (try Scrabble, that one). He will tell you in particular the humidity level, the weight of water present in your walls… and will identify any cracks in question.

Water infiltration: what are the causes?

The causes are multiple, that’s the problem! Rain can find several entry points to make its way into a roof or a wall, especially if the building has some defects. Water can also rise from the ground, infiltrating the walls by capillarity.


A crack is a royal way of infiltration, whether in a wall or in a ceiling. It can be superficial (shallow and on the surface) or through (in the thickness of the wall). Some cracks are formed by the impact of ground movements on the construction; others come from an unsuitable coating…

A porous material

Some building materials are naturally porous, their structure being formed of small holes: limestone, brick, cellular concrete, earth, tufa… When it comes to materials with an open porous structure (the small holes are connected between them through small channels), elements such as air or water can infiltrate them.

A sealing problem

At the time of construction or installation of a structure, a poorly made junction may cause a leak. This can occur from the foundations, during the construction of a facade or the roof, the installation of a terrace, a balcony or the door frames… Also involved are worn joints (for example those of the tub).

A construction defect

In some eras, houses were built on foundations without waterproofing. Ideal for letting moisture from the ground rise in the walls… In this case, the moisture rises by capillarity, traveling through the interior walls.

Water damage

An accident can always happen. A burst pipe, a leak, a flooded river… Water infiltration can occur unexpectedly in your home. Lack of maintenance of the gutters is also a great classic; clogged gutters are the source of many infiltrations.

A level difference

If your house is lower than the ground, the ground level inside being lower than the outside, the risk of infiltration is increased.

The natural elements

Bad weather can aggravate or even cause water infiltration. Rain gradually soaks too porous materials. Hail can clog drains and install lasting humidity. The snow piles up quickly and melts slowly, which makes it a perfect cocktail for invisible infiltrations (eg under the roof tiles). The wind pushes the rain towards the walls, causing infiltration through cracks…

Double consequences: on construction and health!

Do not neglect the effects of seepage. Not only do they weaken the construction, but they can also pose a health hazard to the most fragile people.

The house is leaking

It is better to react at the first signs because an infiltration never stops its progression. The worst that can happen is that the walls and ceilings become waterlogged. Thus weakened, the entire structure is threatened. In extreme cases, we can witness the collapse of a ceiling or part of the construction. Even if it is rare that it comes to this, the problems can quickly accumulate:

  • The paint blisters, the coatings and the wallpapers peel off.
  • The wood rots.
  • The stone crumbles.
  • Metals are attacked by corrosion.
  • The saltpeter appears, which is called the leprosy of the walls.
  • Mold develops (with its characteristic smell), and sometimes dry rot, a fungus that damages the structure…
  • If the insulation is reached, it no longer plays its role.
  • If the frame is touched, it becomes fragile.
  • Inside a wall, water can encounter the electrical installation: beware, danger!

If we don’t react until it’s time, the house ends up rotting from the inside…

Many health problems

We are not made to live in an environment that is too humid, not to mention mould… Health problems primarily affect fragile, sick or elderly people, and children.

  • The allergies Are growing. They manifest themselves in various ways: irritation of the throat, asthma, allergic conjunctivitis… In question: molds and dust mites. Humidity promotes the growth of fungi, the particles of which are particularly allergenic. Similarly, dust mites appreciate ambient humidity, growing in bedding, textiles, carpets, wherever they find favorable conditions. With an ambient temperature above 20° C and a humidity rate above 50%, mites are the kings of oil. In a room, the ideal way to prevent their development is to maintain a temperature between 16 and 18° C, with no more than 50% humidity.
  • joint problems are accentuated. Rheumatism, arthritis, osteoarthritis… People with sensitive joints see their pain worsen.
  • breathing problems may appear: irritation, cough, asthma.
  • In some people, a chronic fatigue settles down.
  • skin reactions can be caused by mold, due to the development of staphylococci. Life in a damp house becomes hell for some people.

Fight against water infiltration: what solutions?

To precisely identify the origin of the infiltration, start by asking a professional. This expert will establish a diagnostic who will help you assess the seriousness of the situation and suggest suitable treatments. The solutions are different depending on whether it is an infiltration linked to the roof, to a wall covering or to a rise through the ground…

Let it dry

While waiting for the professional’s diagnosis, you can dry the floors and walls of infiltrated water. For this, sponge and air widely – if the season lends itself to it. And if that’s not enough, use a dehumidifier.

Visible causes: repair, seal, restore!

Have you spotted the origin of the infiltration? Repair the visible causes as soon as possible to limit the damage.

  • Replace the tiles, change the plasters, seal the cracks, unclog the gutters…
  • Repair damaged walls, if necessary by calling in a mason.
  • If the corrosion reaches steel elements, they must be treated. The damaged concrete areas are to be reconstituted at the
  • To fill the cracks, you can use putty. This product is applied on a dry surface. It will protect the wall against the outdoor elements, water and dust, ensuring the wall is watertight.
  • For problems with the roof, call a roofer.

Infiltration by the ground: make a drainage of the walls

If the infiltration is linked to a leak in the buried walls, the drainage technique is essential. No point trying to solve the problem without draining all the water first. The intervention is quite expensive: between 100 and 300 euros per square meter.

In a room: install a waterproof membrane

If the infiltration from the ground has developed on an interior wall, the solution sometimes consists in installing a waterproof membrane in the walls, which ensures their tightness.

Porous exterior walls? Water repellent!

What is water repellency (besides a great word for Scrabble)? This involves applying an invisible layer of protection to the wall using a waterproofing product. The product fills the porosity of the material and protects it from water and frost. As a bonus, the facade stays clean longer! The water-repellent treatment is applied to a previously cleaned and repaired wall. Count 8 to 15 euros per square meter.

Or apply an anti-humidity paint

This simple technique consists of painting the exterior wall with a paint designed to protect it from humidity. Easy to apply, provided you have cleaned the wall beforehand, this type of paint is washable. It can be used preventively. Budget: 20 to 40 euros per square meter.

Install new siding

This complete solution makes it possible to solve major problems of infiltration on a facade while giving it a new appearance. In addition, it is an opportunity to reinforce the insulation of the exterior walls. Installing an impermeable coating is a more expensive technique than the previous ones; expect 20 to 250 euros per square meter.

Inside: consider ventilation

Water infiltration can be associated with condensation, if the air does not circulate enough. Installing a ventilation system solves this kind of problem. If necessary, it will have to be considered for the whole house.

Replace damaged insulators

In the event of infiltration, the insulation can be damaged and no longer fulfill its role correctly. After removing them, replace them with new ones. If the damage is significant and all the insulation needs to be redone, take the opportunity to choose a more environmentally friendly insulation.

Facade treatments should preferably be done at the end of summer for rapid drying. Otherwise, you can always opt for a heat gun.

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