Moisture in the basement can harm the building

Problems with moisture in the basement should be taken seriously

A problem with moisture is not necessarily visible. However, there will often be visible signs that point to problems with moisture. For example, loose plaster and/or wallpaper, peeling paint, stains on floors/walls/ceilings and musty smells.

If there are problems with moisture in the house, it can lead to various other unpleasantnesses. Among other things, mould, which can affect our health, as well as other types of harmful fungi. For example, house and timber fungus, which can damage the building’s structure. In addition, house dust mites, which many people are allergic to, thrive in humid environments.

Since, as mentioned, there can be different reasons for challenges with moisture in a building, there are also many different solution options. It is therefore largely about finding the solution that ensures the optimal result, at the right price.

Moisture in basements

There can be many different causes of moisture in basements. Often it is due to rising or seeping groundwater, but it can also be due to condensation and thermal bridges. Or a combination of these causes.

If the moisture is pushed up through the floor, the floor is probably older and therefore not built according to the standards used today. For example, a concrete floor that is laid directly on the ground underneath.

To get rid of the moisture problem, it will usually be necessary to make a completely new floor construction that meets current building requirements. If it is a floor in a living room, it will be advantageous to install heating in the new floor at the same time.

The moisture problem can also be remedied with a so-called floor membrane, which is placed on the existing concrete floor. However, this solution is only applicable if there is or will be a wooden floor or similar laid over the concrete floor.

If there are problems with or risk of problems with elevated levels of radon in the building, the floor membrane can advantageously be a version that also protects against radon.

If the problems are due to moisture condensation, ventilation or active ventilation, such as single-room ventilation with heat recovery, is usually the best and most effective solution to eliminate the problem.

When the basement walls get air (can "breathe"), it reduces the risk of the formation of, for example, mould quite considerably

Moisture in basement walls

If you have problems with moisture in basement walls, you should first ensure that the walls can “breathe”. Therefore, there should be no interior cladding on the basement walls, and no plastic paint or other diffusion-permeable surface treatment should be used that can “encapsulate” the moisture inside.

For the interior surface treatment of basement walls, you should always choose diffusion-permeable materials. This can be, for example, so-called renovation plaster (special mortar) or silicate paint. This ensures that the walls can “breathe” and thus get rid of any moisture.

When the basement walls get air (can “breathe”), they can better get rid of any moisture to the surroundings. At the same time, it reduces the risk of the formation of, for example, mould quite considerably.

Additional measures for moisture in basement walls may include:

Ventilation: There should be good ventilation in a basement. This can be ensured with fresh air valves in all basement rooms. For larger rooms, there should be more valves. In addition, there must be an exhaust duct or a moisture-controlled fan in the basement room where the risk of moisture is greatest.

Heating: If there is not already one or more heat sources in the basement, radiators should be installed so that basement rooms never get too cold in winter. Ideally, there should be 18-20 °C in all basement rooms.

Perimeter drain: Perimeter drains are installed along the outer part of the basement’s outer walls in gravel or stone below basement floor level. At the same time, the outer wall must be insulated on the outside, preferably with diffusion-open insulation, e.g. mineral wool, so that the walls can also release moisture this way.
Prevent rising damp: If moisture in the basement wall is causing moisture to be absorbed into the walls, a moisture barrier can be established. This can be in the form of drywall or metal sheeting between the foundation and the basement wall.

You can choose to have a professional investigation for moisture and mould carried out. Once you know the problem and its extent, you can find the best way or ways to tackle it

Basement moisture protection

If you have an older basement, moisture can be difficult to avoid. However, you can take various measures to get rid of or reduce moisture in your basement.

Before you start basement moisture protection, you should first make sure what the basement will be used for, so that the effort is commensurate with the yield. As long as moisture in the basement does not penetrate the beams in the floor separation or higher up in the house, the moisture is not directly harmful.

Ultimately, it is more a question of keeping the moisture under control. Therefore, you should first examine the basement for any problems with moisture and mould, and how large the extent may be, before you possibly initiate basement moisture protection.

You can therefore choose to have a professional investigation for moisture and mould carried out. Once you know the problem and its extent, you can find the best way or ways to tackle it.

Ventilation in the basement can be done in many ways

Ventilation in the basement

Fresh air vents are usually enough to ensure good ventilation of basement rooms. On the other hand, you also throw warm air straight out of the air vents – and thus increase heating costs.

Therefore, it is advantageous to consider mechanical ventilation with heat recovery instead of fresh air vents to ensure good ventilation of the basement. This achieves an effective replacement of the “boring” air with fresh air from outside, without “burning the house sparrows”.

With a so-called heat recovery system, whether it is a central system or single-room solutions, you can utilize the existing heat to heat the fresh air that is blown in. A so-called heat exchanger in the ventilation system itself ensures this.

Single-room ventilation with heat recovery can be preferable in many cases. It is simple and relatively inexpensive to establish, and it also ensures that the ventilation of the basement can be easily adapted for each individual room.