When humidity is a problem

Often it occurs that in old buildings (but also in recent ones) there are spots, moulds or water condensate on walls and floors.
These are the superficial symptoms of a deeper problem:
the excess of humidity present inside structures or in the environment.
Solving this incoveniency is not always easy.
Treating surfaces with the numerous products available on the market is an often useless if not even counterproductive operation.
We must act on causes and not effects.
First we must locate the sources of humidity, to be able to act afterwards by eliminating them or limiting their action.

Humidty can come:

From outside:

• from the subsoil for capillarity

• from cyclical floods

• from the external atmosphere (falling rain)

• from the external or internal atmosphere (condensation)

From inside:

• water contained in building materials

• from internal damages (water disposal)

• from condensation of flush installation conduits

• from materials with different thermal conductivity and porosity which generate condensation phenomena.

Although it is possible to locate where water comes from by examining the exterior aspect of the spots, it must be said that this method is not very scientific and can lead to wrong diagnoses and to actions which do not solve the problem.
Only with an instrumental measure it is possible to get objective data about the intensity and the localization of water, on the surface or in the depths, which are not discernible to the eye.
Anyway in case you don't think an instrumental analysis is necessary you can follow the evaluations below.

• Persistent spots on the floor (ascnding humidity from subsoil).

• Persistent spots on the walls from the floor upwards (ascending humidity from subsoil).

• Strong erosion of the wallpaint in the central part or higher parts of the walls (ascending humidity in presence of ventilation).

• General and light haze, uniformly distributed (humidity from condensation).

• Isolated spots, variable in tone from day to day (alternated humidity from isolated materials, humidity from condensation).

• Light erosion of the wallpaint in the lower part, just above the floor (humidity from condensation, more rarely light ascending humidity).

• Efflorescences of the so-called "saltpeter", extended in a line or spot (humidity from rain penetration, but mostly from ascending humidity).

• Efflorescences of saltpeter on isolated bricks (it's not a sufficient sign for a diagnosis of humidity).

• Moulds (from any type of humidity, also minimal, but mostly from three causes: air stagnation, lack of sunlight, presence of organic compounds).

• Domestic fungus (from any type of humidity as long as ventilation is absent and there is cellulose).

In case the presence of humidity from upwelling is diagnosed you must verify if the water which goes up the walls for capillarity comes from inexhaustible sources (ie. water tables), or from stagnation of rain water or from water pipes leakages.
The degradation left by these sources is generally big, evenly distributed, with little variations in time.
Since it is not possible to drain the source you must bar horizontally the upwelling ways along the walls.
When the water comes from dispersed waters like stagnation due to bad disposal of rain or domestic waters, the damage is less spread and localized, with variations in time.
In this case it is convenient to localize the loss and act on it.

The himidity from condensation is more difficult to analyse.
Generally it spreads on the cold walls of the environment.

Condensation is influenced :

• by humidity in the air,

• by temperature and ventilation of rooms

• by the type of materials forming the structure,

• by superficial finishings.

The phenomenon can be distinguished into winter and summer condensation.
The internal temperature in winter is much higher than external temperature, this causes the dew point (point at which vapour condensates) to move towards the internal surface.
In this way humid hazes can form if the internal finishing materials are waterproof, or spots can form if finishign materials are absorbing.
Summer condensation occurs instead on walls with great thermal intertia, on which summer air (with a high absolute quantity of humidity) condensates.
The phenomenon manifests itself similarly to what happens when in summer we put a glass with cold water on a table and the humidity in the air condensates on the glass, wetting it.