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Substrate moisture

Substrate moisture
Measuring moisture in a screed or a wall before painting or installing any floor coating allows to guarantee the quality of work.

Moisture, a major source of disasters

Peeled walls? Unstuck textile floors? Excess moisture in a structure causes a lot of damage.
Concerning building finishings, most of the disasters are due to excessive moisture in the structure (overlaying, panels, fabric) or in the support base (concrete, wall, floor).

Causes of moisture

Moisture comes mainly from:
- Residual water after preparing the material (plaster, concrete, cement, etc…). This is mainly due to very tight implementation times, which don’t leave adequate time for proper drying.
- Migration or rising damp. This usually happens in old buildings, where water from the underlying soil seeps into the walls.
- Leaks in the plumbing system or drainage.
- Seal defects in the walls or roofing.
- Flooding.

Measuring floor moisture

Installation of floor coatings (tiles, carpets, floor boards, resin or plastic flooring) or wall coatings (paint, wallpaper or fabric) is to be preceded by in depth relative humidity test.
Ambient humidity and temperature of the floor slab are to be such that there is no condensation in the structure: the temperature of the floor slab is to be higher than the dew point.

Standards and commitment

Monitoring a structure means being able to identify its quality, especially its moisture content. It allows the person installing the floorboards, carpet or tiles or applying the resin or paint to commit herself.
Some standards standardise and formalise floor expertise before the installation of a floor covering or coating.
Follow some examples.
- The NF DTU 53.2 –PVC resilient floor coverings- and NF DTU 54.1 –resin floor coverings- states the dryness of any structure must not exceed the Equilibrium Relative Humidity (ERH) of 85% for PVC floor coverings (NF DTU 53.2) and 80% for resin floor coatings (NF DTU 54.1).
- The ASTM F 2170-02 is the US Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probe.
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Recommanded products

Humitest for building

This moisture meter for building materials allows to measure water content of screed, floor screed, drywall, heavy concrete brick, brick…
Adjustable thanks to it optional sensors:
- Infrared surface temperature probe
- Thermo-humidity probe
- CO2 probe

Humitest MMS2

Four-in-one system: two-pin-contact moisture meter, in depth radiofrequency moisture detector, infrared thermometer, fast responding thermo-hygrometer.
- intuitive user interface with color screen,
- data logging,
- firmware upgradable,
- psychometric calculations,
- non-contact IR temperature probe with laser pointer.


"Substrates moisture content, main cause of pathologies"

Equilibrium humidity content

Also known as the hygroscopic equilibrium, this term is used to define the water equilibrium of a material in relation to external conditions.

Thermal efficiency and dryness

The thermal performance of a wall depends on its dryness. Before installing an insulation system, wall dampness is to be removed.