Knowledge Base

Dew Point

Why Dew Point Matters

One of the most overlooked factors when installing resin flooring is the relationship between the substrate temperature and the surrounding air conditions. Even when a concrete floor appears completely dry, invisible moisture can form on its surface if the temperature falls too close to the dew point.

The dew point is the temperature at which airborne water vapour condenses into liquid water. If the substrate temperature is at or below the dew point, or within the recommended safety margin, a microscopic layer of condensation can develop across the surface. Whilst often impossible to see with the naked eye, this moisture can significantly affect the performance and appearance of any resin flooring system.

For this reason, the substrate temperature should always be at least 3°C above the calculated dew point before application begins.

Why Is It Important?

Applying a resin floor over a surface affected by condensation can result in a range of installation problems, including:

Reduced adhesion to the substrate.
Gloss variation or loss of gloss.
Surface haze or whitening (blushing).
Pinholes, bubbles or craters.
Surface imperfections and cosmetic defects.
Reduced long-term durability of the flooring system.

Many of these problems may not become apparent until after the coating has cured, often requiring costly repairs or complete replacement of the affected area.

How Is Dew Point Measured?

Determining whether installation conditions are suitable requires three measurements:

Air temperature
Relative humidity (RH)
Substrate (surface) temperature

Modern digital environmental meters automatically calculate the dew point once the air temperature and relative humidity have been measured. A separate surface temperature probe or infrared thermometer is then used to measure the temperature of the concrete or existing floor.

Professional flooring contractors commonly use instruments from manufacturers such as Elcometer, TQC Sheen, Testo and Tramex, many of which display the substrate temperature, dew point and the temperature difference simultaneously. This allows installers to quickly confirm whether safe application conditions have been achieved.

Environmental Conditions Can Change Quickly

Dew point is not a fixed value. It changes continuously as environmental conditions change throughout the day.

For example:

Warm, humid mornings may produce condensation on cool concrete floors.
Evening temperature drops can rapidly reduce the safety margin.
Opening loading doors or increasing ventilation can alter both air temperature and humidity.
Newly constructed buildings or recently washed floors often contain elevated moisture levels.

Because of this, environmental conditions should be monitored before installation begins and periodically throughout the application process, particularly on large projects or where weather conditions are changing.

Dew Point and Aspartech Flooring Systems

Aspartech polyaspartic flooring systems offer significant advantages over many traditional resin technologies, including rapid curing, excellent chemical resistance and improved tolerance to challenging site conditions.

However, no resin flooring system should ever be applied onto a substrate affected by condensation.

Although polyaspartic chemistry is generally less susceptible to moisture-related surface defects than many conventional epoxy systems, the presence of condensation can still lead to reduced adhesion, uneven finishes and other coating defects. Ensuring the substrate remains at least 3°C above the dew point helps achieve the high-quality finish and long-term performance expected from every Aspartech installation.

As with all aspects of resin flooring installation, careful environmental monitoring forms an important part of good installation practice and helps ensure every project performs exactly as intended.