What is an acceptable damp reading?

The acceptable damp reading can vary depending on the material and the intended use of the structure. Generally, for plaster and cement screed, the acceptable damp reading is between 0.2% and 0.5%.

Damp readings can be affected by several factors, including:

Moisture Content of the Material

• Damp readings will be higher in materials that have a higher moisture content.
• For example, a damp reading taken from a wet plastered wall will be higher than a reading taken from a dry plastered wall.

Ambient Temperature

• Damp readings will be higher in warmer temperatures.
• This is because the warmer air is able to hold more moisture.

Relative Humidity

• Damp readings will be higher in areas with higher relative humidity.
• This is because the air in these areas is already saturated with moisture.

Air Flow

• Damp readings will be higher in areas with poor air flow.
• This is because the lack of air flow prevents the moisture from evaporating.

Type of Damp Meter

• Different types of damp meters use different methods to measure moisture.
• This can lead to different readings being obtained from the same material.

Calibration of the Damp Meter

• Damp meters should be calibrated regularly to ensure that they are accurate.
• An inaccurate damp meter can give false readings.

Experience of the Person Taking the Reading

• The experience of the person taking the reading can also affect the accuracy of the reading.
• An inexperienced person may not be able to correctly interpret the results of the reading.

It is important to consider all of these factors when interpreting damp readings. By doing so, you can ensure that you have an accurate understanding of the moisture content of the material in question.