Even if a concrete slab has cured, it is never completely free of moisture. The porous nature of concrete allows moisture below the concrete and within it to migrate up through the concrete capillaries and escape through the path of least resistance, a process known as moisture vapor transmission (MVT). Excessive MVT can cause bonding failures or flooring to delaminate.
For concrete and cementitious screeds to receive a floorcovering we know that the base must be suitably “dry enough”. This is to prevent damage to the flooring material and to ensure a proper bond with adhesives.
The F2170 procedure for RH testing of concrete floor slabs states that we should - Insert the hole liner to the bottom of the hole. Cap or seal the open end of the hole liner and any open gaps at the top of the liner per manufacturer’s instructions. Allow 24 hours to achieve moisture equilibrium within the hole before making relative humidity measurements.
Obtaining as much information about the roof as possible in advance is invaluable. A set of roof drawings or plans make moisture mapping much easier and a knowledge of the construction will make the job of calibration much faster.
The Dec Scanner is by far the simplest device to use for moisture testing and leak detection of a flat roof, however even a small amount of training can help new users to avoid simple pitfalls.
The Tramex moisture and humidity testing system for floor covering related industries has been developed to help users avoid moisture related problems in flooring and to identify the cause of problems if they do occur.