What is the most accurate method of testing for moisture within a subfloor?

All floors need to be carefully examined for moisture. The visual inspection of a subfloor is inadequate as the surface may appear dry, but moisture may still be present.

In the first instance, an indicative test using a radio frequency moisture meter offers a quick and easy method of testing moisture levels, providing an instant reading to indicate whether moisture is present. If no moisture is present, the flooring installation can proceed as planned. However, if a radio frequency meter indicates that a subfloor contains moisture, further investigation is required to enable the identification of an appropriate treatment.

To accurately assess the level of moisture in the subfloor, measurements should be made at a number of points across a floor, over a period of 4-24 hours. According to the British Codes of Practice (Sections BS 8203, BS 5325 and BS 8201 addressing the installation of resilient, textile and timber floorcoverings respectively) it is recommended that a non-invasive method is used for dampness testing, such as a calibrated digital hygrometer.

Temporarily sealed to the floor to isolate the device from the surrounding air, a digital hygrometer provides a direct reading of the RH of a small volume of air in equilibrium with the subfloor. Where RH levels are measured at below 75%, the surface is considered sufficiently dry to receive the floorcovering and the installation can proceed without further treatment. If the RH level exceeds 75%, further treatment is required.

As wood floors are particularly sensitive to moisture, F. Ball recommends a maximum RH level of 65%.However, due to the specialist nature of wood flooring, contractors should seek advice from the wood flooring manufacturer before proceeding.

Thursday, March 24, 2016