CFA Guest Column
Richard Catt provides an overview of the importance of testing subfloors when it comes to LVT installations.
Measuring the moisture content of a subfloor before installing any floor covering is important. Arguably more so when installing a sheet vinyl or LVT because moisture content above 75% RH will almost certainly result in failure. The options are allowing the subfloor to further dry, or alternatively apply a surface damp proof membrane or suppressant depending on the moisture content. But making that informed choice first relies on measuring the moisture condition of the subfloor.
The basic principles of moisture measurement are outlined in the CFA’s FREE Guide to Contract Flooring, (see the CFA website www.cfa.org.uk – downloads section), the relevant British Standard (BS8203) and usually documented in manufacturers recommendations. All should be consulted.
However, whilst the basic principle of needing a ‘dry’ subfloor has not changed, the understanding of moisture measurement continues to evolve. With that in mind CFA members have recently completed work on a new guidance note (GN) relating to the in-situ probe method of moisture measurement. A number of members approached the CFA as far back as December 2022 and suggested that it needed updating because a fuller understanding of that method was now available.
After initial consultation through our manufacturers and distributors committee, the CFA responded by creating a subcommittee of experts who worked on the document across the following eighteen months creating draft documents for discussion and improvement. Eventually, a final version was presented for wider approval and work was completed in the second half of 2024. The document launched in July 2024 redefines key elements for the in-situ probe method with some very carefully considered and easily digested new parameters for the main measurements and how they should be taken.
This creates a much better and clearer understanding that is summarised at the start of the document but provides all the background data and research the further on that you read. In terms of moisture measurement, and one of the most commonly used methods of testing on site, it is perhaps the biggest change in at least a decade. It brings clarity, a more practical and technically accurate understanding, and ensures consistency between the results for a surface hygrometer test and in-depth probe method.
The full document is available through the members area of the CFA website and will be integrated into the next version of the CFA Guide to Contract Flooring. Acting as supplementary information and a member only benefit in the meantime, if things run true to form, it is likely to appear in British Standards as they are updated. That would be consistent with a number of other technical innovations supported by the CFA in the past including the original introduction of the in-depth probe method into standards, and a specification for a flooring grade of plywood that is also now widely adopted.
I am delighted that the CFA could once again show its value to members and the industry by acting as the industry vehicle for debate, development, innovation and finally publication of this work. But as ever, I would like to thank and acknowledge all those from within membership that contributed. The CFA are the leading body and voice of the contract flooring industry, and our work in areas such as technical development of flooring standards showcases that position perfectly.
If you want access to this guidance note, further information about our work, or an application pack outlining the benefits of membership, please contact the CFA offices.
Richard Catt is CEO of the CFA
