It is now recognised that surface testing of the subfloor may not determine if the subfloor is suitable for floor covering. This is because subsurface moisture tends to leach upwards to the surface over time, thereby causing adhesion and possible mould problems for floor coverings. On the 13th June 2012 the Council of Standards Australia approved the updated AS1884-2012 (Floor coverings – resilient sheet and tiles – installation practices) and for concrete subfloor moisture testing to cross reference procedures in accordance with ASTM F2170 (international standard). The means to test moisture in concrete is to determine the relative humidity - RH (moisture in the air) within the concrete slab itself in a controlled environment and after the achievement of moisture equilibrium. Concrete subfloor shall be considered sufficiently dry when measurements taken in accordance with ASTM F2170 do not exceed 75% relative humidity. It is strongly suggested to refer to the adhesive manufacturer’s recommendation for acceptable relative humidity levels for their products even if the test results are below 75%.
MCS can perform 3rd party testing for Builders, Commercial Floor Covering Company’s or other interested parties thereby avoiding any conflict of interest in the results. MCS will provide a formal report to clients of the results which are in strict accordance with ASTM F2170 requirements.
Testing and elements to consider
All MCS team members have completed the Construction Industry Safety Induction course and have these cards with them at all times. MCS can provide WMS (work method statements) and/or SWMS (safe work method statements) to our client in order for these to be assessed and accepted before commencement of work by the head contractor.
Prior to such work it is critical that:-
- Plans/Drawings for the building site is provided which includes the depth (thickness) of the concrete and displaying separate concrete pour areas (include sqm).
- Determine when the best time and access to the concrete floor would exist (e.g. ideally before internal walls due to material and personnel on site at this stage of the construction project).
- MCS will determine number of holes and placement in advance of attendance plus staging of testing if required (three for the first 100sqm and at least one additional test for each additional 100sqm or part thereof per poured slab).
- For pre-existing slabs (e.g. not new buildings) various hazards need to be considered like silica, lead and asbestos.
- Before testing occurs, the sense probes will be calibrated within 30 days of the testing itself.
Before attending building site, MCS team members would complete the required site induction meeting and process.
On site the moisture points are numbered and marked on the concrete slab using spray paint and listed on the plans provided. Depth of concrete for each point is recorded on our worksheet matching the number written on the concrete floor. Depth is calculated based upon slab thickness and the greater of this number or 60mm is written on our worksheet. A 16mm hole is drilled to the nominated depth, excess dust vacuumed and plastic sleeve inserted. Worksheet is updated for each hole. Allow 72 hours to achieve moisture equilibrium within the hole before testing can proceed. All information is progressively recorded on our worksheets as the testing is performed. When taking Relative Humidity (RH) readings, testing signage is erected to protect equipment, remove cap, insert sensor probe and allow 30 minutes to achieve moisture equilibrium. Connect the probe to the moisture meter and allow time for the meter readings to settle, record RH and temperature, wait 5 minutes and record the RH and temperature again. The RH reading must not drift by more than 1% relative humidity over this time period. If so, continue to re-test every 5 minutes until this standard is obtained. At completion, place cap back into the hole. Photo of the results can be taken if requested by the client.
Upon return to the office report is formatted as per standard and e-mailed to our client.