F. Ball RAG 2026 - Online Version - Flipbook - Page 176
Moisture Measurement & Control
RAG® 2026
STEP 1 - CHECK IT
STEP 2 - MEASURE IT
Undertake an initial test for the presence of
moisture in the subfloor using a radio frequency
moisture meter such as the Tramex CMEX 5,
Protimeter MMS3 or Protimeter AquantTM.
If moisture is present, investigate further.
Confirm and accurately measure the moisture levels
present using a F. Ball DIGITAL HYGROMETER.
If the relative humidity is below 75%** it is safe to
proceed with fitting. If above 75% RH go to step 3.
WHAT IS THE PROBLEM?
HOW CAN YOU TELL IF IT IS SAFE
It was only in 1965 that it became mandatory to install a Damp Proof
Membrane (DPM) in new buildings. Where there is no DPM or in
cases where the DPM has failed, moisture can rise into the slab from
the ground. In cases of new construction the slab itself will contain
a considerable amount of residual moisture and although this will
generally reduce with time, dependent on environmental conditions,
this can cause a significant delay to building occupancy. There are
of course, other circumstances where a floor slab may temporarily
absorb water, after a flood, broken pipe etc.
In any circumstance where the floor slab contains significant amounts
of moisture, if floorcoverings are installed without precautions being
taken, the floorcovering will reduce moisture release thereby trapping
moisture under the covering with the potential to cause blisters or
even failure of the adhesive. When problems like this occur (after
floorcovering installation) there is no ‘quick fix’ other than to
undertake an expensive rip out, then to either let the floor dry or
install a Waterproof Surface Membrane (WSM) and install a new
floor covering.
The difficulty is that moisture is not always visible and estimates of
drying times can be very inaccurate. The best estimate of how long
a floor takes to dry to an acceptable level of 75% RH is at a rate
equivalent to 1 day per 1mm of subfloor thickness up to 50mm.
So typically a 50mm thick screed will take at least 50 days to dry.
Thicker floors can dry at an even slower rate than that. Given the
financial pressure to occupy a building the temptation is to take a risk
and proceed with installing the floorcovering - however, the costs of
getting this wrong can be substantial, not only in wasted material but
because occupancy may be even further delayed while remedial action
is taken.
In certain circumstances underfloor heating may be used to dry the
screen in accordance with suppliers instructions.
TO PROCEED WITH INSTALLING A
FLOORCOVERING?
Where there is a suspicion that the floor may contain moisture, this
needs to be carefully checked - visual inspection is inadequate as what
may appear dry on the surface may conceal retained moisture that is
being slowly released.
Firstly the presence or absence of moisture can be checked easily
using a radio frequency moisture meter such as the Tramex CMEX 5,
Protimeter AQUANT™* or Protimeter MMS3*. These devices are
quick and easy to use and give instant readings that indicate whether
moisture is present or not.
If no moisture is present then the flooring installation can proceed, but
if there is an indication of moisture presence, then this needs further
investigation.
Measurements need to be made at a number of points across the
floor and over a period of time to allow measurement of moisture
release from the slab. Traditionally such measurements have been
undertaken using a hair hygrometer that itself required careful
calibration immediately prior to use. This method has now been
superceded by the pre-calibrated F. Ball Digital Hygrometer* which is
temporarily sealed to the floor surface and gives a direct read out of
the relative humidity of the floor. Thicker power floated slabs will take
longer.
An alternative measurement method is to utilise a Tramex CMEX 5 or
Protimeter MMS3* in conjunction either with humidity boxes (similar to
those used with the digital hygrometer) or using moisture probes that
are inserted into pre-drilled holes in the slab.
Where Relative Humidity (RH) levels are measured at below 75%**,
flooring may proceed without further treatment. At levels over 75%
further treatment is required.
*For detailed operating instructions and information on how to interpret
results please see the relevant product data sheets and operating
instructions.
**For wood floors F. Ball recommend a maximum of 65% RH. Consult wood
floor manufacturer.
compound
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