Does applying Framesaver affect the Mdu Probe readings?

Treatment affects moisture content measurement, but to varying amounts

Framesaver does have an impact on moisture readings. This is due to the salt and other additives leaving a residue in the timber, affecting the electrical resistance to timber moisture content relationship that direct electrical resistance moisture measurement relies on. The amount of impact the treatment has on the probe results relies on two things:

• the time after application (the carrier of Framesaver is water). This is when the MC ‘spikes’
• the amount of treatment residue left after drying of the carrier has taken place. This is when everything has settled back down and the ‘Equilibrium’ is re-established. This is the point you should compare the results of before and after Framesaver to see if there is any EMC shift (there will also be an impact due to your building works hopefully).

We have had a lot of experience in this field as we are very intensively monitoring over 50+ houses where RotStop (a commercially available building treatment system from New Zealand House Treatment Company) has been applied into the walls while still sealed. The standard result is the probes ‘spike’, then gradually dry down. The practical impact we have seen on the Mdu Probe results from buildings that have had Framesaver applied has been varied. In many cases little to no impact has been observed in the majority of the probes. This is in fact a bad thing as this means that treatment has not penetrated to where the probe is being read from. Where the MC

has

gone up, it could still be in its ‘spike’ so keep monitoring it until it ‘flatlines’ then see if there is a significant difference in the MCs form before and after the Framesaver was applied. If there is a significant upwards shift, then install the universal probes to counter the effects of the treatment.

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