Property inspections

There is no question that the expertise of the investigating surveyor is paramount in ensuring correct diagnosis.  However, diagnosis would be very difficult without using specialist equipment.  Britannia Preservation's surveyors are highly qualified and experienced, using a wide range of surveying equipment and methods.

The Protimeter MMS meter (Moisture Measurement System) is probably one of the most useful instruments for on-site investigation.  This device utilises two modes of operation for measuring moisture in building materials: 'measure-mode' and 'search-mode'.

Measure-mode readings are obtained via a two-pinned probe which is pushed into the surface of the material to be sampled.  In this mode, actual percentage moisture readings can be obtained in timber in the range of 8%-29% but are expressed as 'wood moisture equivalent' (WME) in other construction materials. While the accuracy of timber readings is without question, due to the density and water capacity of other building materials, any readings taken from these must be considered separately.

A sensor located on the back of the device is used to obtain search-mode readings.  This particular mode is used to take relative readings to a nominal depth of 15mm in solid, homogenous materials using a numerical scale in the range of   0-1000.

The Protimeter MMS meter is also equipped with sensors for measuring relative humidity, ambient air temperature, and the surface temperature of construction materials.  These functions can be used to aid diagnosis of condensation.

A Hygrostick probe has been attached to the top of this Protimeter to measure the relative humidity.  Relative humidity is the amount of moisture that the air contains at a given temperature relative to the amount it would contain if saturated at the same temperature.  The reading of 30.7% shown is very low and although relative humidity is a function of temperature, it does not become problematic until it exceeds 70%.

This Protimeter has both Hygrostick and surface temperature probes attached.  The surface temperature probe records the temperature, while the Hygrostick probe captures the humidity.  The device then uses this information to calculate the dew point temperature – the temperature at which the invisible water vapour in the air is released as condensation.  Comparing the surface temperature with the dew point temperature can determine the risk of condensation.   .

The relative humidity and temperature functions of the Protimeter MMS meter are extremely useful, but they only provide a snapshot of conditions at the time of inspection.  Because temperature and humidity vary constantly during the day, condensation might not necessarily be occurring at the time of inspection. Furthermore, it is important to establish if condensation is aggravated by inadequate ventilation or low temperatures.  For these reasons, it is frequently useful in assessing condensation to undertake a period of monitoring using condensation data logging equipment.