Moisture testing in walls

Non destructive moisture testing in walls

Is moisture acceptable in drywall?

Drywall must contain as little moisture as possible since moisture related problems can cause structural damage and potential health problems.

Drywall or plasterboard is one of the most commonly used materials for walls and ceilings within a building structure. Drywall is a porous material that absorbs moisture easily. Moisture can negatively affect  drywall as its strength and rigidity can become compromised. Furthermore, elevated moisture levels can encourage microbial or mold growth which may cause health issues. 

As explained in our detailed article about acceptable moisture levels in drywall, drywall moisture readings over 0.5% Moisture Content should be considered higher than generally acceptable and require further drying or investigation and mitigation.

It is important that any moisture-related issues are dealt with as early as possible. Moisture is not always visible on the surface and can be hidden and trapped behind the drywall layer, within the building structure. 

How to measure moisture in drywall

damaged drywall

Signs of moisture in walls

By the time moisture or mold is visible, structural damage has already occurred. This can show up as blistering, stains or discolouration.

Thankfully there is a way of detecting this unseen moisture before it becomes noticable and starts deteriorating the building structure. A non-destructive or pinless wall moisture meter, such as the Tramex Moisture Encounter ME5 or Moisture Encounter MEX5, detects elevated moisture levels within a wall structure without damaging or breaking the surface.

How does a pinless moisture detector work on drywall?

A pinless moisture detector for drywall evaluates the moisture conditions within the building material using a non-destructive method based on measuring electrical impedance.

To evaluate moisture levels, a low-frequency electronic signal is transmitted into the material through the electrodes located on the base of the moisture meter. The strength of this signal varies in proportion to the moisture present in the material being tested.

The moisture meter measures the strength of the impedance current and converts it to a moisture measurement.  It is very beneficial to use a moisture meter that is calibrated for drywall as it can determine the actual moisture content percentage present and the signal penetration is determined for the density of the material.

how does a moisture meter work

How to detect moisture behind walls?

Moisture within and behind walls can be detected with a pinless moisture meter. A non-destructive moisture meter can accurately locate and measure elevated moisture levels without the need to break the wall’s surface material. 

Dual depth moisture meters, such as the MEX5 and ME5, allow the user to compare moisture levels within and behind a wall covering. The shallow-depth readings, up to 10mm (⅜”), and deep-depth readings, up to 30mm (1¼"), can be used to compare surface moisture and core moisture and eliminate the influence of the substrate when testing coverings. It can also help determine whether a moisture issue is located deeper within a structure.

Further in-situ investigation can then be carried out when necessary with insulated pins and RH probes for moisture measurement at depth. This can be done with the Moisture Encounter MEX5 which incorporates a plug-in port for pin-type probes which can be used to verify elevated moisture levels.

In addition to evaluating moisture, pinless moisture testing is also suitable for tracing and mapping the extent of a moisture issue within a wall structure, without puncturing the exterior surface. The scale of a moisture problem can be visualized with the use of moisture maps.

Moisture meters for drywall

The Tramex Moisture Encounters MEX5 and ME5 are calibrated to read moisture in drywall. The MEX5 provides drywall moisture content % readings with the optional pin probes as well as comparative non-destructive readings. The ME5 converts the pinless impedance reading into a qualitative moisture content value. 

The Moisture Encounter MEX5 is a digital, non-destructive moisture and humidity meter, calibrated to evaluate elevated moisture levels in drywall structures. It also features a built-in hygrometer for ambient conditions and an infrared surface thermometer, which can be helpful in determining dew-point issues. The use of the MEX5 can be extended further with optional plug-in pin probes for drywall and wood moisture readings and RH probes for in-situ equilibrium RH readings. These features make the MEX5 an extremely useful moisture meter for drywall. 

The Moisture Encounter ME5 is the improved version of the well-established and trusted Moisture Encounter Plus - MEP, which has been a favourite amongst moisture professionals for many years. The ME5 provides qualitative, comparative reading results.  

Both meters offer Dual Depth and Bluetooth connectivity to the Tramex Meters App. 

  • Dual depth measurements can help determine where moisture is located in a wall structure. By comparing moisture readings of shallow and core depth, the influence of the substrate can be eliminated when testing coverings.
  • The Tramex Meters App offers the ability to save readings, create visual moisture maps of the area under test and share reports.


How to use the Moisture Encounter 5

ME5 in use

How to use a moisture meter on drywall

As the Moisture Encounter 5, ME5, provides qualitative, comparative reading results, it is necessary to first take a moisture reading on a part of the wall that is known to be dry. This reading result can then be used as a reference for ‘acceptably dry’. 

  • Switch the meter on and select the drywall scale.
  • Press the moisture detector against the wall in a known dry area and take note to use this reading as a reference for further testing. Make sure that both electrodes fully connect to the surface under test.
  • Any higher moisture readings indicate a possible moisture related issue that needs further investigation. 
  • Taking multiple readings along the wall exterior with a pinless moisture meter, such as the ME5, does not damage the wall surface and gives a good indication of the moisture levels hidden behind the surface material. 
  • The Dual depth feature of the ME5 can help localize the depth of the moisture issue from the surface material. For example if the deep reading, up to 30mm (1¼"),  shows that there are elevated moisture levels and the shallow reading, up to 10mm (⅜”),  does not show elevated moisture issues, it can indicate that the moisture problem is located further into the building structure and has not reached the surface material.
  • With the Tramex Meters App you can view readings and create a visual moisture map of your test area, showing the different moisture values in the particular locations under test. Readings can be saved and made into reports for sharing with others.


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How to be aware of false positive readings on drywall

Moisture mapping the moisture levels

Moisture mapping can help visualise high and low readings within a wall structure, especially when there is no discernible proof of elevated moisture levels.

Moisture maps are suitable for tracing and mapping the extent of a moisture issue within a wall structure, without damaging the exterior surface.

A moisture map can help locate the origin of the moisture issue by tracing the leak and monitor the drying process until acceptable dry levels have been achieved.

Moisture mapping

Creating a moisture map with the Tramex App

Moisture test inspection

The Tramex Water damage restoration kits provide the necessary tools to detect elevated moisture levels in and behind walls & ceilings and to conduct further inspection if required.

Tramex Meters has long standing experience in developing accurate moisture detection equipment for moisture related problems within the building structure. 

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