Moisture Meter Basics

Every restorer needs a moisture meter! These are one of the most important tools used on a water damage restoration project. They allow us to verify what’s wet, how wet it is, if it’s drying, and if it’s dry. 

Our job as restorers is to return the property to pre-loss condition, but it also includes documentation of what was done, and that it was done right. The only way to verify water damage restoration was completed and the dry goals were met, is to use a moisture meter.

Moisture Meter

What is a Moisture Meter?

Simply put, a moisture meter qualifies if materials are affected by moisture, and quantifies “how much” moisture is in the material. In other words, it’s a meter to check for moisture. 

There are several types and manufacturers of moisture meters. When choosing a meter, you should get one that is good quality. We recommend Delmhorst, Protimeter, or Tramex, or Flir. Stay away from the cheap meters at the home improvement stores or online. Side note, when you buy more than one meter, or purchase additional meters for your company, buy the same brand and model (if possible). Having the same meters will make it easier for water damage checks to be completed since the same meter should be used throughout the job. If everyone is using the same meter, you can be sure the correct meter is being used for the check dry!

What are the different types of moisture meters?

There are two types of moisture meters: invasive and non-invasive (aka pin and pinless)

Invasive moisture meters

Non-invasive Moisture Meters

Invasive or pin moisture meters have metal “pins” that are inserted into the material. These pins are referred to as pins, probes, or electrodes depending on the manufacturer. Some meters have pins built in, and some have pins that can be attached to the moisture meter, allowing you to use multiple types of pins with one moisture meter. 

 

Pins come in different lengths and are used for different materials. There are short pins used for drywall, pins on a slide hammer for lumber or hardwood, longer pins that go through drywall to check insulation, and many more. 

Invasive moisture meters give a Moisture Content (MC) reading, expressed as a percentage, if used on a material it is calibrated for. Otherwise, it is used as a comparison to an unaffected area of the same material. 



Moisture Meter

Non-invasive or pinless moisture meters, also known as Non-Destructive moisture meters, use a scan feature to determine moisture. Unlike invasive moisture meters, non-invasive meters don’t put holes into materials. For this reason, you will often start with a non-invasive meter to check for moisture, then if needed, use an invasive moisture meter. If you stick invasive meter pins into drywall that isn’t affected by moisture, then there are additional holes that need to be repaired. 

 

Non-invasive moisture meters typically do not give a Moisture Content reading. Instead, they use a relative scale. They don’t tell you how much moisture is in a material, only if there is moisture relative to another area of the same material. For example, if there is affected drywall in the kitchen, you can use the non-invasive scan function to check for moisture. Then you will find unaffected drywall somewhere else in the property to compare it to, let’s say in the bedroom. 

 

If we’re using a Delmhorst QuickNav, the scan mode is a scale from 0-300. On this scale 0 is dry and 300 is wet. If the unaffected bedroom is showing 40, we know that’s dry. If the kitchen drywall is showing 280, we know that is wet. Keep in mind, that the number displayed on a non-invasive moisture meter is NOT a moisture content (percentage). Each moisture meter manufacturer has a different scan mode scale. Some are 0-99, 0-300, or 0-999, check the manufacturer’s instructions to determine their scale. 

What is a Thermo-Hygrometer?

A Thermo-Hygrometer measures temperature (thermo) and Relative Humidity (hygrometer) in the ambient air. Thermo-Hygrometers come as a standalone tool that is only used for that purpose or some moisture meters have Thermo-Hygrometers built in. Meters that have both pin and pinless tools to measure for moisture as well as to measure ambient air conditions are referred to as all-in-one meters. 

Why is it important to have moisture content and ambient conditions documented?

There are a few important reasons that we document our drying jobs; 

1) to verify our process and the proper use and efficiency of the equipment used for liability reduction and billing purposes, 

2) to verify that the proper conditions were created and maintained throughout the project to promote effective drying, 

3) to verify that our materials have been dried to pre-determined drying goals based on the established Dry Standard,

4) to re-establish the value of the structure.

We must control the ambient (aka psychrometric) conditions to create enhanced drying conditions such as proper heat/energy, dew point, and vapor pressure differentials, etc. This is documented through monitoring and recording the ambient conditions of the drying chamber, as well as the air that affects the drying chamber (coming from a dehumidifier, coming from HVAC, outside air, and air in unaffected spaces of the building). Additionally, we need to monitor the materials themselves throughout the project so we know the effectiveness of the drying environment we have created. We need to know the surface temperature of the materials and to test and record the ongoing moisture content or moisture level of the affected materials to know our system is working that we have completed the project and met our drying goal, that the project is back to pre-loss condition which will not allow for microbial growth or other potential damage.

You can learn more about meters, thermo-hygrometers, and psychrometry in an IICRC Water Restoration Technician (WRT) course. If you’re ready to purchase a moisture meter, you can check out Delmhorst moisture meters.