Instructor Ed Jones has over 30 years of experience in theindustry, has the title of MasterWater Restorer, is an Institute ofInspection Cleaning andRestoration Certification (IICRC)-approved instructor, and hasserved on the S500-2021consensus body committee todevelop the most recent standard.
The first thing to remember when using electrical moisture meters is that most of them are only calibrated for wood, not other materials like drywall.
What this means is simple: if you do not record the type, brand, and model of moisture meter used to take the drywall readings, then your drying logs will not prove that you dried the drywall.
In my ASD classes, I demonstrate this by taking two “yellow” moisture meters.
When I ask technicians what meter they used, the most common answer I get is, “The yellow one.”
For the demonstration, I use the older style Protimeter SurveyMaster and the Delmhorst BD-10 meters. Both meters are yellow.
I then take penetrating moisture content readings of drywall in the classroom, which is not wet, to obtain a dry standard reading.
A dry standard is basically the moisture content reading of the material before it got wet, or what its normal equilibrium moisture content, also known as EMC, would be.
This is important because it helps set an acceptable drying target or goal.
At our flood house in Springfield, Ohio, called the Disaster Recovery Learning Lab, or DRLL, the drywall is typically around:
I then ask my students:
If we get two different moisture content readings on the same material, at the same location, at the same time, with two different moisture meters, which meter is right?
The answer is: both of them are right.
Neither meter is calibrated for drywall, and the readings are relative or qualitative, not quantitative.
That means if, on day two of drying, your drywall moisture content reading is 15%, the interpretation depends on the meter being used.
If you are using the BD-10, you may be done drying.
If you are using the Protimeter SurveyMaster, you may still have more drying to do.
Confusing, right?
That is why you must always record the type, brand, and model of the moisture meter used to take the readings.
To add to the confusion, many technicians rely almost entirely on a non-penetrating, non-invasive, or pinless moisture meter.
The common excuse is:
“We don’t want to put holes in the drywall.”
I call the pinless or non-penetrating moisture meter the “lazy man’s meter” because I often see it used exclusively on all materials with no penetrating moisture content readings provided.
If you or your company could be blamed for incomplete drying or causing mold in someone’s home or business, then you must take penetrating, invasive, or pin moisture content readings when possible.
This should include photos of your final readings.
If the customer does not like the tiny holes left by the pins of the penetrating moisture meter, those can usually be easily remedied with a little spackle paste.
A non-penetrating moisture meter can still be useful.
I typically recommend using the non-penetrating meter first to scan the wall right above the baseboard at its lowest point along the entire length of the wall in areas of concern.
That is where the wall is most likely going to be wet.
Then, follow up in the area where you get the highest non-penetrating moisture reading with a penetrating moisture meter.
This allows you to obtain a more conclusive moisture content reading that you can photograph and add to your documentation.
This is especially important for final readings because those photos help prove that you left the drywall in a state that would inhibit microbial growth.
Remember, non-penetrating moisture meters can give false positive readings.
False positives may come from:
This is another reason why penetrating readings are so important when possible.
A pinless meter can help you locate areas of concern, but a penetrating meter provides stronger documentation.
Your moisture content readings should also be shown on a moisture map.
The moisture map should identify where readings were taken and should correlate with your drying records and photos.
This helps materially interested parties understand:
A clear moisture map makes your drying file easier to understand and easier to defend.
To strengthen your drying logs, include photos of:
These photos help prove that you reached your drying goals and left the drywall in a condition that would inhibit microbial growth.
In summary, use a penetrating moisture meter when taking all moisture content readings whenever possible.
The main exception is when looking for trapped moisture behind a vapor barrier, such as sheet vinyl or vinyl wallpaper, where penetrating access may not be possible.
Penetrating readings provide the most conclusive readings and help strengthen your drying logs.
The ANSI/IICRC S500-2021 states that the restorer should use the same meter on the same materials throughout the drying process and follow all manufacturer recommendations.
Taking conclusive moisture content readings on drywall requires more than scanning with a pinless meter.
To properly support your drying file, restorers should:
Good drying documentation helps protect the customer, the carrier, and the restoration company. It also helps avoid allegations of incomplete drying, causing mold, or leaving materials in an unsafe condition.
