Use Moisture Meters to Detect Drywall Moisture: A Guide

When you’re inspecting a building, you know full well that something can look just fine on the surface but harbor trouble underneath.

Many of these hidden problems need a tool to properly assess the situation.

Moisture can often be one of these hidden problems, as it can be difficult to detect—until it becomes a much bigger issue. By the time you can see signs of water damage, it could be too late to do anything but replace the material altogether.

Since you don’t want to be caught off guard by unexpected moisture hiding where it doesn’t belong, let’s go over:

• Why drywall moisture testing is important
• What moisture meter you need to test drywall
• How to use a moisture meter properly when testing drywall

First, let’s review why it’s so important to test drywall for hidden moisture.

Why is drywall moisture testing important?

The gypsum in drywall is very sensitive to moisture. But even if the beginnings of a growing moisture issue are present, the drywall could still look fine at first glance. That’s why moisture measurement is key during an inspection.

You sure wouldn’t want to miss an area that looked to be all clear but harbored growing moisture due to a slow leak, poor ventilation, or other unfavorable ambient conditions.

These things just get worse over time, and high moisture levels could lead to:

• Mold growth and decreased air quality (which could cause health problems)
• Damage and decreased property value
• Compromised electrical systems (which could cause electrical hazards)¹
• Compromised wall insulation

On top of leading to expensive repairs, many of these problems can also pose possible health risks to your clients. Checking with a moisture meter can make your job easier and help protect your reputation as a thorough inspector interested in keeping your client’s buildings safe from potential moisture damage.

Using the right type of moisture meter can help you detect high-moisture hotspots within drywall and some other building materials.

What moisture meter will you need to test drywall?

Different kinds of moisture meters can be used to test drywall for moisture.

While there are meters specifically designed to test moisture levels in drywall, if your wood moisture meter has “relative mode,” you can also use that meter to take comparative measurements—to determine if some areas of the drywall have a higher moisture content than others.

While you may not be getting an exact measurement of the moisture level as far as numbers are concerned, this kind of relative measurement is still very informative and helpful.

Because, if you find areas with higher readings that means there could be an underlying moisture issue. And now you know where to conduct further investigation.

Both pin-style and pinless wood moisture meters can have this functionality.

Pin-type moisture meters require you to stick metal pins into the drywall to take a moisture reading, while pinless meters only require you to place a flat sensor plate against the drywall.

Many people opt for pinless meters because they’re non-destructive moisture testers. This mean they won’t have to worry about damaging their client’s wallboard with pinholes.

It’s also a lot easier and faster to check for moisture when you don’t have to drive in pins over and over again to get your relative measurements. With pinless meters, you can easily take as many readings as you feel are necessary.

Now that you know your options, let’s go through the proper procedure.

How to use a moisture meter to check for drywall moisture

Before you start taking moisture readings, you’ll want to:

1. Set your meter to “relative mode”: This setting must be active before you begin taking readings.
2. Get a baseline moisture level reading: Test a part of the drywall that you know is dry. This will be the control reading to compare with the other spots you test.
3. Take multiple readings in several different areas: The more readings you take, the better idea you’ll have of the drywall’s overall moisture condition.
4. Compare the readings: If some spots give higher moisture readings than your baseline, that could indicate an underlying issue that could grow into a much larger issue.
5. Be aware of factors that could throw off moisture readings: Make sure you’re placing the meter on a smooth, flat surface. Uneven surfaces can result in unclear readings. And if there is metal under the wall you’re measuring, that could skew readings as well.

Once you’re confident with the readings you’ve taken, you can make more informed decisions about the next steps.

What do you do if you get a high moisture reading?

First, communicate to your clients that when you use relative mode, it’s not about measuring the amount of moisture but how much the moisture content varies throughout a section of drywall.

And while these comparative moisture readings can be revelatory of potential moisture issues, they don’t provide information on the root cause of the excess moisture or how fast the moisture content is growing.

But they certainly clue you in on where to start looking for the underlying issue.

So if you get one or more comparatively high moisture readings, you can make a recommendation to your clients to look into it further.

You can prepare them to take action by telling them to:

1) Identify the source of the excess moisture (nearby pipes, windows, roof, etc.)
2) Fix the underlying problem to prevent further moisture issues
3) Bring in dehumidifiers, make improvements to the ventilation, or replace the drywall if necessary

While you may not be responsible for fixing this damage, alerting your clients to moisture hotspots can help them more quickly discover the root cause and prevent any further damage.

And you can always use your moisture meter for any follow-up testing to help ensure that potential moisture problems have been resolved.

Be the inspector that goes the extra mile for their clients

You want your clients to know that you’re on their team. You don’t just check for immediate problems—you also check for potential issues so your clients can get ahead of them and prevent potential damage.

Show them you mean business by using high-quality tools, like a reputable moisture meter that can detect drywall moisture variance.

But not all wood moisture meters are created equal. It pays to do your research on how they perform when attempting to detect moisture issues in drywall.

We recommend starting your research with Bessemeter’s pinless digital moisture meters. They can measure at different depths and allow for easy calibration.

What’s more, their relative mode allows them to compare the moisture levels of a variety of building materials in addition to drywall. This makes them a versatile, all-in-one tool for inspectors.

They can be the perfect tools for DIYers or anyone working in woodworking, home inspection, or home improvement.