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Expert Interview with Paul Laurenzi Of Delmhorst Instrument On Using Moisture Meters For Home Inspections

Home inspectionsAccording to an article for Homes & Gardens, moisture and drainage is the single most common problem found during home inspections no matter what the home is made of or where it’s built.

Beyond that, sometimes you can’t even see the moisture.

So how can you tell when walls, building material, or foundations have been compromised – which could lead to problems later on with structural integrity, not to mention atmospheric pollutants like mold, fungus, and bacteria?

Moisture meters are detectors that create a moisture-level baseline to allow a home inspector to analyze and contrast different sections of a home.

Delmhorst Instruments has been making moisture meters for nearly 70 years and has learned a lot in that time. Delmhorst Instruments’ Paul Laurenzi took a moment to share some basics on ways to use moisture meters during a home inspection to not only save time and money, but also giving a home inspector penetrating insights that will make them stand out from the competition, and do the best and most thorough home inspection possible.

First of all, could you introduce us to your Moisture Meters? What do they do? How do they work? What inspired the idea originally?

Delmhorst Instrument Co. started in 1946 when founder Bill Delmhorst developed one of the first pin-type moisture meters. There were leaks in the roofs and plaster walls of buildings in New York City, andbuilding superintendents needed a way to identify them for repair.

There are two commonly used types of moisture meters. Pin-type meters, which utilize the principle of electrical resistance, use wood or other hygroscopic materials as an element in a circuit by driving two pins or electrodes into it. Pinless meters use radio frequency signals to penetrate the material being tested. There is no pin intrusion into the surface of the material you are checking.

One of the main things that your moisture meters do is to establish a moisture baseline for the inspector. Could you talk a little bit about what a moisture baseline is and why it’s important?

It’s very important to establish a baseline reading – or dry standard, as it’s often called in the water damage restoration industry. Think of a baseline as the reading that would be obtained when testing an area that is not affected by water damage. When going on a job site, we always recommend finding an area that is not affected and take that reading. That’s the baseline, or the dry standard. Then anytime you find readings that are higher than the baseline, you know there is more moisture in that particular area.

Even though moisture meters have scales that are calibrated for wood or drywall, some moisture meters use a relative, or reference scale. This type of scale is not calibrated to any particular building material; instead, it provides comparative readings that go from 0-100, 0-300, or 0-1000, depending on the make and model of the meter. The use of the baseline reading becomes even more important if you are taking readings on a reference scale.

A baseline or dry standard isn’t necessarily the same reading on all materials, or even within the same building environment. I often use my office as an example using the SCAN mode on our Model TechCheckPlus, which features a reference scale that reads from 0-300. I have wallpaper in my office and I obtain a reading of 55. When I move to another room in our building that has painted drywall, I obtain a reading of 35. This illustrates two things. First, different wall covering in the same building can yield different baseline readings. Neither room in this example has water damage, but the readings are different. Second, if there was water damage and I obtained a reading of 150 in my office in another area, that would be an indication of elevated moisture levels. Comparing readings to the baseline help the inspector determine the location of higher moisture levels. Then we recommend using a pin-type meter with a calibrated scale for drywall, in this case, to obtain more precise readings.

Another main usage of your moisture meters is after a flood to determine if there’s excessive moisture in the foundations, walls, ceiling, or roof that might not be visible to the naked eye. Why is this important? What are some things that can come about from having moisture in the walls and foundation?

Using a moisture meter to find “hidden moisture” (for example, moisture that may exist behind drywall in the wall cavity), is the only way to determine how to remedy the situation. Both drywall and wood materials can tolerate a certain degree of water damage as long as they are dried out properly. If moisture remains, things like dry rot, pest infestation, mold growth, and general loss of structural integrity can occur. Relying on a visual inspection without using a moisture meter will only cause more extensive problems down the road.

This article for Homes & Gardens claims moisture and drainage to be the most common defect detected during a home inspection. Is this true in your experience? What are some things a home inspector can look for to prevent moisture damage, rather than repairing the damage?

While poor drainage is certainly a common cause of moisture intrusion, there are lots of issues that can be the culprit. Many home inspections are performed prior to the sale of a house and, unfortunately, inspectors often find actual damage rather than just a situation that could possibly result in damage. Still, an inspector should keep an eye out for:

  • Landscape beds, stoops and walkways that are pitched toward the house
  • Poor flashing near chimneys, skylights and other openings
  • Water stains or spots on drywall, which could be an indication of either an active leak or previous damage
  • Floor joists in basements and other framing material

Your meters feature built-in species correction capability. What does that do? What are some possible applications of this feature? Will it work with other building materials like stucco or adobe?

When using a pin-type meter, all species yield different readings at the same moisture content. This is due to the fact that the electrical characteristics of different wood species vary. Delmhorst uses the USDA standard – Douglas Fir – as the basis for all calibrations.

When using a Delmhorst meter on other species, either refer to the species correction chart or key in your species into one of our microprocessor-based meters for an automatic correction.

Pinless meters also yield different readings for different species. However, instead of electrical characteristics affecting the readings, wood density affects the readings. Refer to the species correction chart enclosed with your meter, or use the internal species adjustment feature, depending on which model you have, to adjust the readings accordingly.

For general building inspections, or where you don’t know what species of wood you are testing, we recommend setting the meter to Douglas Fir, the default. Because inspectors and restoration contractors use the baseline or dry standard, it is less crucial to adjust for variations in readings cause by different species; as long as when you compare readings to the baseline, you make sure the meter is always on the same setting. However, for dry kiln operators, furniture and flooring manufacturers, and flooring installers, species corrections become more important because a precise measurement of %MC is typically required in those applications.

For measuring stucco or adobe, we recommend using the reference scale since there are no calibrated scales for those materials.

Another feature your moisture meter features is an adjustable alert when you’re reached a pre-determined moisture level. What are some different circumstances where this could be useful?

I think the adjustable alarm setting is one of the best features of our products. If we refer back to the importance of establishing a baseline reading, and comparing all other readings to it, the adjustable alarm is invaluable. Once you have established a baseline, set the meter to that number. Anytime the meter reads above the baseline, it will alert you. Other moisture meter manufacturers have alarms that are factory preset to an arbitrary number. These are less useful than an adjustable alarm because the preset value is normally not representative of the baseline or dry standard at a particular job site.

You’ve also written a book, Moisture Meters 101, giving inspectors everything they need to know to become an expert on moisture meters. What are some topics you touch on in your book? What does being a moisture meter expert entail?

The eGuide, Moisture Meters 101, is full of useful information about how to use a meter in different applications. It covers a broad range of topics including:

  • Signs of Moisture in Homes and Businesses
  • How Professional Restorers Tackle Moisture on the Job
  • Overview of how moisture meters and thermos-hygrometers work
  • Tips for getting the most out of a moisture meter
  • Countless Applications for Using Moisture Meters
  • Ten Benefits of Moisture Meters You Never Knew About

Delmhorst has written many other eGuides that are available online, each of which brings valuable information to the table. It’s difficult to define what makes someone a moisture meter expert. However, we believe that by offering our customers education about not only the operation and use of a moisture meter, but practical tips to use on the job site, we are helping the industry as a whole.

Delmhorst features a wide array of different kinds of sensors and meters. How should someone go about deciding which one is right for them? Do you have a basic unit that is particularly popular with home inspectors?

Our experienced customer service team is dedicated to assisting customers choose the right meter for their particular application and budget. Our best-selling model is the BD-2100 package, which is great for measuring a variety of building materials. Because the BD-2100 features a wood scale, a reference scale, and a drywall scale, it is an extremely versatile model. Another popular model among home inspectors is the TechCheck Plus. This model offers the same features as the BD-2100, plus a pinless mode for quickly assessing a job site without penetrating the material. Delmhorst has the widest assortment of electrodes and accessories that provide even more flexibility for more demanding or specialized applications.

It’s been said that exterior testing can’t be done in the rain or very extreme cold temperatures. Can you elaborate a little why that is? Are there any other conditions that might negate a moisture test?

The main issue with testing in the rain is that surface moisture affects meter readings, even if the material has less moisture in its core. Non-insulated pins, like the ones mounted on top of our moisture meters, measure the wettest fibers. This means that even if a non-insulated pin is inserted its full length into material, the reading obtained will be that of the surface, and will not be representative of the overall moisture condition of the material.

If the material isn’t soaking wet, an inspector can use an electrode with insulated contact pins, where readings are taken only at the tip of the pin. The coating on the shaft of the pin protects the pin from making contact with the surface moisture, therefore allowing the inspector to identify the true moisture condition of the material itself, not just the wet surface.

With respect to extreme cold temperatures, as long as the wood is not frozen solid and remains conductive, a pin-type meter will give reliable readings. However, most instrumentation, unless specifically designed for extreme weather conditions, will not work well in constant sub-freezing temperatures.

How much time and money does a home inspector stand to save from using your products? What about some things that wouldn’t be possible at all without using one of your detectors?

It’s hard to say exactly how much an inspector will save by using a moisture meter, but I like to look at it as an inexpensive insurance policy. If you think of how much it costs to replace hardwood flooring or repair damage caused by a leaky roof, a moisture meter will pay for itself many times over with just one claim.

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