 Proper use of moisture meters in a water damage or mold remediation claim is the fundamental key to your success as a restorer. This article will give you basic knowledge on the differences between the types of meters on the market, how they work, and what information they provide.
It is well known that the two types of moisture meters on the market are Pin type meters and Pin-less meters.
Pin type meter
Pin Type meters operate on the principle of electrical resistance (conductivity). They require the operator to penetrate the material being tested. The electrical resistance of the material between the points of contact, which is influenced by the presence of moisture, is measured and displayed by the meter.
Pin type meters are capable of detecting precisely the source of moisture by penetrating through the surface at different depths. While some people are concerned about making holes in the material, this limited damage is a non-issue considering the excess damage that could occur if this moisture were left undetected.
Pin type meters also have various accessories that can be attached to provide further information about moisture conditions in hidden areas. So, the question becomes, “which meter should I use?” Many industry professionals recommend using both types of meters for the best overall detection and evaluation of moisture conditions. Ideally, using a pin and pin-less meter together will give you the fastest and most accurate results. If you are currently not using a meter at all, the meter that will give the most information on hidden moisture would be a pin type meter.
Pinless
Pin-less meters, on the other hand, use capacitance technology to detect moisture. The sensor pad, which makes surface contact with the material being tested, sends a radio frequency signal into the material.
A pin-less moisture meter is an excellent tool because you can use it to quickly scan the surface and determine if moisture is present. If moisture is detected, you must remember that the signal weakens as it moves further away from the sensor, limiting the meter’s ability to locate the source of moisture. For example, if moisture is present in insulation behind sheetrock, a pin-less meter cannot detect it. This in mind, it often becomes necessary to use a pin-less meter for a quick, overall evaluation of the job site, and then use a pin type meter to locate hidden moisture.
At first glance, a pin-less moisture meter is appealing because it does not make holes in the material. There are however, two important limitations to remember when using any pin-less moisture meter:
1. Penetration depth is limited –ranges will be from about ¼” to ¾” maximum depth depending on the meter.
2. Surface moisture will affect your reading. The affect of surface moisture varies among the different pin-less meters available on the market, and it is important to have a basic understanding of these nuances when looking for a meter.
Accessorize Accordingly
Here are some accessories that can be used with a pin type meter, making them even more useful for checking materials such as studs, insulation behind drywall, sub floors, behind baseboard mold and trim, in books or documents, and behind ceilings. The list goes on. Most of these attachments have insulated probes or blades with exposed tips, allowing the operator to penetrate at different depths, therefore picking up moisture only at the exposed tips.
• Slide Hammer - The contact pins on the slide hammer have insulated shanks so that only the tips are exposed. The pins make contact with the material at their uncoated tip and provide much more accurate readings of moisture content at various levels of penetration. This feature allows you to penetrate through flooring to a concrete or plywood sub floor.
• Deep Wall Probe - Features 4” insulated pins for use on insulation or any tests where deeper penetration is required. This probe is also an effective tool for checking synthetic stucco clad structures.
• Blade-type Electrode - Two 5'' long blades, bent to a 35° angle Teflon coated with exposed tips to check behind trim and baseboard molding. This type of electrode is also a great tool for checking moisture in books and documents.
What do the numbers mean?
Both pin type and pin-less meters are equipped with different scales that give the operator the flexibility to measure different materials. Keep in mind that depending on which scale you use, the meter readings will provide different information, not all of which will be displayed in %MC. Most of the meters on the market feature a wood scale and a reference scale. Delmhorst Instrument Co. is the only manufacturer to offer meters with a calibrated drywall scale.
Since the technologies used in a pin type meter and a pin-less meter are completely different, it is important that you do not try to make direct comparisons between the readings. It is also important to recognize that there are not direct correlations among the various scales from manufacturer to manufacturer. Below is an interpretation of the different scales and readings.
Wood - Most moisture meters have a scale that is calibrated on wood, covering a range between 6% and 40% moisture content, depending on make and model. When measuring wood products such as flooring, framing material, sheathing and furniture, use the wood scale and take the reading as %MC. Because the electrical characteristics of different species vary, some species may read differently at the same moisture content. All Delmhorst models come with a wood species correction chart or include built-in species corrections. With the built-in corrections, the operator can change the meter setting to a particular species to obtain a corrected reading. However, in most cases, the reading can be taken at face value on construction grade lumber.
Concrete and other building materials - The reference scale reads from 0-100 (or 0-300 depending on make and model) and is used when testing any building material such as plaster, concrete, brick, insulation, etc. Readings on the reference scale are to be taken as a qualitative indication of the moisture level. Readings in the low end of the scale indicate a “drier” condition; readings in the upper end of the scale indicate a higher moisture level in the material.
When using the reference scale, tests should be made on material samples that are known to be dry. These readings can be used as benchmarks or baseline readings against which all other readings are compared. Although the reference scale does not provide percent moisture content, they are still very useful to evaluate moisture conditions.
Drywall/Gyprock - Delmhorst Instrument Co. offers several models that include a specific scale to check the moisture content of gyprock. This scale is in addition to the wood and reference scales mentioned above.
This feature is valuable because it is calibrated for gyprock, and provides a reading in percent moisture content, offering more specific information about moisture conditions and the likelihood of mold development in gyprock. Since gyprock is an excellent source for mold to flourish, having a quantitative measurement of the %MC allows you to make more informed decisions regarding remediation.
Moisture meters – key tools in monitoring the drying process
For many years, large restoration companies have used moisture meters as an integral part of the drying process. In a water damage or disaster situation, it is important to dry out the structure properly and completely. Years of drying experience and the latest equipment will be null and void if meters are not used to verify that the structure is dry. Mold and mildew can form; structural damage will occur, and a simple water damage can easily turn into an inconvenient, costly disaster.
This article has emphasized the importance of moisture meters and has compared the pros and cons to both types of technologies. Now, it’s time to put that knowledge to good use:
1. Arrive at the job site with a meter to perform an overall evaluation of the damage. This evaluation will enable you to properly utilize your equipment for fast, complete drying.
2. Make moisture measurements every day during the drying cycle to determine if the equipment is doing its job. Adjustments can be made along the way based on data obtained from meter readings.
3. Verify the structure is dry by making final moisture checks before pulling any equipment. This last and important step allows you to sign off with confidence that the job was done right.
What about Temperature and RH?
Another factor to consider during the drying process is Temp and RH. While the actual moisture level of building materials is important, understanding and adjusting for the environmental conditions of the building envelope plays as important a role in the effectiveness of drying equipment. This in mind, measure the temperature and RH in conjunction with moisture so that ultimately, you can achieve a lower GPP (grains per pound). This will allow for dryer air, enabling the air movers and dehumidifiers to perform at optimal efficiency.
What’s next in Moisture Meters?
Manufacturers of moisture meters and thermo-hygrometers are constantly looking for ways to improve products that provide information which the specialist needs to make good drying decisions. This information is ultimately brought to the customer, instilling confidence that their home or work place is a healthy, safe environment.
Whichever make or model you choose, it is crucial to use a moisture meter in every single water damage job. Without it, there is no way to determine if the structure has been sufficiently dried to pre-loss conditions.
About the author - Paul Laurenzi is the Vice President of Sales & Marketing for Delmhorst Instrument Co. For nearly 60 years, Delmhorst Instrument Co. has been the leading manufacture of high-quality moisture meters. Today, the company serves more industries than all of its competitors combined.
|
