Applying a wood species correction to the moisture test results is necessary for ensuring accurate readings. In fact, according to M. Steven Doggett, Ph.D. LEED AP, the founder of Built Environments, Inc., wood moisture content as high as 15% can cause corrosion of metal fasteners and at 16% may lead to fungal growth. Copyright 2023 Delmhorst Instrument Co. How to Understand Moisture Meter Readings for Accurate Results, two primary methods by which moisture testing, current temperature of the material being tested, moisture meter for water damage restoration, moisture meters for water damage restoration. And would it be normal for the MC to vary from board-to-board and one end of a board to the other? That is still quite a wide range. I can only assume that the floor is installed and you are reading through the wood into the subfloor. Mold starts growing if the moisture contents reaches about 25% moisture content. Hi Ron We need an expert locally to diagnose what went wrong with our bamboo floors. The relative humidity of the concrete is then tested over the course of 72 hours. Moisture content of 11.5% for the oak is a little high for furniture grade hardwoods. Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. I checked it with my new moisture meter and had a reading of between 8-13.5%. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. Any opinions. Appreciate any thoughts you might have. We are very arid where the tops were built so I figured the tables would be just fine knowing that it is arid where they were goingbut that doesnt seem to be the case. Not using the correct procedure. Drywall scales are used to determine the moisture content of construction, home inspection, and water damage restoration industries. Great article! The reading was 22 percent on the meter. To avoid this problem, wood flooring should never be stored where environmental conditions are uncontrolled, such as garages and exterior patios. For farmers, distributors, or rangers, measuring moisture content goes a long way in protecting the quality of the hay and the safety of the person storing it. The more specific way to know would be to measure the relative humidity and temperature in your homes air and then plug the numbers into a calculator like this https://www.spikevm.com/calculators/logging/equilibrium.php This will tell you what the MC% should be based on your specific environment. However, a low-end moisture meter can be wildly inaccurate. Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors. The builder has not been helpful in addressing this issue. Reference scales can have arbitrary number ranges such as 0-255, 0-300, or 0-100. Knowing the relative humidity (RH) conditions is a must when trying to determine what a safe moisture content for wood walls is. The plywood setting is .57. The reference scale helps to provide a qualitative estimation of moisture across different types of materials. Does it mean that wood can not hold more moisture than 40%? But opting out of some of these cookies may have an effect on your browsing experience. Wood is a hygroscopic material, meaning it picks up or loses moisture based on the ambient conditions. Anyone who works with wood must know its moisture content. The acceptable moisture content in wood depends on two factors: The wood's final use. We are checking moisture levels in several areas each day. 10 14% moisture content is too high. Remember that the meter assumes it is reading timber. Well, when testing wood, you should wail for an MC below 10%. From a strictly static MC%, 16-20% MC for long duration is going to promote mold growth. The meters will tell you if soil is wet, moist, or dry at the root level, which make them especially effective for large potted plants. Thanks for writing in. Hi Ron, Great post. Wagner has a free app called WoodH2O to help you determine the proper moisture levels based on consistent humidity and temperature. Your ideal MC will also depend on the outdoor humidity levels. This happens when the moisture inside the wood reaches a balance or equilibrium with the relative humidity (RH) and temperature of the woods surrounding environment. Accuaracy is of course more important.. Thank you for the information, I use a lot of trimmed for for children toys, menu times I use rings of 1-3 inch in diameter, For these purposes I dont care for wood shrinkage or wraping, Two things are important for me that wood will not crack, and that mold wont develop. Make sure theyre aligned with the grain and not across it. Any suggestions .thanks. As it dries, you should expect slight changes in width and length. It does not store any personal data. The ideal moisture content will depend on the humidity indoors. Pinless moisture meters are even easier to use. If you want, just give me a call at 800-634-9961, ext 225. The interior was 3/4 BW the tables dimensions were 40x 70 . Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. A consistent humidity level of 40 percent will require wood to be about 8 percent moisture content. As the name suggests, drywall is meant to be dry and damp free. This app will tell you the percent moisture content that a given temperature and humidity will equilibrate to. Failure to do this will result in warping, cracking, and other problems after the construction of the wood product. ie SW=Starting weight, TW=Target weight, using T%=Target percentage My calculation ( T% X SW = TW). Unfortunately, the insulation and drywall had already been installed. Had fans and dehumidifer running for 17 days starting 2 days after leak. Thats a big difference. Stringer readings of 10-15%. The home inspector failed to report all the sewage stains on the plastic and organic growth on some of the joists have which had been exposed to moisture the whole time even though the dehumidifier has been mitigating the plumbing leaks. There are water stains on the particle board floor, but the flooring felt completely dry a few minutes after the reading was taken (I didnt see the reading being taken), the floor looks dry in the plumbers photo, the particle board flooring is not noticeably swollen, and it certainly has no flaking or other signs of disintegration or lessening to its structural integrity. The moisture content of wood is defined as the ratio of the weight of the water in the piece of wood to the weight of the piece of wood without the water. These cookies will be stored in your browser only with your consent. The purpose of acclimating is to allow the flooring to equalize to the surrounding conditions, no matter how large the room is. A normal moisture meter reading on wood ranges between 6% and 10%. I took readings of the moisture of the sub floor at the edges of the wall and it ranged from 5 to 16, problem is i cant take it in the middle of the floor unless i rip the floor out. Other than causing structural damage, too much water can result in mold growth. But opting out of some of these cookies may have an effect on your browsing experience. we had a problem with our shower curb. The cookie is used to store the user consent for the cookies in the category "Performance". Method 01: Use a Moisture Meter Step 1: Purchase a moisture meter. I don't accept paid sponsorships, my opinion is my own, but if you find my recommendations helpful and you end up buying something you like through one of my links, I could earn a commission at no extra cost to you. Another issue with a moisture meters condition that can impact accuracy is a moisture meter having low batteries. After reading your article and following comments, my question is : How much does the finish of a wood project for indoor use affect the moisture content? Different materials will have physical properties that make them react differently when tested with a moisture meter. I hope this helps. Part of the reason is that there arent set moisture reading scales for some materials. There are different types of moisture meters and each type is for a specific purpose. I suggest you also contact NORMI, https://www.normi.org, and see if they can help you locate a certified inspector near you. Everyone who works with wood needs to understand how wood interacts with moisture in the environment. Since water conducts electricity and wood doesnt, the dryness of the wood can be determined by the amount of resistance to an electrical current. I have a question. No. They were installed over existing plywood subfloor. I have a question, I have moisture in the crawl space, we insulated the crawl with closed cell, cannot get the osb subfloor below. In their warehouse, and perhaps partly also in the container. Whether the meter is in the correct reading scale mode; The temperature of the material being tested (for pin meters); Whorls in wood or other flaws that affect material density (for pinless meters); and. Hope this helps. Because pinless meters are calibrated using specific gravity as the standard for measurement, random changes in SG for a material can impact the accuracy of their moisture readings. This gives you a comparison point for future referenceallowing you to more reliably identify moisture-compromised materials. I am not concerned about a 17-20% reading since mold wont grow below about 25% MC. Again, the correct moisture content will depend on the surrounding conditions. isnt it? The cookie is used to store the user consent for the cookies in the category "Analytics". The lumber must be cured or replaced. It was such a good read. We just had a hydrometer installed in the crawlspace and it is reading 38% as of today. Softwoods, such as spruce, can have more moisture. The lumber was recently milled, although the tree had been cut months, years ago. This means the EMC ranges from 6.2% to 7.7%. This means that wood intended for interior use in this location should not only be dried to around 6% but should be kept at this moisture content both before and during the manufacturing process. Here is a bit of information to help you better understand moisture meter readings: Understanding how a moisture meter works is crucial for understanding moisture meter readings and what can affect them. One sheet of plywood is 25% next to a 2X4 truss reading 17-27%. This helps to prevent the electricity from escaping from the base of the electrodes and passing through the water. However, many building materials may have been dried down to about 15% moisture content. As a result, a moisture meter, which only evaluates dampness in the top few inches, cannot defect the MC in deeper layers and the readings with not be 100% reliable. I removed an of the foam insulation. At lower temperatures, the resistance of a material increases. Normal moisture content of wood ranges from 7% to 19%. Instead, these are just estimates where high values mean high moisture levels and low values mean low moisture levels. Brick Stone Concrete Stucco Tile Mortar Plaster Cement Mudbrick Granite As you can see, masonry can be a mix of many substances and materials. For more information, see our article comparing Pinless Moisture Meters vs. Pin Meters. Question: Just to make sure that you get accurate moisture measurements, has your moisture meter been checked for calibration? What are Acceptable Moisture Levels in Wood? Hi Ron- just purchased a home n PA and had the roof inspected which showed a leak on the plywood directly under the shingles. A normal moisture meter reading on wood ranges between 6 and 10%. There are two ways of dealing with this issue: A moisture meter with insulated pins will only release electricity from the tips of the electrodes. Thanks. Home Moisture Meters Wood Division Knowledge Base Moisture Content What Do These Moisture Meter Readings Mean? Make sure there are no leaks in the 4 area. We want to get someone out with a better reader to test the floors as well. In fact, above this point, most readings are no longer even useful. However you may visit Cookie Settings to provide a controlled consent. Wood flooring will also shrink or expand with moisture changes; even small changes can produce significant effects. Is this accurate? The floor immediately felt stronger. Ideally, you want to check the EMC in the area you will be working on your slab, along with the area it will live in. Your email address will not be published. The maximum subfloor moisture level for solid strip flooring or wide-width solid flooring is either 12% or 13%, depending on the manufacturer. The average annual relative humidity will play the biggest role in determining what the optimal MC should be. For example, if the moisture content of the delivered wood is 12% and the optimal MC is 6%, then physical problems will occur during the acclimation process. For solid strip flooring (less than 3 wide) there should be no more than a 4% difference in moisture content between properly acclimated wood flooring and subflooring materials. Hi Larry, We are a joinery company and we have a project here in UAE which is located in another part of the emirates and the humidity in that area is very high especially during summer because it is near the coastal area. There are areas where organic growth was very active to cause deep, black discolorization. My house was built in 1927. Including some high-end species like Rosewood, ebony, Mahogany, White Cedar, Bija Sal, Walnut, Gmelina, etc. When the wood neither gains nor loses moisture, we say that the wood has reached its equilibrium moisture content (EMC). What wood do you recommend that does not have a high oil/water content? Second, would the same pine slab, would it be okay to use for a side table or Kitchen island. Each piece of lumber is unique and carries physical characteristics that may include the following: knots, warping, shrinkage, swelling and/or splitting. Analytical cookies are used to understand how visitors interact with the website. The chart below will clear things up. Why You Should Use Relative Humidity (RH) Testing, Flooring, Millwork, Furniture & Cabinet Manufacturers, How to Choose a Moisture Measurement System for Your Sawmill Buying Guide, Acceptable Moisture Levels in Wood Knowing the Moisture Content, Free Download 5 Ways Pinless Moisture Meters Save You Time and Money. Any thoughts as to what the issue was with the first install so we dont have the same issue again next year after we go through a new install? My house is 24 years old. Record the reading you get and use this as a baseline. Your reading of 12.5% tells me it is workable. There are two primary methods by which moisture testing in solid materials works: Each of these two moisture testing methods has their own unique strengths and weaknesses. What should be the approximate Highest MC to prevent wood problems to include finishes? Outside of these ranges, hardwood floors might start . Did the Contractor mention anything about the structural strength of the joists? Gareth, Im not sure that the 23% MC reading is accurate; it sounds pretty high, but nonetheless, it appears as if you dont have a problem, but if you have concerns about possible mold, I suggest you also contact NORMI, https://www.normi.org and see if they can help you locate a certified inspector near you. The BD-2100's drywall moisture meter readings are accurate in gypsum to moisture content percentages as low as 0.2% and as high as 50%. The sink vanity is made from typical laminated particle board, and Ive been trying to dry it in place using a dehumidifier and sealing the area off. As the humidity decreases, the MC decreases, causing the wood to shrink. look forward to your comments. Wagners Orion series of meters are the most accurate wood moisture meters on the market. I am not familiar with the particular moisture meter the plumber was using, but assuming it is correct, that moisture content is way too high to install new flooring.
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