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Acceptable Moisture Levels in Wood – Moisture Content
Everyone who works with wood needs to understand how wood interacts with environmental moisture. If you’re a carpenter, a flooring expert, or a builder, wood’s moisture content (MC) should be a consideration in your work.
This comprehensive guide will unravel the mystery of acceptable moisture levels in wood, exploring diverse perspectives from woodworkers to builders. You’ll also learn about the tools and methods to accurately measure these levels, such as the invaluable moisture meter. Additionally, we’ll shed light on the pioneering work of Dr. Eugene Wengert, who made significant strides in this field.
- Understanding Moisture Content of Wood
- How Do You Remove Moisture From Wood?
- What are Acceptable Moisture Levels in Wood?
- How to Measure Moisture Content in Wood?
- How to Measure Moisture Content in Wood with a Moisture Meter?
- Accuracy of Wood Moisture Meters
- Moisture Content of Wood from a Woodworker’s Perspective
- Moisture Content of Wood from a Flooring Installer’s Perspective
- Moisture Content of Wood and Lumber from a Builder’s Perspective
- Acceptable Moisture Content for Wood In a Nutshell
Understanding Moisture Content of Wood
How Does Moisture Affect Wood?
Wood is hygroscopic. It gains or loses water moisture as the surrounding air’s relative humidity (RH) changes.
These varying humidity levels of the surrounding air cause wood to not only gain or lose water moisture but expand or shrink. The MC increases as the humidity increases, causing the wood to expand. The MC decreases as the humidity decreases, causing the wood to shrink. When the wood neither gains nor loses moisture, we say it has reached its equilibrium moisture content (EMC).
According to Dr. Eugene Wengert, professor and specialist in wood processing at the University of Wisconsin-Madison’s Department of Forestry, wood should be dried to a water MC within two percentage points of the EMC where the wood will be used.
If this is confusing, don’t worry. The chart below will clear things up. Notice that the EMC of the in-use location is the same as the MC:
| Humidity of the in-use location | EMC of the in-use location | Corresponding MC the wood will attain at this location |
|---|---|---|
| 19-25% | 5% | 5% |
| 26-32% | 6% | 6% |
| 33-39% | 7% | 7% |
| 40-46% | 8% | 8% |
| 47-52% | 9% | 9% |
So, using this chart, we know that in an area of the country where the RH inside a home or office is anywhere from 26-32%, both the EMC of the in-use location and the wood moisture content kept in that location will be 6%.
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.
summary
Wood must always be allowed to acclimate or come into balance with the RH of the end-use location. Failure to do this will result in warping, cracking, and other problems after the construction of the wood product.
How Do You Remove Moisture From Wood?
Kiln Drying
Freshly cut wood has a lot of moisture in it. Eventually, this internal moisture will evaporate by itself. Kiln drying is used to speed up the process.
Some of the unfinished wood you see on the market has been kiln-dried to reduce its water moisture content to around 8% so that it won’t suffer from moisture-related defects like warping and buckling. However, many building materials may have been dried down to about 15% moisture content.
Wood moisture content is always varying. It’s never constant. Wood – freshly cut or kiln-dried – is always interacting with environmental moisture.
Therefore, just because the wood is kiln-dried doesn’t mean it has lost the ability to absorb moisture. It will continue to absorb and release moisture until it comes into balance with the surrounding air.
What are Acceptable Moisture Levels in Wood?
The acceptable moisture levels of wood and lumber range from 6% to 8% for interior and 9% to 14% for exterior wood or for building envelope components within constructed assemblies.
The acceptable moisture content in wood depends on two factors:
- The wood’s final use.
- The average RH of the environment where the wood will be used.
These two factors make it difficult to say anything specific about acceptable wood moisture content. It’s more important to understand that the wood is kiln-dried down to a certain bell-shaped range of MCs. There will be statistical outliers on both the low and the high end and you’ll want to catch these by using a quality moisture meter.
How to Measure Moisture Content in Wood?
There are two main ways of measuring wood moisture content: oven-dry testing and moisture meter testing. Let’s go over the basics of each…
1. Oven Dry Testing
Oven dry testing is the oldest method for measuring the moisture content of wood. The process is time-consuming but produces accurate results if followed correctly. Here’s how it works…
The wood sample being tested is dried in a special oven or kiln and its weight periodically checked. Once the wood sample’s weight stops changing, its weight is compared to what it was before the drying process began. This weight difference is then used to calculate the wood’s original moisture content.
While oven-dry testing, if followed correctly, offers accurate results, there are a few drawbacks:
- It takes a long time – We’re talking about hours. The oven drying process must be done slowly or the wood could burn and the test results will be worthless.
- It will render the wood unusable – It often happens that oven drying over dries the wood to the point where it’s unusable.
- It requires a special oven or kiln – Most hobbyists who work with wood don’t have an oven that’s capable of producing accurate results.
These three drawbacks mean that oven-dry testing usually isn’t the option of choice for hobbyists who work with wood.
2. Moisture Meters – The Easiest Way to Measure Moisture Content in Wood
The fastest way to test the moisture content of wood is to use a moisture meter. There are two main types of wood moisture meters, pin-type and pinless.
Pin-type meters use penetrating electrodes (pins) and measure the wood’s moisture content using electrical resistance. Since water conducts electricity and wood doesn’t, the dryness of the wood can be determined by the amount of resistance to an electrical current. Dryer wood produces more resistance than wetter wood.
Pinless meters are non-penetrating and read the moisture content. Pinless meters scan the wood’s surface and cover a larger area than pin-type meters, they provide a more thorough picture of the wood’s moisture content.
Pinless meters also don’t leave damaging pinholes on the wood’s surface. This makes pinless moisture meters perfect for measuring the moisture content of things like expensive hardwood floors.
How to Measure Moisture Content in Wood with a Moisture Meter?
Pinless Moisture Meters
Pinless moisture meters are the fastest and easiest way to measure moisture content in wood. Simply press the scanning plate against the wood’s surface and receive a moisture reading.
Pin-Type Moisture Meters
The general process for using pin-type moisture meters is as follows…
- Insert the pins into the surface of the wood you want to test.
- Make sure they’re aligned with the grain and not across it.
- Turn on the meter. The electrical current will then move from pin to pin and measure the resistance encountered.
Accuracy of Wood Moisture Meters
The ASTM D4442 standard determines the accuracy of wood moisture meters. This method uses the oven-dry method and then compares the results to those obtained using a moisture meter. The difference is the moisture meter’s measurement error.
For more information, see our article comparing Pinless Moisture Meters vs. Pin Meters.
Moisture Content of Wood from a Woodworker’s Perspective
Because wood shrinks and warps as it dries, woodworkers want it to be pre-shrunk before they use it. Furniture maker Lonnie Bird weighs in,
“I don’t want the wood to shrink after I use it because the wood will warp or split.”
Bird, who runs the School of Fine Woodworking outside Knoxville, Tennessee, says he knows wood shrinks seasonally but wants to minimize the shrinkage and expansion by drying the wood to a moisture content of about 8%.
He always uses a moisture meter before working with it to ensure the wood is properly dried.
The moisture content of freshly cut wood is typically somewhere between 40-200%. If you’re wondering how wood can have a 200% moisture content, here’s how that works…
Because the moisture content of wood is equal to the weight of the water in the wood divided by the weight of the wood without the water, the moisture content can exceed 100%. In other words, the water weighs more than the wood fibers.
How Dry Should Wood Be for Woodworking?
The acceptable wood moisture content normally ranges from 6% to 8% for woodworkers who build cabinets, fine furniture, musical instruments, dishes, toys, decorative art, boat restoration, or various other wood products.
This range will vary slightly according to the geographic region because of varying RH levels.
The normal moisture content of wood (or EMC) varies from 7%-19% depending on the RH in the air.
If an interior location has an average RH of 40-52%, wood placed there will have an average EMC of 8-9%. This is based on a Wood Handbook: Wood as an Engineering Material chart.
To avoid post-construction problems, a woodworker building a cabinet for this particular interior environment would need to dry his wood to a moisture content of 8- 9% beforehand and then keep it dry during construction.
The best way to do this is to use an accurate moisture meter.
summary
Acceptable wood moisture readings on a meter normally range from 6% to 8% for woodworking. Normal moisture content of wood ranges from 7% to 19%. Be sure to acclimate the wood to desired EMC of the interior environment before you use it.
Moisture Content of Wood from a Flooring Installer’s Perspective
The National Wood Flooring Association (NWFA) has specific installation guidelines for wood flooring and how they relate to moisture content.
When determining the acceptable moisture levels in wood flooring before installation, the NWFA states that the flooring professional should establish a baseline for acclimation.
Acclimation is the process for conditioning the moisture content of wood flooring to the environment where it will be installed.
To establish a baseline for wood flooring acclimation, the installer will need to calculate the optimal moisture level of the wood by dividing the region’s high season and low season EMC.
For example, if the expected EMC ranges from a low of 6% to a high of 9%, the baseline moisture content of the wood would be 7.5%.
The installer should then check the moisture content of multiple boards and average the results. A high reading in one area indicates a problem that must be corrected.
We really can’t overstress the importance of taking plenty of moisture readings. When you do this, you not only ensure that the entire batch is okay on average, but you’re also far likelier to catch boards that are statistical outliers and could cause problems.
If the moisture content of the product is well outside the range of optimal MC, the wood flooring should not be accepted because it will lead to shrinkage, bowing, cupping, and other physical problems.
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.
To avoid this problem, wood flooring should never be stored where environmental conditions are uncontrolled, such as garages and exterior patios.
As a general rule, with geographic exceptions, wood flooring performs best when the interior environment is controlled to stay within an RH range of 30% to 50% and a temperature range of 60 to 80 degrees Fahrenheit.
The ideal humidity range in some climates may be higher or lower. For example, from 25% to 45% or from 45% to 65%.
NWFA has a chart that indicates the moisture content of wood at any given combination of temperature and humidity. The EMC in the recommended temperature/humidity range coincides with the 6% to 9% range used by most flooring manufacturers during the manufacturing and shipping process.
Although some movement between 6% and 9% can be expected, wood flooring can shrink or swell more dramatically outside this range.
Installers should also measure the moisture in wood subfloors and concrete slabs as they can also affect wood flooring. Depending on the manufacturer, the maximum subfloor moisture level for solid strip flooring or wide-width solid flooring is either 12% or 13%.
The National Association of Home Builders’ Green Home Building Guidelines for solid strip flooring and wide-width flooring are as follows:
- 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.
- For wide-width solid flooring (3” or wider), there should be no more than a 2% difference in moisture content between properly acclimated wood flooring and subflooring materials.
summary
Wood flooring installers typically want the moisture content of their wood to be between 6% to 9%.
Free Download – 5 Ways Pinless Moisture Meters Save You Time and Money
Moisture Content of Wood and Lumber from a Builder’s Perspective
For most areas of the United States, acceptable moisture levels of wood and lumber can range from 9% to 14% for exterior wood or for building envelope components within constructed assemblies. An MC in this range is considered sufficiently dry for exterior in-service wood.
Using wood with a moisture content above 14% isn’t recommended because it may have detrimental long-term effects on the construction.
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.
When it comes to the moisture content of plywood or dimensional lumber, an MC of 17% to 19% reduces the overall strength of plywood, and an MC of 20% or more reduces the strength of dimensional lumber (i.e., lumber cut to certain predefined sizes, such as 2x4s).
A study by Imamura and Kiguchi (1999) showed that wood moisture content over 20% can cause a 5% loss of nail shank diameter in four years and a projected 25% loss in 30 years. The same study showed a 40% loss in joint strength and concluded that a 20% MC may significantly compromise shear resistance of exterior walls.
When exposed to a constant RH, the moisture content of wood or lumber will come to equilibrium with its environment, resulting in an EMC for that species of a wood-based composite.
The EMC of wood or lumber exposed to an outdoor atmosphere varies across the U.S.
For instance, Seattle’s EMC ranges from 12.2% to 16.5%. In the Midwest, the EMC of wood or lumber in Des Moines, Iowa, ranges from 12.4% to 14.9%.
In contrast, Las Vegas in the drier Southwest has much lower EMC percentages than most other U.S. cities. The Las Vegas EMC of wood or lumber ranges from 4.0% to 8.5%.
Acceptable Moisture Content for Wood In a Nutshell
Based on common guidelines or recommendations, the acceptable moisture levels for wood are as follows:
- Wood objects used indoors: 6-8%
- Wood flooring: 6-9%
- Construction: 9-14%
Remember that a wood’s acceptable moisture level will depend primarily on how it will be finally used and the average RH where it will be finally used. The wood species and the thickness or size of the wood may also factor in.
Using a moisture meter before painting can help you determine the moisture content of the wood. The interior wood moisture level should be 12% or lower before painting.
In all cases, determining the acceptable moisture level of wood requires using an extremely accurate moisture meter.
Failure to allow the wood to acclimate or come into balance with the RH at its end-use location could result in any number of moisture-related problems after the wood product is constructed. These include warping, cracking, buckling, diminished wood strength, corrosion of fasteners, and even fungal growth.
If you’re still new to wood moisture meters we have a guide on how to use a moisture meter that can better help you get started.
Elevate your woodworking and construction projects with our Free Wood Moisture Testing Webinar. Gain invaluable insights from industry expert Jason Spangler in just one hour. Reserve your spot now!
Larry Loffer is a senior technician at Wagner Meters, where he has over 30 years of experience in wood moisture measurement. With a degree in Computer Systems, Larry is involved in both hardware and software development of wood moisture measurement solutions.
Last updated on May 15th, 2024
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I tried to reply your answer on my last question, but simply cannot click the replay button.
Thank you so much Larry for your quick response. We had internal discussion about this since the Particle Board is not listed in the manual species, but MDF is mentioned. We not sure because Partice Board was made from wood particles and glue. And technically it not real wood. Currently we using Wagner Orion 910 as daily MC Meter for incoming material checking.
If the species setting is not available, we can use method of Denisty Oven Dry test first right, as reference of MC species setting?
Sincerely,
Inez.
I tried to reply your answer on my last question about can or not Wagner MC Meter to read moisture content in Particle Board and MDF, but simply cannot click the replay button.
Thank you so much Larry for your quick response. We had internal discussion about this since the Particle Board is not listed in the manual species, but MDF is mentioned. We not sure because Partice Board was made from wood particles and glue. And technically it not real wood. Currently we using Wagner Orion 910 as daily MC Meter for incoming material checking.
If the species setting is not available, we can use method of Denisty Oven Dry test first right, as reference of MC species setting?
Sincerely,
Inez.
Hi, can we use the MC meter to read moisture content of Particle Board or MDF?
Yes, the meter comes with a quick guide to address each setting for MDF, HDF, particle board, etc.
Thanks for sharing thsi insightful information
Thank you very much, Larry, this is very useful.
Hi Larry.
Thanks for answering all these questions. It’s been a great resource for me!
Curious your thoughts on whether or not to rent or purchase a humidifier in my situation.
Yesterday, in our pantry, I discovered a 2.5 gallon Arrowhead plastic water container on the floor had been leaking.
Anywhere from 1.5 – 2 gallons were gone from it. I’m not sure whether it was a slow or fast leak, but I’m guessing slow-ish as the area of wood that was soaked wasn’t larger than the container.
I directed a fan onto the area (it’s the corner of the pantry) and in about 12 hours the 1’x1′ area looked drier if not dried on the surface. I bought a moisture meter and found that the area is anywhere from 15% up to a very small area in the corner around 24%/25%. Will leaving the fan on for the next few days solve the issue, or should I rent a humidifier to keep mold growth from happening.
They are engineered wood floors (Old Masters Garrison II) installed 7 years ago. Plywood subfloor installed on top of vinyl flooring with wood floors glued to plywood subfloor. Excellent installers, if that data point helps any.
Thanks for any help!!!
Best,
Paul
Paul,
If you don’t know when the water container started leaking, mold growth may have already occurred under the flooring.
Fortunately, the wet area is small. I would keep a fan on it for a few days if the flooring is not crowning.
Option B, since it’s in the corner, and you notice some damage to the flooring, you might want to consider lifting up the flooring to check the subfloor.
HI Larry,
We recently moved to central Ohio in a brand new home and had mold issues due to the sump pump drain hose being damaged and improperly sloped. As a result we had inital mold and some of the framing studs in the basement measuring as high as 70% mositure.
After corrective action, the farming studs moisture levels have dropped to 18-25% range, with a couple of exceptions reading 26 and 29%. The local tech told me that treated studs would typically have about a 5% higher reading than untreated studs. What should the typical moisture reading be for treated construction studs? What is the tolerance range?
Thank you,
Tony
Hi Tony,
Treated lumber typically has metallic components which makes any moisture meter read high even though the actual moisture content is lower. Pin and pinless moisture meters will respond with a higher reading. It is difficult to say exactly how much because it depends on the amount of treatment applied. The 5% suggested by the Technician is a reasonable average. Mold on lumber grows when moisture contents exceed about 25%.
To answer your question, you need to measure less than 25% if the treatment does not contain metals and less than 30% if the lumber treatment contains metals such as aluminum oxide etc.
Larry:
We live north of Houston in Montgomery, TX. While on vacation we had a refrigerator ice machine line leak. We have reclaimed hand scraped Elm floors put down in 2013. I bought a Kobalt pinless digital moisture meter, calibrated it and put in on grade 3. We had fans and dehumidifiers running for 4 days, taking up the baseboards and molding about 36 hours ago and drilling holes in the sheetrock. The main area affected is a hallway. On my floor that was not affected it reads 10.5 -11.0. Right now the affected floor is anywhere from 11 to 14. The restoration company wants to rip up the floors but I know I cannot match them and they are high end floors glued direclty to the slab. Plus I have read that is water resistant and good choice for flooring. I got approval from insurance to run the fans for 5 more days.
Any suggestions as I want to save these floors? Plus am I reading this meter right? I put it on grade 3 based on their Elm desinty of .58.
Thanks
Bill
This is the first time I’m coming to know that there are acceptable moisture levels when it comes to wood and whatnot. Who knew that so much detail goes into the wood, right?
Hi Larry – Thanks for your expertise! We had a leaking dishwasher several months ago. We replaced the dishwasher and the plywood subfloor dried up. Dishwasher isn’t leaking anymore and have checked several times to make sure. After the plywood dried, however, there is still one spot about the size of a baseball that is still reading around 17-20%. Our house in on a crawl space in GA, and it’s been pretty humid the last couple days which is when it read a little over 20%. Outside of this small 4”x4” area, the moisture rating returns to 12-15%. I’ve been monitoring this area for several months and haven’t seen any mold growth, but it just seems to have found balance at around 17-20% in this small area. Is it OK to leave it alone at this point if it’s a small spot or should something more be done?
Hi Josh,
I am not concerned about a 17-20% reading since mold won’t grow below about 25% MC.
A possibility is that this baseball size spot has a large knot or is higher in density, which can cause higher readings even though the MC is the same as other areas. Make sure there are no leaks in the 4” area.
HI Larry,
I have Suar wood from Indonesia and want use to indoor furniture, how range the Moisture Content allowance for this wood.
Characteristic of this wood easy to absorb of water and have large open pore.
Looking forward to having your feedback.
Thanks.
Yana A.
Yana,
The ideal moisture content will depend on the humidity indoors.
A consistent humidity level of 40 percent will require wood to be about 8 percent moisture content.
A consistent humidity level of 70 percent will require wood to be about 13 percent moisture content.
Thanks.
Simply put, the post offers some useful information. I appreciate you sharing this important information with us at this time. Please provide us with regular updates.
Hi Larry,
I’ve been following your in depth blog on moisture meters for around 1 year now. Very educational! I have one question with regards to pinless moisture meters and wallboard/Sheetrock. I purchased my newly built home that has to meet all the new energy efficient standards and will be 2 years old this coming month.
While playing around with my pinless meter and checking the interior East and west walls on hot days, I notice the moisture content being very high 60% mc to off scale. Interior walls non-insulated at around 7-8% mc. The interior home conditions are, AC running at 68-70*F. Exterior wall condition 104*F as checked with an IR thermometer of East wall not in the sun. Outdoor temp is 99*F.
Is this normal? Am I possibly getting false positives? This pinless meter is accurate, I’ve got 2 other pin moisture meters and all 3 of them read within only 1-3% difference as checked on wood structures.
Thoughts ideas?
Regards,
Bob
Bob,
That’s a big difference.
Readings can be elevated if there is a stud directly behind the sheetrock.
I can’t speak for other pinless meters but our Wagner meters are not sensitive to the temperatures you indicated.
Perhaps there is something different about the East and West walls. You may be picking up something behind the sheetrock.
HI,
I live in michigan (humid summer, long cold winter).
I have been testing the bottom stud/sill board of an exterior wall on a slab of an old house that exposed in order to put a floor in. The MC varies from 7% – 13.5% around the exterior door on dry days and 10%-16% during rains. Specifically in the first 3-4″ on one side of the door is 11%, then drops to ~8%. To the right, 13.2% in the same distance and also drops to ~ 8% after.
Indoor humidity is around 50%, indoor temps around 70 degrees. So chart would indicate around 9%.
My meter tells me anything above 12% is ‘wet’ but I cannot find any source of leaking or signs of water. I am not sure if this is pressure treated wood given it’s an exterior wall and if that affects what these numbers are.
My thought is maybe to get one of your meter for greater accuracy? I think mine is +-3%
Is it possible being near the door just means greater humidity and there isn’t actually a leak?
Would it still be 9% for pressure treated wood?
Hi Emily,
Please call me, 800-634-9961, ext. 225
Thanks!
If the MC of plywood is above 20%, can it be redried in a kiln or would that harm the glue?
Hi Doug,
I would not recommend re-drying finished plywood. Because of the different materials involved, they will react differently to high heat, thus giving you an un-even plywood surface.
Does coating wood with oil stabilize the moisture content in wood?
Mukund,
Oiling the surface does not control the moisture in the wood. The wood will still react in humid or dry conditions. Thanks for the question.
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?
Richard,
It depends on the size of the project, but anytime you put a waterborne urethane on the wood you are adding moisture to your project. Most of it will dissipate.
Thanks for your question.
Great article! 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
I use pure tung
For these purposes I don’t care for wood shrinkage or wraping
Two things are important for me – that wood will not crack, and that mold won’t develop
You wrote that 15% humidity may induce mold?
I’m looking for the % number that will be my upper boundary for oil application
Would 12% be ok?
Should it be less? 10?
Ideally I’ll wait until reaching final drying but sometimes I need to use wood before that point
(I’m using pin type humidity measure)
Hello,
The ideal moisture content for hardwoods is between 6% and about 9%, depending on the ambient conditions around the wood.
15% is too high, at least for hardwoods.
Softwoods typically have higher moisture content than hardwoods. 12% is good for softwoods, but again, it depends on the relative humidity and temperature where the finished product will be kept. As far as the oil finish, the manufacturer of the oil will specify the correct moisture content for an application.
Hi and good day , I would like to find out what r the right temperature readings for workable wood slabs in South Africa specially Matumi wood slabs
Carlos,
I believe you are asking for the percent moisture content (humidity) of South African woods. Good moisture content for hardwoods is 6% to 9% moisture. Good moisture content for softwoods is 10% to 14% moisture.
I did not find any information on Matumi. Does it have another common name?
Great article, thanks for the info. I live in Atascadero CA and had a coastal red oak tree cut down this past summer. I had it milled into 2.25” slabs and I stacked it on a deck area. I’m planning on using some of it to build a new front door for the house and was wondering what MC I should be shooting for. The door is NE facing and protected from direct Sun light and rain by a porch roof. Summers are hot and dry while winters can be cool. I was thinking 10% MC would be ok but after reading your article I’m not sure. Do you have a suggestion?
Joe,
Standard moisture contents for hardwoods are 6% – 9% MC. This is for furniture-grade hardwoods. Your ideal MC will also depend on the outdoor humidity levels. You can use our free APP called “WoodH2O” to help you decide on the best moisture content.
Dear Larry ,
I would like to load eucalyptus and pine wood logs to India . ( 55 days transit by sea)
What should be the moisture content while loading in Containers?
Shamir:
Thanks for the email. I’m not sure I can really answer this question. This would depend on the expectations of the person receiving the product in India, how large of diameter the logs are, and some average estimate of what the conditions would be inside the container during the 55 days. Even at this, the estimate would be the high end of MC% prior to shipment, but only rough estimate.
I had several of the varnished decorative hardwood laminated ply panels replaced in the lounge on an air conditioned luxury yacht. Subsequently the woodgrain has reflected in the previously mirror-finish, only on the new panels and we suspect moisture content issues in the wood before it was varnished. The wood and varnish appear otherwise pristine, uncracked and not bubbled or clouded in any way. There is no balancing layer on the reverse of the panels which might obstrust breathing of the panel. Please commenr?
Wood is used to clean model railroad tracks. What wood do you recommend that does not have a high oil/water content?
I read your article and really like it. Timber logs & Lumber into India company remained actively involved in harvesting and sale of Hardwood logs of Indian origin. Including some high-end species like Rosewood, ebony, Mahogany, White Cedar, Bija Sal, Walnut, Gmelina, etc.
Hi,
I am shipping teakwood furniture from Indonesia to California. The wood has been kiln dried and packed in corrugate. The shipping time is approximately 45 day in a 40′ container to the west coast . How would be the best way to prevent mold from growing on the furniture. They are putting desiccants in the container to absorb the moisture but we feel its going to be a long time enclosed in the container without any air circulation. Do you have any recommendations on how to prevent mold from getting on the wood?
Howard,
Congratulations on your new furniture. With regard to mold growing on your furniture, I would have to defer you back to the shipping company as they have more experience dealing with these types of issues.
We appreciate you writing in, best of luck!
I found your website at just the right time. A termite repair company (also licensed contractors) told me that I needed to replace the planks on my second story deck. I had a redwood deck, and they replaced it with Douglas fir (without my approval, but that’s another issue). The wood looks awful, and the staining the did is even worse. My question for you is, now that it is stained, can I still get an accurate MC? They delivered the wood one day, and began to stain and install it over the next two days, finishing on the 6th day. They are returning to remove one plank and take it back to see what they can do to meet my satisfaction. I’m still not sure that whatever they do will produce a good, long-term result, but I need to know what they should be doing to the wood. Thanks for any help you can provide!
Mari,
Yes, the wood can still be read for MC with a stain on it. Best of luck with your project.
Thanks for the article, really appreciate the info!
with the spring thaw, i was one of the lucky ones that got water in my basement. We found the problem and the leak was resolve quickly! The water was there for at most 6 hours, then we vacuumed it all and started the process of drying. The problem is some of the water made its way under the basmenet bathroom floor which is dricor with electric heating wire on top, then tiles, and unfortunately it looks like some of the dricor wood got wet as well! We have industrial fans going 24/7 to try and dry out the room and also have a dehumidifier running, I’ve had the heated floor running in hopes that it could help dry any of the wet wood directly below. The humidity in the room is currently 40! 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
Do you think that heated floor actually help to dry or do they make things worse and more humid! Am i looking at mold if i dont rip the floor out?
Any ideas or help is greatly appreciated
Thank you
Hello
Enjoyed the article.
So if I understood the article right and not sure that I did. Being that we live in Central Florida, 40 miles North of Tampa and using this chart page 5 ( https://research.cnr.ncsu.edu/blogs/wpe/files/2016/08/Equilibrium-Moisture-Content-of-Exterior-Wood-in-the-US.pdf) were it states EMC for wood exposed outside for our area of 12.5 to 14.0 when I put the moisture meter to the wood it should be in those ranges if going to be used outside?
Damn those shop classes I didn’t take.
Thanks
Mark
Mark,
The EMC outside and the wood should be the same. For example, if you were to have an EMC of 14%, then you would measure the wood’s moisture content and make sure it’s at 14%. Some wood you buy from a lumber store can be higher than 14% but typically range between 12-14%. If you need further clarification http://www.nwfa.org is an excellent source. Hope that helps
A nice article. Thanks for sharing.
This article is really helpful. Very simple and understandable. Thank you.
Thanks for the the information, very detailed and useful. I may have missed this already but I have a few quick questions.
1. What are acceptable ranges of moisture for composite materials like MDF and Plywood, for indoor furniture use?
2. Will your meters work to find MC levels for composites?
Thanks!
Billy,
Yes, our moisture meters read MDF. The SG setting is on the card that comes with the meter. Hope this helps.
Hi Larry
we are getting hardwoods from our Uk Suppliers and accoya coming in at 2% and once we use the timber we are reading 0% we have tested the reader and its accurate even joinery grade sapele wood and Tulip wood coming in at 0% we cover these in 3 coats of sikkens paint and sometimes we get jobs where we are having to go back as our joinery is moving and we are guessing its because of these moisture levels and had never checked previously.
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. my question is, is there a possibility that the wood will shrink because of the weather condition?the wood that we used for the door frames and bidding is beechwood.
Hello Von Ryan,
When wood is subjected to an environment that is higher in humidity, it will swell or expand.
It is best to obtain a wood moisture content that will match the environment.
You can determine the correct percent moisture content by using our free app called “WoodH2O”.
Hello Larry,
Great info! I have some black walnut and cherry that I’ve milled and want to make some charcuterie, cheese, bread boards…etc with,
would the 6 – 8% dryness apply to this or what would you recommend?
Thanks,
Kim
Hi Kim,
Yes, hardwoods such as cherry and walnut should be between 6 and 8% moisture content.
Hello Folks,
I am new to wood turning and do not have a ready supply of dry/seasoned (my wood is green) wood. Having performed multiple (>500) soil moisture and density Sieve and Proctor, so I am well versed in moisture calculations (both add and subtract). My question is microwaving twice turned bowls what would be the general rule of thumb for a target by weight. ie… SW=Starting weight, TW=Target weight, using T%=Target percentage
My calculation ( T% X SW = TW). Please help with T%, I have seen where 30% moisture loss by weight is a good rule of thumb to shoot for. I do not have a hygrometer or a moisture meter as I am a hobbyist.
Chris
Hi Moisture Experts,
My house is 25 years old located in Oregon City OR (near Portland). New roof first week of November. Down pour of rain onto underlayment of attached garage. Observed water leaking along seams of several sheets of original plywood in attic. Had fans and dehumidifer running for 17 days starting 2 days after leak. We have had on/off rain and humidity 80-90% range. Drying equipment removed 3 days ago. We are checking moisture levels in several areas each day. Most are reading are between 13-15%. One sheet of plywood is 25% next to a 2X4 truss reading 17-27%. The next sheet is 21.5% adjacent to 2X4. We don’t know if we still should be having a commercial drying process? We don’t know if we still have leaks?
Any advice would be appreciated. Thanks!!!
Judy,
Hello and thanks for writing in. I would love to be able to give you the perfect answer but unfortunately, there isn’t one. Continue reading MC in the home. I have seen home built in the dead of winter, covered in snow, and still dry out enough for a successful home build.
hellow!
this is an interesting read I landed upon as I was searching for MC in wood items.
I buy many Artificial Trees for our Stores, which has Wood Stems/Barks, mainly produced in China & Shipped to UAE. could you please guide or on how much should be the Expected Humidity % in high Humid areas like UAE considering these are mostly for Indoor purpose where AC’s are on 24×7 at say 24 Degrees.
look forward to your comments.
thanks so much in advance.
I really appreciate your treatise on this matter.
1. in Indonesia there are a lot of raw materials consisting of natural fibers, such as: pandanus, water hyacinth, rattan etc. how do I determine the mc standard for this material, is it the same as wood or has its own specifications
2. The next question is almost the same as before, if we have various kinds of wood, such as March wood, mango wood, pine. Are the measurements of all wood the same? or finally the product will be placed where
3. If the wood is covered by a material like MDF or other, do we take 2x the measurements? wood using pins while the MDF uses pinless?
Thanks
I have a black walnut slabbed up that has been air drying outside for 2 yrs. Its mc is 11- 12% . i want to make a headboard from it. Do you think its to early to start working with it.If so how many yrs will it take to get to proper mc so i can work with it. Thanks
Todd,
Where are you located? If you want, just give me a call at 800-634-9961, ext 225.
Hello,
Thank you for the helpful article. I just bought a live edge slab of Cherry from a local sawmill that was kiln dried. I checked it with my new moisture meter and had a reading of between 8-13.5%. I want to use it to build a table and will be moving it to the location where I will work on it shortly. It will be there for a few months before I begin working on it. I have seen that 13.5% is high for furniture and you should aim below 12%. Do you agree with this? How long will it take to get to the ideal moisture reading and is it better to be stored in a garage or inside a house?
Thank you!
Riley,
Moisture content (MC) in raw slabs can take additional time to reach its Equilibrium Moisture Content. (EMC) than other pieces of wood, depending on its location.
Since wood is hygroscopic, it loses or gains moisture depending on the relative humidity of the surrounding air. Varying humidity levels can cause wood to lose or gain water and shrink or expand.
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. It is impossible for me to tell you what the percentage of furniture should be, but if you know the EMC in the area it will be kept, you can check the MC continuously until you reach its EMC. I hope this helps.
Hello, Paul here. Thank you for sharing such valuable information.
In March of this year I had new white oak 2” flooring installed.
The new wood was brought in in bundles ~2’ x 2’ x 6’ and left that way to acclimate for ~2 weeks.
They were installed over existing plywood subfloor. Room size, L-shaped, is 21.5’ x 12.5’ and leg of L is 8.5’ x 11’.
The floors have started cupping across the entire area with more in some parts.
With a Wagner L606, I am getting MC readings 12%->15.5% . Just across the threshold to a white oak floor installed in ~1914 and the MC is 15%->16%. The conversion puts the adjusted MC between 9.5 -> 12%. Does that seem normal. And would it be normal for the MC to vary from board-to-board and one end of a board to the other?
I am planning an under-house excursion tomorrow.
What would one expect to read in plywood subfloor and old growth pine floor joist?
I have a question, I have moisture in the crawl space, we insulated the crawl with closed cell, cannot get the osb subfloor below. 17 and the flooring is at 6 to 7. What can we do to get the row products closer in moisture content, we are currently using fans,
We are in northern lower Michigan
I am the general contractor for the house, and want to avoid any problems, would love to talk to you on the phone, my number is 9894647248, Mark Skiba
This is a great site about moisture content. Thanks.
I have a question. What humidity content should cedar be at for proper gluing.
The cedar I have is now at 12-16%. Should I wait?
Thanks
Phil
Phil, what are you making with the cedar, and in what type of environment will it be? Also, the glue manufacturer should ideally give you some specifications for max and min moisture content.
A contractor is measuring sill plates by driving 2″ SS Screws into the wood about 1-1/2 or so inches. Then placing his pin meter on the screws. Would the screws skew the measurements?
About 5/16 penetration into the wood measures 8% using pins only. But when you touch the pins to the embedded screws, you get between 14 and 24 % in various areas of the board.
I suspect the screws may be skewing the measurements. Any input would be most appreciated.
Not using the correct procedure. Longer pins with insulated shafts are designed for the purpose. If he is using a high-quality product from companies such as Delmhorst, they provide a slide hammer pin attachment, and they need to use insulated-shaft pins.
we had a problem with our shower curb. water leaked over the edge. the curb is built with 3 2/4’s stacked on each other. i did not waterproof the outside of the curb (kerdi), so the wood got wet. i used my dremel with a shaping bit about 1/8 in to cut vertical slits or vents about an inch deep and a couple of inches tall into the bottom 2×4 and have kept a commercial floor blower on the wood several hours a day for more than a week yet, the number is not going down. at one spot, it’s 40%. i also drilled into the wood every few inches, several inches deep with a typical drill bit.
i cored out a small section of the bottom beam (3 inches wide) all the way down to the foundation. the concrete was completely dry, no standing water. i am baffled. i don’t understand how the bottom beam looks like swiss cheese from all the holes i’ve drilled and has had a commercial blower on it for days yet the number is still high despite there being no visible water to keep the wood wet.
Dear Larry,
It was such a good read. Thank you for the well described article. I manufacture ice cream sticks and disposable wooden cutlery from European Baltic birch wood in India. I am presently drying it to around 8%-10% and then rotary polishing it, but I am facing the issue of burrs on the edges. If I dry too much, there’s discoloration and breakage of product during polishing. So what do you think is the ideal moisture% I should dry them to before rotary polishing them?
Which Orion moisture meter model would you suggest for my application?
Thank you
In wood products manufacturing, 6-8% is pretty much the norm, at least in North America. Too dry and you get chipping out of the wood. Too wet and you get fuzzing. So the question is ‘are those burrs or fuzzing on the edges?’
We’d love to have you give us a call to discuss which moisture meter is best for you. 800-634-9961, or email sales@wagnermeters.com
Hello! I’m trying to find specs on treated lumber for NC. We will be having a deck built off my woodshop. I requested the treated lumber be brought in a few weeks prior to build, stickered and put under cover to acclimate and dry it. Was told that’s not done. My last Wagner was appropriated by the individual who appropriated other tools out of my old sho. Two questions – I need a reliable, easy to use meter that can cover all species as I now have a portable mill and that can be used for treated. I had a pin meter but found I had to put the pins in the ends or try to find an area that wouldn’t be seen, so I’m thinking a pinless might be better. Accuaracy is of course more important.. Which do you recommend? The other question is what should the moisture content be on treated lumber that will be for the framing of the deck? When I purchase it it’s soaking wet and I’ve always given it a few weeks, stickered and covered for at least 2 weeks, sometimes up to a month, to get it down to around 17-19%. Have I been wrong?
Hug the ones you love when you see them!
Elaine
Hi Larry, thanks for the great knowledge sharing. I wanted to know if is there any standard which specifies the acceptable range of moisture content for wood used in packaging industry like pine wood. If you know such International or Amercan or any other standard please let me know.
Thabks & regards,
Amit Singh
India..
Hello Amit,
I am not aware of a standard moisture content for packaging food or any other product. I would think it would vary depending on the contents. Most types of wood species will mold above 25% moisture content, including pine.
Hi Larry,
Many thanks for your advice, really appreciate it!
I am based in The Netherlands. With the WoodH2O-app I could deduct the EMC for The Netherlands would be between 15 and 16. We also ship to other European countries, for dryer country like Spain the EMC could be between 12 and 14. If the wood would really arrive with a MC of 14%, we would not have any problems. That’s why I think the wood is either not dried to 14%, or it has picked up too much humidity after drying. In their warehouse, and perhaps partly also in the container.
The solution seems to be drying the wood longer & bettter, to a lower ‘measured’ MC. Or perhaps I should advise them to buy Wagner meters, for better accuracy ;-).
Hi Larry,
Brilliant article. Is it possible to get a 99.9% moisture reading (using a Cassain GM-200 hydrometer) on a particle board floor which looks and feels completely dry? The floor (under carpet) had long-term water exposure supposedly from a shower in the adjacent bathroom (according to the plumber). The plumber said that the floor has an elevated moisture reading and took a photo showing the 99.9% (maximum reading) on the meter while the meter was on the floor. There are water stains on the particle board floor, but the flooring felt completely dry a few minutes after the reading was taken (I didn’t see the reading being taken), the floor looks dry in the plumber’s 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. I would have thought that if the floor gave a 99.9% water saturation reading, it would have had to have been noticeably wet.
Your response is eagerly awaited.
Writing all the way from Australia, Steven
G’Day Steven,
Yes, it is possible to have a moisture content reading of 99.9%. It is also possible to have moisture content readings over 100%. This means the weight of the water exceeds the weight of the wood by itself.
While the surface of the floor might feel dry, there could be higher moisture inside. 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. It is best to replace the particle board subfloor.
Dear Larry,
We have started to import teak outdoor furniture from Indonesia into Europe. The containers that we have received so far have arrived wet and mouldy. The supplier says they dry the wood to an MC of 14%, which is according to them the standard for outdoor furniture. In your blog I read that furniture for outdoor is dried to a MC between 9 and 14%. That is still quite a wide range. Would you be able to say anything about the optimal MC range for this specific situation? Drying teak hardwood from a humid climate, for use outdoors in a much drier European climate?
Hi Erik,
Your English is excellent.
I’m not sure which part of Europe you are from, but typically the Indonesian climate is very humid compared to other parts of the world. It seems to me the supplier is drying the Teak to 14% because that is what is needed in Indonesia. You should be able to specify a lower moisture content. It is also possible high moisture has entered the container during the trip to Europe.
Wagner Meters has a couple of resources to help you determine the moisture content more suited to your outdoor environment. We have a free app called “WoodH2O” for Android or iPhone. This app will tell you the percent moisture content that a given temperature and humidity will equilibrate to. We also have an ‘Orion 950’ moisture meter that will automatically give you EMC (Equilibrium Moisture Content) and other useful statistics. Here is a link to our website for more information: https://www.wagnermeters.com/shop/orion-950-smart/
Hi there,
we are presently constructing a new timber frame residence on ocean front in BC, Canada. We will be building fir windows. Currently the RH is 76%, the residence RH will be set at around 35%. The fir windows and exterior doors will be affected by the the exterior and interior RH. What is the optimal MC of the fir stock for construction of the windows?
The fir stock was originally KD’d to around 8% but has been covered and stored outside for over a year and currently MC is around 12%.
Looking forward to hearing from you.
Brian,
The average annual relative humidity will play the biggest role in determining what the optimal MC should be. Here is a link to a calculator and table: http://www.csgnetwork.com/emctablecalc.html
Hi Larry,
This is all very helpful information, thanks! Question for the expert: i recently replaced a toilet that had a leaky wax ring. I’m on a grade-level concrete slab, and the water made its way over (under the tiles) to my sink vanity. The sink vanity is made from typical laminated particle board, and I’ve been trying to dry it in place using a dehumidifier and sealing the area off. I’m down to ~13-19% MC near floor level, based on a cheapo moisture meter’s readings. Is this dry enough that I’d be able to reinstall the trim over the particleboard? (It’d effectively seal the cavity under the vanity, so once the trim is back on, i don’t think it’ll dry out much more.) I’m in Milwaukee, wi if that matters.
Thanks in advance for your input!
Best,
Kyle
Kyle:
Thanks for the question. It’s hard to gauge anything off of a cheapo meter, but if and I mean if, we were to assume it was reading effectively, the numbers are too high. In your area, wood that has been in an environment to a duration of time would be between 6-11%. I hope that helps. Good luck.
Hello,
We are shipping some acacia chopping board to colorado ( US) with moisture ranges from 10-14% while shipping from India but once product received all get cracked . So please help us to know what should be required moisture level in Acacia board in final product if we need to restrict wood movement at Colorado .
Your help for resolving this issue would be highly appreciated .
Thanks,
Krishna
Hello Krishna,
Colorado is cold and dry. 10 – 14% moisture content is too high. A good moisture content is between 6 – 9% for Colorado.
Hi Larry, just finished a black Walnut dining room table back in November. There was a board that cracked along a glue line. The table had a 1 3/4 “ X 3 1/2 “thick boarder with mitred corners and biscuited. The interior was 3/4” BW the table’s dimensions were 40”x 70” . First time this has happened (splitting that is). I suspect the moisture was the culprit?
I have removed the 1 3/4” edge and resawn to take out the splinter (1/4”) re bicuited . I used my Wagner meter and it
Measured in the 10% area. I’m hoping this should work.
Finally the question I have is I-used your Wood H2O app and the humidity here (outside) is 55% and the temperature is near 70 (inside)am I correct that 10% is what Is the acceptable moisture of the wood should be for furniture building?
Cheers,
Howard Pruden in Edmonton, Alberta where it’s cold and dry😬
Hello Howard,
You mentioned the humidity outside is 55%. But the table will be inside?
Typical humidity levels inside a home is between 40 to 50%.
Typical moisture content for furniture in a home is 6-9%.
Your table may have been a little too high in moisture, hence the crack as it dried slightly in the drier environment.
Hello – I moved into my new home in June of 2018. We built our home from ground up and have a sealed crawl space dehumidifiers, etc… In January of 2019, we had our builder and hardwood floor contractor come out because our hardwoods were starting to separate a lot. We had boards that were also cracking/splitting and other places where small pinholes were showing up. I have about 3,000 sqft on my first floor and this was relatively consistent throughout.
My builder and flooring contractor asked for me to give the hardwoods a season to acclimate and they would surely move back together in june/july time frame. I live in Charlotte, NC. They said if i wanted to spend the money, a humidifier would help keep the humidity inside the house more consistent throughout the year. So, i had one installed a few weeks after we met.
I called them back out in August of 2019 because after installing a humidifier and in the prime of humid season, the floors were showing no signs of improvement.
They are now saying that they will replace whatever boards are bad and resand and finish the floors, however I’m concerned that there is an underlying issue that will resurface here? Looking back at pictures of the build process, they brought the hardwood bundles into my home in late October of 2017 and installed them 3 days later. At that point in time, we did not have a conditioned house.
We just had a hydrometer installed in the crawlspace and it is reading 38% as of today.
One note is that we did have some fungus growth in our crawlspace during the construction phase prior to the crawlspace being sealed and had the contractor come and spray and clean the floor joists and subflooring where applicable.
Any thoughts as to what the issue was with the first install so we don’t have the same issue again next year after we go through a new install?
Thanks for your help!
Jason,
My main concern here is that the flooring didn’t have enough time to acclimate to the surrounding conditions.
You mentioned it was installed just 3 days after it was delivered. Hardwood flooring needs to acclimate at least 2 weeks, in service conditions, before it is installed. It is important to have the same temperature and humidity during those 2 weeks that will be maintained after installation. The flooring pieces should be removed from the packaging to allow the ambient conditions to equalize the wood.
Prior to the flooring installation, make sure your subfloor has not experienced leaks or other water damage. A moisture meter will help verify. I recommend one of our Orion models:
https://www.wagnermeters.com/moisture-meters/
Working with some slabs of spruce. These are slabs roughly 2′ thick.
Cut in the spring and stacked and dried them over the summer. I know the rule of thumb is 1 year of dry time per inch of thickness of wood. Spruce isn’t a hardwood so I’m assuming I could get away with a shorter dry time. Currently reading a 12.5%. I have a couple questions. Since I’m drying them outside, being in AK I would like to work with them if possible before the long moist winter.
1. 12.5% is gettin there but not quite to the 6-9% mentioned in the article. Can I get a away with this?
2. I would like to rip two slabs and glue them together to make a nice large dining room table. Should I wait for the slabs to be within that 6-9% to cut and glue? Can I a cut them first, then glue them once they are dryer?
Hi Scott,
You are correct, furniture grade hardwood is typically dried between 6 to 9%.
Softwoods, such as spruce, can have more moisture. Your reading of 12.5% tells me it is workable.
You must be careful with a thick slab once you cut it. If the middle is wet, you may experience cracking/splitting if dried too fast. I would also consider the environment where the table will live. We have a free ‘App’ called WoodH2O that will tell you the moisture content given certain temperature and humidity conditions.
I had engineered hard wood installed and it is curling at the joints. I live on the fl coast so what should the moisture level be?
I really need to know as I am getting so many different opinions
Thanks
Barbara:
Thanks for the question. A general rule of thumb for the coastal regions of FL would be 11-13%MC. 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. Good luck.
Jason
I have an unusual question, if I was to sandwich recycled paper (similar to hardwood floor paper only heavier) between 2 layers of wood as a draft stop what should the moisture content be to avoid the paper absorbing any water and ending up with a mold issue thanks in advance for any info you can provide
Ewan:
Thanks for the question. From a strictly static MC%, 16-20% MC for long duration is going to promote mold growth. Obviously, the ambient conditions within which the wood or paper is present can alter the MC% of the wood or paper. So, when looking at the relative humidity of the space, spaces left above 70% RH for extended periods will also promote mold growth. Good luck.
hello I been getting very sick in my home so I had my manger do a mold and moisture test which came back high level of moisture levels which a contractor wants to take the sub floor up and 2 to 4 inches of the wall but my apartment manger is not releasing to report and he’s is saying the spore test didnt pick up any mold spore… question is it safe for me and my family to be in the home with high level of moisture in the restroom which the floor have been really soft for over 9 months now as well as the kids bedroom where a pipe burst
Hi Davetta, You’ll need to contact a local mold inspection company that is certified.
My question: what is the complete saturation reading of wood? WME?
Kevin,
Percent moisture content in wood is the ratio of the weight of water compared to the overall weight of a piece of wood. A 10% moisture content reading means that 10% of a wood sample’s weight is due to water in the wood. If a board reads 100% (Difficult to measure accurately) then the weight of the water equals the weight of that wood.
It is possible, in some species, to have a moisture content higher than 100 percent. This means a very absorbent wood can retain more water, weight wise, the weight of the wood itself.
Hi, in MN where extreme temperatures are very hard on homes.
What do you recommend the reader to be at before insulation and drywall on new construction?
We have had very bad cracking in sheetrock and floors.
Thank you
Rachel,
2×4 and 2×6 framing studs should measure 19% moisture content or less. This is the standard in the construction industry. Subfloor material such as plywood or OSB should measure between 10 and 14% moisture content.
Toilet overflowed and moisture meter is reading 30% in worst area. Can carpet be reinstalled?
Shirley,
Before installing carpet, you will need to dry the subfloor first.
If your subfloor is a wood product, make sure the reading is less than 20% on the moisture meter.
Also, if the leak was bad enough, it will be necessary to have a contractor make sure the strength of the subfloor isn’t compromised.
Hello Larry
I am from Bangladesh. Here current humidity is 76%. What would be the recommended MC for doors of my new building(under construction)?
Hello Tapon,
If the humidity is a constant 76% then the wood will equilibrate between 14 and 15% moisture content.
Hi Larry,
So a friend of mine has some pine and oak blabs at MC levels of (oak – 11.5%) and Pine 13-14%. Now would the pine be okay to use as a top cover piece to an radiator cover? if not, can you tell me why? Second, would the same pine slab, would it be okay to use for a side table or Kitchen island. I have come across this and haven’t made the purchase from my friend because I am not sure about the warp or breaking it will come.
Thanks
Hi Jeff,
As with any wood product, the environment where the finished product will “Live” will determine the correct moisture content. Moisture content of 11.5% for the oak is a little high for furniture grade hardwoods. Again, the correct moisture content will depend on the surrounding conditions. Wagner has a free app called “WoodH2O” to help you determine the proper moisture levels based on consistent humidity and temperature.
I dialed the 800 number for Wagner meters and all I got was two sales pitches for a Life alert type device. The other was for a $100 retail gift card. I wanted to talk to someone at Wagner about moisture guages and is there a dealer near Chattanooga, TN.
Hi Jim,
Oh no! We’re so sorry for the inconvenience. Please give us a call at (800) 634-9961 or email info@wagnermeters.com, if you’d prefer. Also, please feel free to provide us with the number that you called so we can make sure that all of our phone numbers are printed/posted accurately!
Thank you,
Hi Larry,
We’re looking to replace the floor in an old (unheated) hay barn with treated tongue & Groove 2×6 flooring and need to know if the advertised 19% MC will be ok and not shrink too much. We’re in northern Indiana, humid summers long cold winters…
Thank you for your help and any advice!
Tom
Treated wood is typically still wet when it’s delivered to the job site. As it dries, you should expect slight changes in width and length. As lumber dries, it may split, cup and warp. This is more likely to occur to occur in lower-grade boards, where knots and uneven grains are already present. Each piece of lumber is unique and carries physical characteristics that may include the following: knots, warping, shrinkage, swelling and/or splitting.
The normal outside equilibration moisture content (EMC) for Indiana is anywhere from 13% to 16%. There will most likely be some shrinkage, so if possible, choose the clearest boards possible to lessen the possibility of any major cracking.
Thank you for your very informative knowledge about all of the items on this page. This summer I milled several 1.25″ boards from a fir log that had been cut around 10 years ago. Moisture was around 25% when milled, and the ends were sealed. The boards have dried nicely so far with minimal warpage or checking. They are currently nearing equilibrium (around 12 MC) and are stored within the house. My plan is to make a wall-mounted headboard out of angle iron and these boards (boards will not be joined). My question is regarding finishing. I have used spar urethane as a finish on a few other 12 to 18 MC (semi-wet) log projects that turned out wonderfully. However, this time I was planning to use oil based poly rather than the spar urethane to reduce the amount of yellowing. One of the beauties of spar is that it allows the wood to move quite a bit, while still retaining good adhesion. Do you see any dangers of using poly with a MC of around 12, or am I risking adhesion failure – especially if the wood does end up shrinking dimensionally? The angle iron will prevent much warping, and I do plan on finishing all sides (and ends). Thank you so much for your time and expertise.
The manufacturer of the oil-based poly should have a specification on the maximum allowable moisture content of the wood. Question: Just to make sure that you get accurate moisture measurements, has your moisture meter been checked for calibration?
Larry,
I found your moisture levels column through a search for “good wood for low humidity”. I think that I know my own answer, but thought I might reach out for some possible better insight. I have built two table tops (douglas fir) that have both suffered major cracking in their final location. I built the tables in west Texas, but their final home is in Colorado. Both times, the tables were flawless, but after 2-3 weeks in their new home both table tops had major crack issues. We found out that RH at the final location was under 20%. RH where they were built is about 29-30%. 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 going…but that doesn’t seem to be the case. Allowing the wood to acclimate in the final spot before building, really isn’t possible because it is 8 hours away, and I can’t take a week off to go up there and build the table. Any suggestions to this being possible to correct? Different wood? Different joinery (currently using pocket holes)?
Thank you for your time.
Brian
Hello Brian, I am a moisture meter expert, not a woodworking expert but from your description, the problem points to the conditions, not the wood or joinery. Wood is a hygroscopic material, meaning it picks up or loses moisture based on the ambient conditions. There is only so much moisture a piece of wood can give up, over time, before a failure occurs. The failure in your case sounds as though the piece was exposed to a rapid loss of already low ambient moisture, causing the cracking in the piece.
The optimal humidity in a home is generally 35%-55% and anything under 20% is actually considered unhealthy, as it dries out the skin. It does the same for wood, and is especially hard on softwoods, such as pine or fir. It is not uncommon for wood to expand or contract as much as a 1/8” per foot of width, so maintaining a stable environment is important. If the conditions are too wet, dehumidify, and if they are too dry, humidify.
I strongly recommend using a moisture meter, along with a thermo-hygrometer, or even a smart logger before you start building, to ensure the wood is at an optimal moisture content in an environment that has an acceptable relative humidity and temperature range. These tools will give you the confidence that you have done everything on your part to ensure the highest quality in the piece you have built.
Here is a link to our moisture meters, thermo-hygrometer, and Smart Logger.
https://www.wagnermeters.com/wood-moisture-meters/
I have 1 1/2 ” thick cherry boards that I had milled from a tree in my yard last fall.
They are in an unheated and currently very cold barn
The moisture ranges from 11% -16% according to my meter.
What % does it have to get down to before it would be usable to make a table top ?
Thanks
Jim
Jim,
Furniture grade wood is typically dried to a target of 6%-9%.
Hi Larry,
Thanks for the reply. There are joists that display splitting. We haven’t gone any further since the condition was found so close to us purchasing the home. So we are seeking redress, but there are jacks present underneath the home which the home inspector didn’t report either and didn’t know if this was extra support for the water heater or what. There are areas where organic growth was very active to cause deep, black discolorization. I will get further testing from those not involved. Thank you.
Hello Larry,
We just bought a home where we discovered the plumbing was leaking over a number years with a kitchen flood occurring in the last 3-5 years due to a busted water line. The water wasn’t properly dried and organic growth was discovered by previous owner. Instead of addressing the plumbing and damaged wood, they installed a dehumidifier in 2015. 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. A company sealed off the foundation vents and removed all the insulation from the crawlspace with the humidifier mitigating the moisture from the leaks. Since the cold weather has come on, the organic growth has gone dormant, but a contractor noticed joists with distinctive moisture content where there are definitive separations between dry and wet looking wood. However, the company who maintains the dehumidifier said he tested some of the joist which he said only registered 10 on his device. I don’t know what to believe except the company who installed the vapor and dehumidifier said the vapor barrier needs to be changed out because of all the sewage and drainage stains after the plumbing is fixed. One of his own service guys said foundation caps needed to be replaced. Wonder if they are trying to cover themselves. Live in Tn. The plumbing was improperly installed with the wrong cement to fit the pipes and could have been leaking from anywhere between 5-29 years while absorbing into the ground. Any opinions.
John,
If the water leak was bad enough, dry rot can occur causing possible structural integrity issues. Did the Contractor mention anything about the structural strength of the joists?
One of our new line of moisture meters will help locate areas of high moisture, if it still exists. Mold starts growing if the moisture contents reaches about 25% moisture content. Here is a link to our new line of meters:
https://www.wagnermeters.com/moisture-meters/
Larry,
I am building a farm style dining table with pecan 2″ thick X 8′-0″ long boards.
The lumber was recently milled, although the tree had been cut months, years ago.
What should be the approximate Highest MC to prevent wood problems to include finishes?
Thank you in advance for your response.
Humberto from Texas
Humberto,
The typical moisture content for hardwoods that will be indoors is 6-9 percent. You will want closer to 6% in the drier climates and 9% MC for the more humid climates. Either one should be acceptable for finishes. It’s always a good idea to check with the manufacturer of the finish also.
If a wooden sample has moisture content range of 2-6% only and if it has moisture content of 9 or 10% then what does this mean??
Mobeen, If a wooden sample gains moisture, then the sample will increase in size. This can be a problem once installed in furniture or a floor. It is best to allow the wood to equilibrate to the room environment.
Should you check moisture levels on a trailor floor on a massive rainy day? Will the reading be accurate?
Dana,
Any time water can be absorbed into a material such as wood, drywall etc, it’s always a good idea to check for excessive moisture, especially if you suspect a leak. Other than causing structural damage, too much water can result in mold growth.
Here is a link to a moisture meter I recommend: https://www.wagnermeters.com/shop/orion-910-deep/
Hello,
I am renovating my kitchen and installing hardwood floors. The floor installer put the floors down without allowing the boards to acclimate. When questioned, he said because Room is under 200 sq feet it is not a problem. Is this accurate?
Christian,
That doesn’t make much sense to me. The purpose of acclimating is to allow the flooring to equalize to the surrounding conditions, no matter how large the room is. Be on the lookout for flooring failures such as swelling, buckling, cupping, etc.
If any of these conditions occur, tell your installer right away.
I had a water leak under my crawl space which has 3 inches of foam insulation applied to the underside of the sub floor. The water eventually came out a electric outlet located three inches off the floor. I removed an of the foam insulation. The subfloor registered from 12% to 17% . Should I remove more foam to be sure. The engineered wood floor appears ok. I live in coastal South Carolina .we are definitely afraid of mold formation. Any suggestions .thanks
Eric,
Is your electrical outlet that is 3 inches above the floor inside the house? Water was coming out of this outlet and onto the floor? If that is the case you need to remove the flooring and examine the subfloor. You should be able to tell where the water reached the subfloor because it will be discolored and may also be swelled up.
Moisture contents of 12 to 17% is ok. You don’t want to see any subfloor reach about 25% which is where mold will start to grow.
My house is 24 years old. 18 years ago the moist content (MC) of the beams and joist was 24% in an area of the crawl space that floods in spring. I installed a sump pump and 6 mil vapor barrier, but the barrier is not sealed around piers and the ground is moist under the barrier all year. I was able to get the MC down to 15%. I also applied Boracare (boron) that has stopped minor beetle damage.
Three years ago, the floor sank in a heavy traffic area and an engineer told me Masonite was used to shim and had compressed. Over a year ago, I re-shim all the piers with metal shims. The floor immediately felt stronger.
Prior to the re-shim, the pier in the area that floods in the spring could be felt pushing up the floor, meaning the beam is warping and been monitoring it. This week, I notice the next pier on the same beam is starting to push up, warping the floor. Knowing were all the piers are, I can stand on top and feel a small hump in the floors. You can hardly see the humps except the first pier that popped up ¼”.
I had a quick looked around the crawl space and didn’t notice any structure damage. I not sure if this is normal, related to the re-shim or need to install a crawl space dehumidifier to slow the progression?
Thank You.
John,
A dehumidifier in the crawlspace will help but can be expensive. The purpose of the vapor barrier is to keep moisture away from materials that expand and contract. Perhaps try to seal the vapor barrier better around the piers.
The other thing to consider is examining how water is entering your crawl space. Perhaps better drainage around your house will do the trick… or treat. Sorry, that time of year.
David,
I am having a section of our 3.25″ Maple hardwood floor replaced. About how long do you think we should allow the new wood to acclimate in the end use environment before installing it?
John,
Typically, allow about 3 weeks for hardwood to acclimate in the environment. Two weeks is sufficient for softwood.
It is also a good idea to use a moisture meter after the three weeks just to make sure. Here is the one I would recommend:
https://www.wagnermeters.com/shop/mmc220-extended-range-moisture-meter/
Hi Larry,
My potential house in North Carolina Fayetteville area was just checked for moisture content in the crawl space. The levels were between 20 and 23%. The house was not in the flood area however they did receive 20 inches of rain.
Do these levels seen appropriate considering the recent rainfall.
Thank you
David,
As long as the moisture content does not exceed those readings you should be ok. Mold starts to grow in the mid to high 20 percent moisture contents.
How to test moisture /water content in cassia bark? What is the acceptable water/moisture content in cassia bark?- in south east asia
Larry: I recently had my annual termite inspection. The inspector said his meter reading taken from my basement on subflooring/joists/framing was too high. (He didn’t cite a figure.) He added that plastic sheet ground covering that his company laid over my crawl space had been moved in spots and that I no longer had full coverage. I live in upstate South Carolina. We have had an abnormally wet spring and part of summer. I suggested replacing my dehumidifier (Sears brand, bucket collection) which has been inoperable this past year. He, of course, said that type of product is insufficient. He wants to install his company’s system, seal all external openings around connections, etc. for a mere $4900. My house was built in 1927. I get some water seepage through an exterior wall at basement floor level as a result of heavy rain. It is a 2-3 feet wide wet area that drains to a line connected to the city system. Generally the entire floor is dry. The air vents stay closed year round. What do you recommend?
Jerry, From a moisture standpoint, water in the basement can over time absorb into your subfloor. I don’t know what type of floor you have, but if it gets wet enough, about 25% moisture content or higher, mold can grow. Doesn’t sound like this has been a problem in the past. I would think at least fixing your dehumidifier is a must.
Hi, we live in a coastal area, had a recent water leak, and a hard wood floor MC is measuring about 25% – the water did not contact this area directly.
in other hardwood areas that wasn’t close to the water, was measuring about 16-19%.
our question is do we need to replace the floor to avoid fungal problems?
Thanks!
Hi Kevin,
A moisture content reading of 25% is borderline to support mold. You should be ok as long as the moisture content does not get worse (higher). Keep monitoring it.
Here is a good source for mold and wood:
https://www.google.com/search?source=hp&ei=j6WRW76_NdmT0PEPkN29kAc&q=wood+moisture+content+and+mold&oq=moisture+content+and+mold&gs_l=psy-ab.1.0.0i22i30l3.8963.15970..20676…0.0..0.100.1475.25j1……0….1..gws-wiz…..0..0j0i131.PkfEQYRef9I
Hi Larry,
We are manufacturer of eng wood flooring. My first question is how to determine the MC of eng wood flooring which composite of different species layer, face and different species to form plywood core.
Example: 1.2mm Hickory wear layer
9mm thick plywood compose of 7 layers, 2 layers acacia, 4 layers of Eucalyptus\2 layers Acacia and one layer Poplar.
In this case, what Built in # that I can use to measure flooring.
2nd question, will lacquer on surface of flooring affect the reading.
Samuel
Many of our customers are successfully using our hand held moisture meters on engineered flooring. The thinner veneers won’t have much bearing on the reading. Set the meter to the species that makes up the bulk, in this case, the plywood. The plywood setting is .57. Lacquer will not make a reading difference as long as there are no metallic components in the lacquer itself.
Larry,
I so appreciate your treatise on this issue.
My question for you is: after a smallish unheated underground space (similar to a basement, i.e. all concrete) is framed and sheetrocked (though not mudded or sealed in any way) is then the studs are tested for humidity, what would be a reasonable level here in Seattle, living approximately 100 yards Puget Sound? This building was constructed around 1966 and this little space appears very dry, in spite of a recent leak from an nearby hot water tank. The company they hired measured 47% in the ‘wood’ and declares that this must be ripped out and replaced.
Sorry that this is so long-winded and I thank you in advance if you are willing to address this question for me.
Thank you,
Renee
Hi Renee,
Standard construction studs such as 2×4 and 2×6’s are typically dried to 19% moisture content before they are installed. Any moisture content measured higher than that might result in movement, such as warping and twisting, once it dries. Also, there is a risk of mold. A wood moisture content of 47% is too high.