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Understanding Moisture Content and Wood Movement

(with Gene Wengert, The Wood Doctor.)

Expected movement can be accurately predicted, which means avoiding potential problems down the road.

In this article, we’ll explain the importance of understanding wood movement, how to use a moisture meter to measure the moisture content (MC) of trim, how to decide when a load of trim should be rejected, and how to accurately estimate how much trim will move after it’s installed.

Most finish carpenters are aware that seasonal changes in humidity cause trim and flooring to shrink in the winter and expand in the summer. But few realize that the expected movement can be accurately predicted and potential problems avoided. It’s our premise that with a moisture meter and an understanding of wood movement, most wood movement problems can be avoided. Plus, with this data, finish carpenters can accurately predict how trim and flooring will behave after it’s installed.

Wood Movement — You Can’t Stop It

Wood is hygroscopic, which means its MC will fluctuate based on the relative humidity (RH) of the surrounding air. As humidity increases, the MC increases, and the wood expands, and as the humidity decreases, MC decreases, and the wood shrinks. This relationship is referred to as Equilibrium Moisture Content (EMC), and can be accurately predicted.

Understanding Equilibrium Moisture Content

The moisture content of wood is tied directly to the relative humidity of the surrounding air. The higher the relative humidity, the higher the MC of the wood. Period. If you’re installing wood that’s recently been transported, or installed on a job, it might take a little while for the material to reach its equilibrium moisture content (EMC) with the air—in other words, for the wood to accommodate to the humidity level for the climate around the wood: the wood may take on more moisture or it may dry out. For example, if wood at 10% MC is exposed to 25% RH, the wood will dry to 5% MC (and shrink as it dries).

The EMC helps us understand the response wood will have to relative humidity, whether it will shrink or expand. For woodworkers and carpenters, the EMC is more helpful than RH. The simplified chart to the right shows the EMC values of wood when stored at the humidity and temperatures indicated.

Complete EMC levels for wood stored in unheated structures in your area of the country can be found HERE.

How Wood Moves

If the MC of the wood you install is too high, excessive shrinkage may occur, along with the risk of problems of unacceptable gaps and cracks in the wood itself. When the MC is too low, the wood may expand, and may buckle, bow, and distort surrounding material.

There are six key areas finish carpenters should be aware of when it comes to wood movement.

1. Width of material

The wider the board, the more movement will occur (the term “board” technically refers to wood 1 1/2 in. thick or less, but for this article its use will refer to wood typically used by finish carpenters). It’s a direct proportion: an 8-in. board will move twice as much as a 4-in. board, and a 12-in. board will move 3 times the amount as a 4-in. board. And it’s important to keep in mind that a glued-up panel behaves basically as one wide piece of lumber.

 

2. Grain orientation matters

Boards are characterized as being either “flat sawn” or “quarter sawn.” Quarter sawn lumber (also referred to as “rift sawn” or “vertical grain”) shrinks and expands roughly half as much as flat sawn. Most over-the-counter finish material is flat sawn, and you should assume flat sawn values unless you’re sure your material is quarter sawn. Quarter sawn lumber has annular rings that are oriented between 45 and 90 degrees to the board’s face. Flat sawn grain orientation falls between 0 and 45 degrees to the board’s face.

Wood Grain (Note: Click any image to enlarge. Hit "back" button to return to article")

3. Moisture content of the wood at delivery

The only way to accurately predict wood movement is to know the MC of the material when you receive it. Moisture content is measured using a moisture meter. Failure to check your delivered material means you have no chance of anticipating movement problems. Furthermore, material that measures outside of the acceptable MC level should be rejected.

4. Humidity inside and outside the structure

Homes in most of the U.S. that lack humidity control typically experience interior levels of humidity from 25% RH to 65% RH. This range of humidity will cause a 6% change in the MC of the wood. This change in MC will cause a 12-in. wide maple board to change 1/4 in.

When material is installed that was delivered at an unacceptable MC, or the humidity range in the structure exceeds typical values, the amount of wood movement increases—and can cause problems even in well-designed trim details. It’s worth noting that panel material (plywood, MDF, composite materials) move at about 1/10th the rate of solid wood.

In most of North America, exterior humidity levels range from 60% RH to 70% RH in summer and winter, but are lower in the Southwest, and higher near large bodies of water. If the material is delivered at 6 to 8% MC, it can experience more than a 2% change in size as it adjusts to the EMC.

5. Species affects the amount of movement

Wood movement depends in part on the species. A 12-in. wide western red cedar board will fluctuate 1/8 in. while the same size maple board will fluctuate 1/4 in. The formula for calculating wood movement is complex and extremely accurate, but tedious.

One simple rule of thumb serves as an approximate guide to predicting wood movement: “Most species of flat grain material will change size 1% for every 4% change in MC.” Applying this formula to a situation where the seasonal EMC ranges from 6% to 10%, a 12-in. wide board will change dimension 1/8 in.

I’ve put together a rough chart (see below, click to enlarge) that offers approximate movement values for various widths and commonly used species of wood. These values are based on flat sawn lumber, and offer a general idea of anticipated annual in-service movement. The movement values for quarter sawn lumber are approximately 1/2 the flat sawn values.

If you want to know exactly how much the material you’re using is going to shrink or expand, use this online shrinkage calculator. Simply enter the high and low MC values and the width and species of the board.

6. Applied finish does not stop movement

While it’s true a high quality finish will slow the rate of moisture exchange, it will not stop it. Material finished on all surfaces will expand or contract at a slower rate than raw wood, but make no mistake—finished wood will eventually acclimate to EMC levels.

Events That Increase Movement Risks

There are many events that can contribute to excessive wood movement issues. Nearly all of them can be prevented before they cause a problem if—and only if—you measure the MC of the wood as soon as it’s delivered, and avoid using wood that is too wet or too dry for the expected in-use EMC. The moment the wood is delivered, it begins to acclimate to the surrounding environment. At the very least, it’s important that you document the delivered MC, just in case wood movement becomes an issue. But responsible carpentry can’t be accomplished without reading the delivered moisture content of the wood and planning for wood movement during and after acclimation.

Excessive MC in delivered material

Optimum MC for interior millwork is 6-8%. In the real world, your material may arrive around 9-10%. For installations in unheated areas, the preferred readings are in the 12-14% range, assuming an area is protected from the weather. In most cases, you can deal with material that’s a couple of points high, but keep in mind that the wider the stock, the greater the movement. Ideally, the moisture content of wood should not change more than 2% when put into use.

Think through your trim details and consider how they will react when the wider assemblies shrink. With wide glued-up material, slightly higher MC levels may not be acceptable. If you’ll be installing wide material, it’s a good idea to be upfront with your supplier and let them know that the material’s MC must be within the range you specify. As a last resort, you may choose to dry the wood in your shop if the shop’s EMC is low, and have any shrinkage problems show up before the wood is installed.

Delivered material that’s too dry

This is seldom an issue for interior trim, but can be a real issue for exterior trim. Material delivered at 6% MC, and installed outside, will acclimate at 12% in the more humid months, resulting in a 6 point MC change. This swelling of the material can cause significant problems in situations where installation creates accumulated movement (more on this below).

Long-term storage of trim material

If you plan on storing trim material for any length of time in an unheated area, keep in mind that, in most parts of the US, the material will acclimate to roughly 11-12% MC. (See the humidity moisture content chart at the beginning of this article.)

If MC is too high, lower readings can be achieved by moving the material into a heated area. The amount will depend on the temperature and humidity of the storage area. The change in MC won’t happen immediately, and the material in the center of a pile will change at a slower rate than the material at the edges. Spacing the material so all surfaces are exposed to the air helps, as does good air circulation throughout the pile. You’ll need to take sample readings with your moisture meter to determine when the material reaches your intended MC.

Higher temperatures result in a more rapid change in MC when the humidity remains constant (roughly speaking, moisture moves twice as quickly for every increase in temperature of 20 degrees). And despite what you may think, moisture gain or loss does not stop when temperatures fall below freezing. The moisture in wood is chemically bound in the walls of the wood cells and cannot freeze.

Typical on-site humidity

At certain points during construction, such as when pouring concrete, plastering or drywalling, tremendous amounts of moisture are often added to the air, causing humidity spikes as high as 80-85% RH. If you are storing finish material on-site during these periods, be sure to keep them wrapped in a vapor impermeable material (like plastic) with as few gaps as possible. Wood stored in this manner will not pick up any appreciable moisture.

Interior trim should not be installed until the temporary construction humidity has subsided. Use an accurate digital hygrometer to measure RH (under $40). Generally speaking, interior trim should not be installed when the humidity is above 60%, or the material may climb above acceptable MC levels.

Humidity in un-heated areas fluctuates about 10%; therefore dry material (6% to 8% MC) installed in un-heated areas will swell significantly. It’s important that the MC of exterior trim be within 2-3 points of the EMC values for the area before it is installed.

In-service low humidity issues

In heating climates, older, drafty homes may see humidity drop, measuring 20% RH in the winter. The EMC in this environment will vary nearly 8% wintertime to summertime. Homes with wood stoves and no humidity control can see EMC swings of up to 11%. In extreme environments, consider using cabinet grade plywood for wide panel application instead of solid wood.

In-service high humidity issues

Typically, high humidity (constant levels above 60%) is not an issue. But if you find yourself working on a project that includes a room with a spa, heated pool, or damp crawl space, proceed with serious caution—85% RH means an 18% EMC. A 12-in. wide piece of birch installed at 8% MC in such a room will swell in width over 3/8 in. Letting your material acclimate to the high MC levels before installing is one approach, but keep in mind that if there is ever a period where the pool is drained for a significant time, and the humidity drops to typical levels, the trim material will experience severe shrinkage. A carefully-worded disclaimer regarding wood movement would seem to be in order.

Understanding Accumulated Wood Movement

Glued-up solid wood panels behave as though they were one wide board—a 24-in. wide panel will shrink and swell four times as much as a 6-in. board. But what about a series of boards installed side by side (T&G flooring, for example)? While it’s true that each board can move independently, accumulated movement can cause significant problems, typically when the newly installed material gains moisture. (See photo, right)

If the material in non-glued assemblies (flooring, for example) is installed “tight”, and there’s no gap to absorb expansion as the material gains moisture, the increase in width of each floor board becomes cumulative, and causes the entire floor to “grow” buy the sum of each piece’s individual movement. In cases of excessive shrinkage, unacceptable gaps can result between each floorboard.

For example, random width oak flooring is delivered at 8% MC. The width of the room is 12 feet, and the floor acclimates to a high level of 11% MC, the cumulative movement is about 1 3/8 in. In the real world, a lot of this expansion is “lost” as the fit tightens up, but in some cases the wood fibers compress, and fiber compression can cause grain ridges. By using a moisture meter, and predicting the movement, you can decide whether you should install the material “tight” or “loose” to absorb what you know will be an increase in material width.

Moisture content on exterior trim can range from 12% to 16% depending on the region, time of year, and location of the material. (Click images to enlarge)

Common Movement Issues

Paneled Passage Doors

Experienced door hangers know that a paneled passage door with a tight reveal will shrink in the winter and possibly stick in the summer. (Remember, if you live in California, the winters may be more humid than the summers!). But basing your door gap on the time of year you hang the door can be a mistake if you don’t know the MC of the door.

The seasonal width changes of a door are controlled by the MC change in the door’s stiles.

. . . . . . . . . .

If that fir door you’re getting ready to hang in the winter has been stored for six months in an unheated building, the moisture of the 5-in. stiles may easily measure 12-13% MC. After that door is hung, the MC of those stiles will drop to 6%, and the door can easily shrink 3/16 in. Knowing the MC at the time of installation provides the needed guidance.

And keep in mind that the door panels in this example will shrink significantly after installation. This won’t affect the fit of the door, but if the door finish is applied at the MC noted, there will likely be unfinished wood exposed as the door panels shrink to their in-service width. (See photo, left) This is particularly noticeable when a light wood is stained dark.

By measuring the MC of the door stiles, you can base your door gap on established movement values, not guesswork, and avoid callbacks when the fit becomes a problem.

Doors with horizontal battens

Unless you’re setup to build these doors properly, avoid them. The typical horizontal batten door is built using T&G material for the door face, and then battens are fastened to the back of the door to hold things in place. As the seasonal MC of the T&G material rises and falls, the boards expand and contract, but the battens—with their grain running in the opposite direction—resist that movement, forcing the door to cup inward or outward depending on the direction of the movement.

The detail below is one method used for cabinet batten doors that successfully allows for seasonal wood movement.

Captive panels

Resist the temptation to “picture frame” a solid wood panel—the way some woodworkers new to the craft miter a nosing or a frame around a tabletop. The miter joint will always fail when the panel expands and contracts. Instead, use a breadboard nosing design so that the wide panel can shrink or swell without destroying the surrounding joinery. (See below)

Inside corner trim

When installing trim that covers an inside corner, fasten the trim through the corner and into the substrate so the adjoining finish material can move independently as its MC changes. A typical example is base shoe molding. The best practice is to nail base shoe to the plate, with a long nail that doesn’t penetrate the baseboard or the flooring. But that’s not practical on most jobs.

The second choice is to fasten the baseshoe to the baseboard. Yes, the baseboard will lift off the floor in the heating season, but rarely more than 1/16 in. A wide floor, on the other hand, moves more than a 6-in. piece of baseboard; if you nail the base shoe to the floor, the base shoe may separate significantly from the baseboard.

. . . . . . . . . .

Common Myths

Wood is stable at below freezing temperatures.

The moisture in wood is chemically bound in the walls of the wood cells and cannot freeze, and expansion and contraction continues at below freezing temperatures. Wood does acclimate more slowly at lower temperatures.

Wood will expand on warmer days and contract on colder days.

For all practical purposes, thermal expansion and contraction of wood is not an issue. That said, warmer temperatures speed the exchange of moisture within the wood. Moisture exchange will happen more rapidly at warmer temperatures, but there is no thermal movement of wood worth measuring.

It doesn’t matter if lumber is kiln-dried.

Kiln-dried hardwood lumber typically leaves the kiln near 6% MC (softwoods at 10-12%). But all kiln-dried material will acclimate to the surrounding EMC levels. The significant advantages of kiln-dried material is that it is typically heated to at least 130 degrees in the kiln, which will stop any insect activity, and also “set” the sap in resinous softwoods (sap in resinous air dried material can bleed from the board after it’s installed, especially when interior temperatures rise in the summer).

They don’t make wood like they used to.

It’s true that most of the old growth timber is gone, but properly dried vertical grain material has highly desirable movement characteristics. If you’re seeking material that will move the least, choose one of the more stable species, and specify vertical grain (and be sure to check your wallet before ordering!).

But most importantly, owning and using a moisture meter and knowing the in-use EMCs is an inexpensive way for carpenters to predict and avoid wood movement problems that could require costly repairs.

———

AUTHOR BIOS

Carl Hagstrom is a partner in Woodweb, the leading online resource for professional woodworking. He has an extensive background in residential construction and architectural woodworking. He is also a contributing editor at the Journal of Light Construction, and a Certified Professional Building Designer.

Gene Wengert—having taken an interest in woodworking since 7th grade shop classes—was employed by the US Forest Products Lab as a college student starting in 1961. He worked in solar lumber drying, as well as discoloration of wood due to UV light. He then worked on the weathering of wood with the Lab and received a BS degree in meteorology from the University of Wisconsin. He continued to work on moisture related issues and developed expertise in processing northern and Rocky Mountain aspen, going from environmental benefits of the species through sawing, drying, and marketing. (Aspen is splinterless, did you know?) He worked at Virginia Tech as a wood specialist for the extension service, consulting with the wood industry daily. He also managed Tech’s sawmill and dry kiln.

For fun, Gene has taken up long-distance bicycle riding (at age 55) and has done two trips from the Pacific to Atlantic Ocean and three from the Gulf to Minneapolis.

Dr. Gene Wengert is Professor Emeritus in Wood Processing, Department of Forestry, at the University of Wisconsin (Madison). He is also a technical advisor at Woodwebs’s Sawing and Drying Forum, and Commercial Kiln Drying Forum. He frequently contributes to trade journals serving the primary lumber processing industry, and is president of The Wood Doctor’s Rx, LLC, through which he provides educational and consulting services to lumber processing firms.

Comments/Discussion

24 Responses to “Understanding Moisture Content and Wood Movement”

  1. Mike Pelletier

    Good article, I have not seen the panel kerfing detail before, interesting. Looks a bit fragile to handle during assembly, but interesting none the less.

    On the freezing topic: When you say “water” in wood does not freeze I assume you are referring to bound water not free water. If that is the case, are all species the same across the board when comparing their capacities to hold bound water?

    For example, if you were to dry three different species of wood from “green” to say 15%MC, would each of them be free of “free” water when they got to say 17%, then as the drying process proceeded we would be talking about reducing water bound in the cellular structure of the board.

    Or, would it occur at different levels depending on the capacity of each specie to hold free water?

    Reply
  2. Utah stair builder

    This is a great article. One issue I have seen is that when a house is built very fast the concrete will put a lot of moisture in the air. This will cause the wood work to swell after it is installed. It takes concrete a month to release all the water out of it.

    Reply
  3. jed dixon

    Good article Carl!
    A couple of comments:
    What you call edgegrain or VG (vertical grain) lumber is usually called and sold as quartersawn, at least in hardwood. There is no question that it is much more stable than plainsawn (what you cal flatgrain or tangential.)

    In my area, for at least 150 years in high end work, flooring is installed against baseboard without shoe molding. The base is installed first, and the flooring is installed scribed tight to it. In spite of what your lazy or ignorant flooring guy says, there is no gap, even after years of fluctuating humidity, and repeated sanding or scraping. This is because where the end grain of the flooring hits the wall, movement of the flooring is essentially zero with the grain, and where the edges of the flooring hit the wall there 1/16″ or less expansion (in 2-1/4″ oak t+g), because the flooring is fastened to the subfloor, and each piece expands and contacts by itself- not the whole floor as a unit. I’ve only seen unacceptable gaps between the boards when the flooring has been very poorly dried, or allowed to get wet before installation, and the only time I’ve seen a floor buckle from expansion is when there has been a major leak or flood, or when the flooring was installed over really green concrete.

    Reply
  4. David

    We are located in the Valley of the sun. we have two furniture factories here and often ship to moist environments such as the ocean. There fore we are shipping furniture from an arrid environment to a moist one. The particular job I have a question about will be shipped from our factory in phoenix to Sedona, AZ. We are building a number of pieces out of solid woods and wondering if maple moves less than poplar or alder wood. Which do you recommend at 5″ board widths by 2.25″ thick?

    Thank You,
    Dave

    Reply
  5. Roger Hollenbeck

    Good article about shrinkage on newly stained and installed
    panel doors and what happens when you don’t check the MC.
    As a home inspector on sometimes new properties some clients ask why the staining wasn’t completed. Now we know.

    Reply
  6. Michelle

    I am currently drying out my house due to water damage. Is it possible that wood can be over dried? If wood is already installed (no worry about it expanding), can the MC go down to 0% without any risks? Will a MC of 0% put the wood at more risk for fire?

    Reply
  7. Brian Todd

    was wanting to know what you recommend for a moisture content of a solid alder wood cabinet door should be when installed in Colorado Rockies at 11,000ft

    I am assuming 8-9 percent will this be ok?

    Reply
  8. Carl

    Brian …

    Without looking at the map, I would imagine your
    area is a bit drier overall then the average US.

    8-9 percent, in my opinion, is a bit high …. given
    that you’re in a potentially drier part of the county,
    I’d be looking at trying to achieve 6 to 7% for the target MC.

    Keep in mind that the environment the wood will be
    placed in is paramount. If it’s a newer house with
    solid climate control (humidifying in the winter), then
    you’ve got more wiggle room. If it’s a house that has
    a wood stove for the sole source of heat in the winter,
    then you better work on crafting an iron-clad
    disclaimer …. the joke for those kind of houses
    is that in the winter, the MC “goes negative”.

    So – generally speaking, I think your target MC is a little
    high – everything I’ve read indicates you get in way
    more trouble if your lumber is on the too wet side
    of the ideal, then if it’s on the too dry side of ideal.

    As an aside, I’ve lived in my house for over 30 years, and
    the only heat we have is a wood stove (6500 degrees
    days in the winter – I burn 6 cords of wood).

    I built my original cabinets out of tulip poplar
    way back – when I didn’t have a clue about how
    MC worked. By February each year, the panels
    in the wider doors would shrink so much, you could
    see light between the panel and the stiles.

    When we remodeled the kitchen a few years back,
    I asked the guy who did my cabinets to prefinish
    the door panels before gluing the doors up. I know
    things are moving more then typical (I have to tighten
    the door/drawer pulls around Feb every year)

    Hope the long winded reply is of some help

    Carl

    Reply
  9. Mitch

    I’m currently having issue with some 3/8 poplar nickle joint that was installed in a house in south Florida. It was installed in a variety of areas, interior walls, exterior walls, on plywood and on drywall. While there are a few boards that are cupped slightly the overall product looks great. Except one room that on two exterior walls the boards are cupping considerably more. The wood was installed over the drywall glued and nailed as a wainscot. There is considerable movement in this room unlike any other in the home. Any thoughts?

    Reply
  10. Ben cable

    I am a furniture installer who has been having trouble when fitting high end joinery in house here in the uk and abroad. The MC is fine and all checked prior to manufacture so I know this is fine, so my question is about the RH in buildings. What is the ideal percentage that I should be fitting in? And what is a too high and too low percentage to be installing in?

    Reply
  11. Steve Hamoen

    As an HVAC Contractor this is a reference piece that I will keep near and dear to my heart. This provides a starting point for discussions for all projects with a framework of numbers which in my mind is so much better than the qualitative discussions that lack empirical evidence.

    I just bought a MC Device and coupled with my humidistat we are now documenting all the entering wood in any new project that we take part in to ensure client success and assist the trim team.

    My belief is if we all point our fingers at the problem rather than each other we are poised for greatness.

    Thank you.

    Reply
  12. Midge

    I have 3/4 inch solid oak flooring. What is the acceptable moisture reading for the wood once installed. I have a cupping problem which I am told is due to moisture, however, the flooring reading are 14-16. The man who installed did not allow for the floor to acclimate to my home, He purchased and installed the same day. Please advise.
    Thank you,
    midge1975@bellsouth.net

    Reply
  13. Sandy Henry

    This is such a helpful article! This past summer I had to rip out and do a major overhaul on the deck on a recently purchased house. It is certainly amazing to think of the science and weather factors behind building and maintaining outdoor structures. The previous owners of the house set up a horrible mist system that mixed with our Texas summer and made for one giant project. Also, there was another great post that helped me understand how to work through having water features on our wooden decks safely http://timbertownaustin.com/home-improvement/how-to-make-sure-a-misting-system-doesnt-ruin-your-wood/ . Saved us the hassle!

    Reply
  14. Norman Keenan

    We are proposing to glue 6mm toughened backpinted glass to MDF or plywood panels to ceate a Glass wall. We are worried about which material will expand and contract more. The wall will be internal but will be in a large open Office reception. What do you recomend?

    Reply
    • Gary Katz

      Sorry,
      But for material recommendations you should consult a specialist in your area.
      Gary

      Reply
  15. najam

    Hi,

    I was wondering if you could advise… I installed some 3 1/4 prefinished maple floors on my main floor. I did it during the humid months of the year and the AC wasn’t running. We have had a long dry winter in Ottawa, and the gaps in my floor are huge. Some at 1/8 of an inch and collect all kinds of stuff in there! If the humidity goes up, will they expand? or is this possibly permanent? Also I was considering having them sanded with oak dust laquer filler and sealed with a water based sealant. Rught now with the gaps it looks so rough. Below is the basement with unfinished ceilings and fresh cold air for the furnace.
    Thanks! so disappointed…

    Reply
  16. Mary

    Hi,
    Thank you for your article. I have property in the northwoods of Wisconsin and over the past five years have worked with a wonderful builder. His work is consistently accurate, solid and tight. My projects in the past have been small – an interior remodel of a two bedroom one bath guesthouse, and the building of an enclosed garage. My latest project – building a 1200 sq. ft. family clubhouse – is my most adventurous and costly endeavor. The clubhouse is complete except for the interior wood. I originally chose t/g alder with a pre-finish stain but quickly realized that the $26,000 bill for 4000 sq. ft of material (for the ceiling, walls and floor) was beyond my budget comfort zone. So I am rethinking my choice of material. Part of my confusion – and the reason I am writing you – is that in the guesthouse project (completed 5 years ago) I used t / g cedar without any finish and have never seen any gapping or buckling.
    Question 1: Given your information about moisture content, was I just lucky in the guest house project or is my builder so good that he chooses only material that will not gap or buckle?
    Question 2: If I use a soft wood (kiln-dried cedar, pine or tight knot fir) in the interior of the clubhouse do I have to stain or seal it? My experience with the cedar tells me “no.” Your article says it will slow the movement but not necessarily stop it. If I purchase my lumber from a reliable company, and the material is kiln-dried is that enough of an insurance that I won’t have any problems with gaps or buckling?
    Question 3: Am I naïve in thinking that $26,000 is too much to pay? As this will be my final “big” building adventure I’d like to do it right.

    Thanks for your help. I look forward to reading your response.
    mary

    Reply
    • Gary Katz

      Mary,
      All wood should be sealed. Sealer doesn’t stop moisture content from changing, but it helps. The reason you had no problem with the cedar is probably because it was installed at the correct moisture content.

      We can’t make any comments about pricing. Pricing varies considerably from one region of the country to another.
      Gary

      Reply
  17. Pam

    Good Afternoon
    Would be most grateful if somebody could advise me on a water moisture issue. We had a sewage water leak from a pipe in the stack system unknown to us for 11 months , the leak was repaired but we didn’t realise the impact of the leak into the void space above the kitchen ceiling and under the shower floor which the timbers and joist was treated but brown stains kept appearing which we thought was perhaps the stuff drying out.. five months after the leak a water moisture was placed on the kitchen ceiling about 4 foot from the area which gave a reading of 17% without piecing. My concern is that l have a disabled person in the house who developed serious respiratory problems and took about 13 months before we realised that it was from the leak, in the next 4 weeks this person will be having major surgery so l am ensuring that l have done all what is needed, would 17% be what would have been when we had the leak or would this be a reduced reading, we also have horrid orange stuff in grout on the bathroom tiles appearing could this be connected Thanks for any advise you can give

    Reply
    • Gary Katz

      Pam,
      This article was intended to help carpenters and contractors understand wood and wood movement due to natural moisture content changes. There was NOTHING in the article about correcting damage from leaks. You’ll need to contact a contractor or mold remediation specialist in your area.
      Best regards,
      Gary

      Reply
  18. Brad

    Gary,

    Amazingly helpful article.

    Question: I live in SoCal, we bought a home with water damage. Our water damage specialist has dried the house slab in our lower floor to 11.2 and believes we’ve removed enough water. If I want to install oak flooring – A. Am I crazy and should consider a different material; and B. I’d like to install an 8″ wide engineered Siberian oak which is higher end in price.

    Any advice would be greatly appreciated.

    Reply
    • Gary Katz

      I wouldn’t ask your water damage specialist. I’d ask the hardwood flooring installers! Will they warranty the floor if you have them install it on an 11% slab??? I don’t think so :)
      Gary

      Reply

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