Storing dried lumber in high humid ambient

[Marc Jeske]

Not too far north of TX gulf coast here, like a steamy sauna in summer.

VERY humid ambient.


Let's say I buy 1k bd ft of dried SYpine, and want to store it in un conditioned portion of shop.

Or maybe even outside shop, under large shed canopy roof.... will not get as hot as the solar gain inside.


Let's figure part of this pile will be in this storage for a whole year.


Obviously keep off slab on like pallets, stay a foot or so from wall, no stickers needed cause already dry, ... but past that.. wrap w 6 mil Poly w tight taped joints?

Good enough?

Or... TWO independently sealed layers of Poly ?

Good quality not chinese Duct tape ? Foil HVAC tape ?

Also.. Should I add small strip heater like guys put in gun safes?

Damp Rid bucket or similar desiccant ?

Elevated above always dry slab, but under outside shed roof as good as inside ?


Any idea how to put like a big zipper access on the end of the stack so I don't need to screw w tape when pulling out a few boards?


Appreciate all comments, Marc

[Phillip Mitchell]

I think you're fighting a losing battle trying to isolate lumber from a humid environment, short of keeping it inside a properly conditioned building.

When you say dried SYP, do you mean from the box store/lumberyard or was it sawn locally and has been air dried for at least 4-6 months? I have very rarely experienced SYP from a lumberyard that is actually dry. In that case, you will want to sticker it in a place that has roof cover, but still allows consistent air flow all around the stack. If already completely dry then stacking without stickering can work, but I usually still sticker if stacking outside.

If you are getting lumber that has been properly air dried (or kiln dried) and you need to store it outdoors, the lumber will quickly reach its equilibrium moisture content, which is a function of the relative humidity where you are. Humid TX/southeast climate can easily look like 12% moisture content for dry lumber sitting outdoors in summer time. Winter will likely be lower because colder air can't hold as much moisture.

You can then bring the quantities you need to process and use for projects into your shop (conditioned space?) and let them acclimate (stickered) for a week or two (or more depending on a lot of variables) before you start to remove material, dimension them, cut joinery/use them in a project. If the lumber is properly dried and is given time to reach its equilibrium MC again inside your shop before you start to dimension it, then you will have done yourself a favor.

You might check out the book "Understanding Wood" by R. Bruce Hoadley. It is a lot of information, but is valuable in understanding wood and how it needs to dry.

Hope this helps. If I've got any of this wrong, please, someone correct me ;)

[Chris Fournier]

You won't win that game. Shop needs to be humidity controlled and the wood would need to be in it if you want it to be dry. How dry is kiln dried from your supplier is a question for you and I mean your own moisture meter kinda question. What RH is the finish project going to placed in. This is your target moisture level for your lumber.

[Dennis Ford]

Where would you get dried SYpine? "Kiln dried" construction lumber is stamped "SDry" which stands for surface dry (I call it sorta dry), it is actually about 18 - 19%.

[Marc Jeske]

Ok, read all responses.

Need to get an MC meter, check a few things out.


If I may, totally rephrase my question... forget the first post for a moment....

New question - If I have 10% kiln dried wood, and I airtight wrap it in 6 mil poly, VERY tight seams, and store it in that unconditioned side.... Will the MC change much over one year?

Can't see how it could if totally sealed.

Been reading stuff like this-
http://www.versaperm.com/images/water-vapour-permeability-chart.jpg


Anyway, that's really the question.

Thank you again, Marc

[Marc Jeske]

Looking at the Hoadley book - So he talks about poly AND possibly heating the storage enclosure... Page 156 - Note upper left 1/4 page text.....

I do understand importance of wood being dry before wrapping. Marc

https://books.google.com/books?id=5HBH2ibu-ZwC&pg=PA156&lpg=PA156&dq=storing+wood+in+polyethylene&source=bl&ots=coKHbIvjDa&sig=nhk6FoBHowkpq-aDQ5O94iGmtxQ&hl=en&sa=X&ved=0ahUKEwjr-7C2qZ7VAhUd24MKHa4GCCE4ChDoAQhOMAc#v=onepage&q=storing%20wood%20in%20polyethylene&f=false

[Dan Hahr]

I think you may end up with a moldy mess. Let air circulate around it, as in stickered. Plan on the wood moving a bit when you use it.

Dan

[Marc Jeske]

Getting a Ligno Scanner SD from a very kind Creeker.

So, I will have that to check before I buy stock.

Only local ( we live middle of nowhere E TX ) lumberyard has gorgeous SYP.. 6, 8, 10".... NO knots at about $1.70 /bd ft.

NO ink stamps on it to deal with.

Very anxious to check random in pile w the Scanner.


After research, assuming dry, I feel totally confident it will store just fine w proper wrapping.


Only thing remaining is finding a zipper, or making a readily re tapable slot for withdrawing a few boards at a time.

Marc

[Phillip Mitchell]

Is your shop space conditioned in any way? By that I mean, is it air conditioned or dehumidified in summer and/or heated in winter?

How much stock are you planning on processing/dimensioning per project and how long are your projects taking to build and take up space in your shop?

I'm asking these questions to bring up the point: what is preventing you from just leaving your stock outdoors (covered, stickered, getting airflow, etc) and bringing it in as needed for a project a couple of weeks before dimensioning? That is, by far, the least complicated way to proceed. Once you get into sealing wood up in poly, then you have to constantly be concerned with and react to changes in temp, dew point, relative humidity or else you'll end up doing more harm than good for your lumber. I don't intend to dissuade you from thinking outside the box, but you may be barking up the wrong tree with the poly approach.

[Benjamin Gonsalves]

I am a residential home builder in South Carolina.... a humid area. I also do a great deal of woodworking. That being said, I have tried unsuccessfully to "protect" seasoned wood from moisture gain. In theory, wrapping it perfectly would work.

In theory.

In reality, it seems to have quite the opposite effect. Aside from vacuum sealing the wood I am not sure anything would work. The pressure difference between the interior and the exterior of the poly wrapping will constantly be trying to equalize, and moisture WILL find a way in. What I can guarantee is that you will have made it much, much more difficult for the moisture to get out. Essentially, you're trying to go against the Second law of Thermodynamics, which states that water (even in vapor form) tries to search out drier places.

Even poly isn't a 100% vapor blocker, and some will inevitably find its way in. I have been fighting this battle for years inside buildings (think crawlspaces!) and have come to the realization that mother nature laughs in the face of human logic. Despite the best air-sealing practices of crawlspaces, a dehumidifier must still be installed inside an encapsulated crawlspace. Why? Because in the real world truly air-sealing is a myth.... and any Duct Blaster or Blower Door test will confirm this.

[Scott T Smith]

Do you have a hot attic that you can store the lumber in? Typically as the temperature increases air will absorb more moisture, so storing your lumber in an uninsulated attic tends to keep it dry as the RH% in the attic is usually much lower than RH% outside of the attic.

[Jim Becker]

I think you may end up with a moldy mess. Let air circulate around it, as in stickered. Plan on the wood moving a bit when you use it.


This...was also my thought.

[Robert Engel]

Greetings from swampy NE FL.....;-)

I would keep the wood stickered at all times to prevent mildew, insects, etc. I have lots of wood stickered and stored under a shed but no way can this wood be used. I don't use a moisture meter I just know from experience I cannot go straight from the stack to a project. I will bring the wood into a wood storage room in my shop and keep stickered for a few weeks, then cut to lengths.

After the stock is cut to length, it is stickered and stored in a climate controlled room for at least a month prior to use. The AC will get the ambient humidity to around 65%. In the very humid months like July, I also run a dehumidifier. This room is actually my hand tool room. I call it a "studio" but it is large enough to store project wood.

I keep all parts of the project entirely in this room during the build. I've found building the project in an environment similar to where its going is a huge deal.

My ww'ing experience is much very few disappointments with cupped panels, etc.

[Ted Reischl]

This whole moisture business strikes me as a way for someone to pontificate endlessly and write a book.

The idea that things should be built keeping in mind what the humidity will be in their permanent location is ridiculous. Things should be built keeping in mind that wood moves as the moisture content varies. An example. Wisconsin, Michigan, Illinois, etc. In the winter the humidity is typically very low, like 20 - 30% due to the cold dry air. People run humidifiers in their homes to keep their noses from cracking. In the summer, the humidity is the opposite. 80-90% is common. So what should a furniture builder do? Build it for the dry season or the wet season? Or make sure that whoever gets it maintains an ideal moisture level year round? How about, I bought a piece of furniture and then moved?

Furniture is built with dry wood so that joints do not loosen up during dry periods. They get tighter when the humidity is high. So one should build with dry wood.

Here is a thought for all those who get all tangled up in knots with overblown moisture discussions: The Newport furniture masters did not kiln dry their wood, the furniture went to all sorts of places, there was no air conditioning. And yet here it is, over a hundred years laters not falling apart.

About this SYP. It will grow mold, nasty black mold that will penetrate quite deeply into the wood. I know because a few years ago I had a bunch when we built the shop. Within a week or so it was growing mold. It had gotten a bit damp. Keep it under a roof away from any rain. Maybe draping a poly sheet over it loosely to keep blowing rain off it but allowing lots of circulation.

Another thing about this moisture business. I built a platform out of SYP PT. It has about 8 1 X 6 deck boards across the top. I screwed them down tight to each other knowing they would shrink. They did. What is interesting, is that they never seem to grow even when it rains every day for days on end. They are sitting outside fully exposed to the weather. So much for boards soaking up tons of water and expanding like crazy. Yes, boards expand, but it does not appear that they ever expand back to their original width.

Seems to me there is a disconnect connect between moisture content in wood and relative humidity. Obviously 100% RH is not going to result in 100% moisture content. Found this:

"EMC, Relative Humidity, and Temperature. The relationship between moisture content (as well as the equilibrium moisture content “EMC”) of wood andrelative humidity can be studied and approximated for a given temperature. ... True for most of North America, 30% to 50% relative humidity corresponds to 6% to 9% EMC.Mar 6, 2014"

at : https://www.wagnermeters.com/what-is-equilibrium-moisture-content/

I quit worrying about this moisture business years ago. If you notice, that says 30-50% RH results in 6-9% EMC. Think about it. I am curious what 100% RH causes in terms of EMC?

And I am not going to be suckered into buying some book that bloviates endlessly so a guy can make a buck.

[John Piwaron]

After perusing the other replies, I'll toss in my 2 cents.

Wood gains/loses moisture over time. You have a supply of material that you're not ready to use. If it were me, I'd keep it out of the weather, protected, carefully stacked and stickered and weighted down. That's it. What else to do? Bring it into your shop a couple of weeks in advance of use. Let it acclimate. That's probably as dry as it'll ever be.

Here's the biggest point - build whatever with allowance for wood movement. And it *will* move. Nothing can stop that. Nothing. No finish I know of, no wrapping in anything - nothing.

I'm a hobby guy, not a pro, yet nothing I've made has failed because the wood moved and broke it apart. I've got a cabinet in my living room that clearly demonstrates that wood moves. The top is now 1/8" narrower than when I made it. It simply dried out. How do I know? Well, I've got some trim attached with dovetail keys at the top. The grain of the trim is of course 90 degrees to said top. That's how I know how much that top moved. When I built it I allowed for even more movement. Same with raised panel doors, etc. Always build for wood movement.

Christian Becksvoort once published a short article describing a formula for calculating wood movement. That article appeared in Fine Woodworking years ago. I keep a copy of that article and some charts for wood movement in various species in my shop. When I build I refer that article and calculate the theoretical amount of movement and allow for that. Wood won't exceed 28% moisture content in any case. That's the fiber saturation point. Any more than that and there's be water dripping from the wood. Generally speaking I allow for an 8 to 14% swing in moisture. That may be more than anyone else does, but nothing I've made as failed because a panel caused a frame to break apart.

[Bill Dufour]

When I worked for the USDA 25 years ago I learned some government agencies insisted the pallets be made from kiln dried wood. This was mainly the military who had automated warehouses. The wood had to be kiln dried before the pallet was made but they did not care if it sat outside in a puddle and was soaking wet when it shipped. Government research shows that kiln dried wood is pretty stable after it is kiln dried.
Bill
Modesto, CA
The RH has been in the low 20's all last week but about 100 degrees. I let fence wood dry about 1-2 weeks outside before building a fence.

[Benjamin Gonsalves]

One of the ways I have gotten around some wood issues (think table glue-ups, or raised panel cabinet inserts) is to rip pieces into more narrow pieces, such as 2.5-3". Then, especially if ripped from the same piece of wider stock, alternate the face sides. Essentially, flip a couple pieces the opposite way, upside down, as they were ripped from the board. This really does serve to help the wood be more dimensionally stable. I am certain most of you know this "trick", but it has helped me on some finicky projects.

Other than that, the only other "trick" I use is to seal all edges of the wood, even if they'll never see the light of day. This helps the wood maintain a uniform moisture content throughout, which is half the battle.

[lowell holmes]

I live in Galveston County, Texas, 15-20 miles from Galveston Bay. I store my wood in the attached garage which is my shop.

I store my wood in a wall rack or some of it leaning against the wall. I use to check the moisture content of my wood, but never had an issue.

I buy my wood from indoor yards and buy seasoned wood. I don't experience any issues. Of course my shop is frequently too warm to work.

If you start with dry lumber and work in a shop, air conditioned or not, I would not expect issues, but who knows?

[Jim Becker]

One of the ways I have gotten around some wood issues (think table glue-ups, or raised panel cabinet inserts) is to rip pieces into more narrow pieces, such as 2.5-3". Then, especially if ripped from the same piece of wider stock, alternate the face sides. Essentially, flip a couple pieces the opposite way, upside down, as they were ripped from the board. This really does serve to help the wood be more dimensionally stable. I am certain most of you know this "trick", but it has helped me on some finicky projects.

This certainly can be effective...as long as you ( or the client if you are building for others) is fine with the altered look that narrower stock brings to the panel. For "me", it wouldn't work because of my profound affection for wide boards. :)

[Scott T Smith]

When I worked for the USDA 25 years ago I learned some government agencies insisted the pallets be made from kiln dried wood. This was mainly the military who had automated warehouses. The wood had to be kiln dried before the pallet was made but they did not care if it sat outside in a puddle and was soaking wet when it shipped. Government research shows that kiln dried wood is pretty stable after it is kiln dried.
Bill
Modesto, CA
The RH has been in the low 20's all last week but about 100 degrees. I let fence wood dry about 1-2 weeks outside before building a fence.

Bill, typically the requirement for KD wood for pallets is related to sterilized wood - not MC%.