Storing Lumber Outside

[Mark W Pugh]

I want to store my KD lumber outside underneath a cover I built off my shop. The wood could possibly get some rain/snow, if there is a strong storm. The lumber will be stickered to allow airflow.

Any problems with this. I'm sure this has been done for hundreds of years, but just checking.

[Michelle Rich]

the problem I see is the water stains you might get if the water gets under the cover. To put KD wood out & soak it, does not seem prudent. We all have storage issues with our wood supply, but the method you are suggesting is used for wet wood to dry, not KD wood to store.

[Matt Day]

Just keep it dry and being outside should be fine. Maybe hang some tarps or something for "walls". Remember most lumberyard store lumber outside and unconditioned, but it's dry.

[Dimitrios Fradelakis]

the problem I see is the water stains you might get if the water gets under the cover. To put KD wood out & soak it, does not seem prudent. We all have storage issues with our wood supply, but the method you are suggesting is used for wet wood to dry, not KD wood to store.


How do you suggest storing KD wood outside if one doesn't have a shed?

[Bradley Gray]

You might consider plastic vapor barrier on the ground under your storage area with a bit of gravel to hold it down.

I don't sticker dry lumber.

[Danny Hamsley]

Don't sticker it if your wood is kiln dried, i.e. below 10% moisture content. Leave it flat stacked so that the humid outside air cannot get to the boards. If you wrap it in polyethylene plastic, that will prevent air exchange and your lumber will stay drier for a much longer period of time. You must protect it from the elements, blowing rain, etc. If you do wrap it in plastic, don't let it get wet under the plastic. Wrap it tightly and waterproof it, and you will be fine.

[John Blazy]

Wow - I cant believe these replies aside from advise to wrap in plastic. Never store KD lumber outside. And the comment about lumber yards storing lumber outside? - yes, that is for construction lumber, not hardwoods. Most cabinet lumber is air dried with stickers to Equilibrium Moisture Content (about 20%), then kiln dried the rest of the way down to 9. If you store it outside, you completely nullify the KD procedure, as it will re-absorb moisture coming back up to EMC.

Then if you build something with it @ 20%, you will get warps, bows, open miters, splits, etc.

I would say that even wrapping in plastic is risky. I never stored KD lumber outside when I ran a cabinet shop. If you wrapped in plastic, make sure its double wrapped, on all six sides, and don't let anything puncture the plastic til you use it, then reseal after pulling boards. One small leak and now the plastic becomes a greenhouse - certain to take MC back up to 20 or more.

[Yonak Hawkins]

I'd like to hear a studied response on this rather than conjecture (such as mine) and anecdotes but it's my opinion that once the lumber has been dried from green lumber, any subsequent absorbed moisture evaporates pretty quickly when conditioned in a dry area. Once dried, lumber can't return to a green state that takes months to cure (unless the lumber has been soaked for a very long period of time). I've seen areas with dried lumber get flooded and, after being aired out, the lumber returns to a low moisture content within a couple of weeks.

[Sean Shannon]

I was just at the hardwood dealer yesterday. All of there lumber is stored outside undercover where no water can get on to it. The other various dealers I've visited store their lumber in a unconditioned space out of the elements.

[John TenEyck]

I remember seeing pictures of Garrett Hack's open outdoor shed where some of his lumber was stored. And I used to buy my hardwood lumber from a local shop where it was stored in an open shed. Never had any problems as long as I let it acclimate to my shop for a couple of weeks. KD lumber will never go back up to 20% MC unless that's what the EMC is where it's stored. Where I live in WNY the EMC is about 12 - 14%, so that's as high as it could ever go.

I would do as Danny and others have recommended.

John

[Robert Engel]

Pretty much what Danny ^ said.

I would probably put down a ground barrier down and keep the wood at least 8" off the ground.
I stack mine on cement blocks with 4x4 posts every 2 feet. Level everything first.

[Brad Shipton]

I see you are located in Ohio. I am not that familiar with the humidity in many of the US states, but I suspect you are relatively dry and not anywhere near tropical like Florida. So what is the difference inside and out? Temperature, moisture, and humidity (if shop were to have a humidistat). The temperature is not going to affect the lumber, so if you keep it dry I do not see a problem. Obviously, inside is better, but if you do not have a choice this seems reasonable. I have a wood slab inside a box elevated off the ground and under a tarp right now too. I do not have space in my shop for a couple of months and I found a wood slab that was the right size for a project then.

[Wayne Lomman]

John Blazey is 100% right, it's a no-brainer. If your timber is KD, store it inside in a stable environment. It is the only way to be sure that you keep it in good condition. Wetting and drying cycles lead to surface checking with the end grain most susceptible. If you have to build a lean-to on your shop to store it, make it a bit better so that you can fully enclose it and keep the weather off - in other words, it is still stored indoors.

What we are talking about is what is the right way to store KD timber. There are plenty of ways you might get away with storing it, but there is the correct way as so aptly put by John. That being said, every shop has limitations and you sometimes have to just do the best you can. As some idiot says, makes sure you understand what the rules are before you go out and break them. However, breaking the rule does not invalidate the rule. Cheers

[Yonak Hawkins]

This is very informative, Wayne. Where did you get your information ?

[John K Jordan]

I want to store my KD lumber outside underneath a cover I built off my shop. The wood could possibly get some rain/snow, if there is a strong storm. The lumber will be stickered to allow airflow. Any problems with this. I'm sure this has been done for hundreds of years, but just checking.

Mark,

Yes, wood has been stored outside and used for hundreds of years. However, air conditioned houses with very low humidity are relatively new so the definition of acceptably dry lumber has changed, assuming the lumber is for making furniture instead of shovel handles.

I read most of this thread saw some confusion. You certainly can store KD wood outside. It will pick up moisture. It will lose moisture when brought back inside. One important thing to consider is time.

Anyone playing with wood would do well to educate themselves. An excellent resource is "Understanding Wood, A Craftsman's Guide to Wood Technology" by R. Bruce Hoadley. You can get it from Amazon for around $20. Hoadley will give a good education on wood structure, movement and warping, free and bound moisture, air and kiln drying, solid and structured wood, and much more. I bought this book over a decade ago and have used it so much the pages are getting loose.

For those unwilling to buy a book, there is good information on the net. My advice: Don't bother with the widely varying opinions on the forums but read the documents. For example, this excellent PDF file from the US Forest Products Laboratory may help: www.fpl.fs.fed.us/documnts/fplrn/fplrn268.pdf (http://www.fpl.fs.fed.us/documnts/fplrn/fplrn268.pdf) This short PDF has good information without being overly technical plus charts and tables of the equilibrium moisture content (EMC) throughout the year for all over the US and the world.

Armed with knowledge and ideally a good moisture meter a wood worker becomes invincible! (well, not quite, but at least empowered)

Here in TN, the outdoor EMC is something around 12-14%, not much different from Ohio. Hoadley mentions that in New England lumber stored outside will eventually reach 12-15% MC. Indoors depends on the humidity and temperature.

An unprotected KD board at 9% EMC taken outside will start to absorb water immediately through the ends and the sides and will continue to do so until it reaches the outdoor EMC. When brought back inside a conditioned space it will start to lose moisture until it reaches the its indoor EMC. The biggest question is: how long does this take? The time depends on the temperature and humidity of the space, the weather, the wood species, the thickness, and how the lumber is managed.


From the PDF referenced above:

...Kiln-dried lumber that is stored in high
EMC conditions can regain moisture, thus negating part of
the results of drying....If the EMC is high enough and storage
is long enough, the lumber can increase in moisture
content, which can create problems in product manufacture or
performance of an end product. There are several ways to
minimize this problem, including wrapping the lumber in a
moisture barrier or storing it in an air-conditioned facility.
One simple and not too costly method to lower EMC in an
enclosed space is by simply raising the temperature above
the outside ambient air temperature...

From what I have read, to store KD wood outside I would stack it tightly (no stickers), seal it the best I could (plastic wrap would be good), and store it out of the rain in a covered area (barn, shed) well off the ground with a moisture barrier directly on the ground. One of those metal carports would be ideal as would a portable storage building. Another option if permitted is a metal storage container. A lean-to can be easily built on the side of an existing building if code allows.

If I didn't have a covered area or a friend with some extra space I would put some spacers on the top, add some boards, and cover with either a flat roof made of metal roofing or sheet stock extending on enough to keep of the direct rain and sun. If using a tarp I would be careful to allow plenty of ventilation at the sides and out the ends so excess moisture would not be trapped under the top. Any top will need to be tied down or weighted to keep it from blowing off.

Storing wood is similar to storing hay outdoors where a tarp is best tied down with anchored ropes to make a tent. For hay on my farm, I purchased an aluminum shipping container 8x40x8 ft high and added vents to the top and sides. This would be fantastic for wood storage too.

How long does it take for wood to pick up and lose moisture? You might do an experiment to get a good idea of how your storage management is working. Check the moisture content of a "typical" board before storing it outside, then after a "typical" storage time cut off a piece and check the moisture again. Bring the piece inside and recheck at periodic times.

I do store a lot of wood outside, in a small trailer that sits in the sun and gets very hot inside, in the barn loft, in a portable storage building, and in a shaded 45' big rig trailer converted to a storage building. I gradually move this wood into my shop with heat and air and let it sit for months or years before use. (mostly woodturning) I use a pinless moisture meter that will tell me the moisture within an inch or so of the surface, perfect for lumber. Thick turning stock is another chapter - I keep many thicker chunks in the small trailer in the sun which stays pretty warm inside except in the winter.

JKJ

[Mel Fulks]

I worked for years in a shop that was started about 1900. All lumber was stored in an open front metal roofed shed. Some that we used only occasionaly was black from coal burning heat in the houses around us. Kiln drying is a permanent change. Stuff that we used for things like wide panels sometimes acclimated for a day or two in the shop but many times was in just long enough to warm a little for gluing. We had moisture meters but the quality of wood was mainly assured by always buying from the same sources. Yes, sometimes with small orders a little shrinkage or a crack or other flaw might just be accepted ,but the company was considered the best in the area and charged accordingly. Did a lot of churches and large homes and flaws were not cheerfully accepted. But if better storage is available then one should use it.

[Allan Speers]

Mark,

Make sure to heed the previous suggestions of laying down a good moisture barrier. I once lost many thousands of dollars of lovely wood due to ground moisture getting trapped inside my tarps.

Also: Thanks to suggestions here, I no longer use tarps at all. Corrugated metal roofing last a lot longer, and is not really very expensive. Even good tarps break down over time, from UV light, and then start leaking.

[Bob Bouis]

The answer depends on how long you want to store it, what kind of wood it is, and how it's been cut. If it's already milled or is a perishable wood, sell it. Only dead/flat stack if it's very short term storage [and be careful doing that at all outside]. If it's going outside for more than a month or two you might as well sticker it. Otherwise you'll end up with very uneven moisture content even if it stays out of the elements. Flat stacked wood that gets rained on will be ruined quickly.

Also, I agree about not using tarps. And a moisture barrier won't do any good unless it's completely covered. If your moisture barrier gets rained on, it's going to be a water trap / mosquito farm.

[Wayne Lomman]

Yonak, same sort of places John K Jordan refers to and decades working at the top end of furniture and cabinet making mixed in with spells in the bottom end of the trade where all the problems showed up. Cheers

[Mel Fulks]

I don't dispute that material picks up moisture ,but the kiln drying greatly limits how much the wood moves . I've posted twice about testing done with same piece of wood with some air dried and some kiln dried in a fine, large computor controlled kiln.

[Cody Colston]

Lumber will acclimate to its environment. Even kiln-dried lumber, stored in an average 12% EMC environment will eventually abdorb moisture until it is close to that value. It won't quite get there due to the hysteresis effect but it will become too wet to use for indoor furniture.

Garrett Hack works with "air-dried" lumber but he brings it into his shop and lets it acclimate before working it. He doesn't like to use it until the MC is at 8%. He told me so in an email when I had questions about using air-dried lumber.

I have my lumber stacked and stickered outside, covered only by roofing tin. Before I use it, however, I dry it in my solar kiln and then bring it into my shop. Since I run an A/C in the summer and heat in the winter, it will remain at the 7% MC or so.

Danny is absolutely right about dead stacking and wrapping in plastic if you want to prolong the kiln-dried MC. As long as the plastic is sealed well and has no holes, the wood will not absorb moisture. Blazy is also right that if the plastic is not fully sealed, you will eventually have a moldy mess.

Kiln-dried and air-dried descriptions are totally misleading regarding lumber MC. You want it around 7% for indoor furniture. Disregarding the sterilization aspect of kiln drying and assuming the lumber isn't steamed, there is virtually no discernible difference in dry lumber, regardless of how it arrived at that value.

[Mel Fulks]

Just a brief recap of test : pieces were cut adjascent from same board. Walnut about an inch thick ,2 inches long ,about 11 inches wide. Soaking in water caused very little movement on KD sample .Air dried gained 1/8 inch. On third wet -dry cycle the kiln dried sample and air dried samples reacted in same way. The samples were totally submerged over night. In practical commercial millwork the spec is "kiln dried". Not where or how to store it

[Kevin Jenness]

I am on board with all Cody said. With some species in some situations you can get away with using lumber that has been stored outside, but it is far better to make sure it has acclimated to the conditions anticipated in use. Here in VT lumber stored in open sheds runs around 12% MC and can take a couple weeks in my solar kiln to get down to 7%, again depending on species and thickness. I have seen tightly fit biscuited miters in 2"x2" hard maple open up to where you can throw a cat through because we had to get a job out the door using properly KD material that had been stored in a shed (bought from a reputable mill that ships internationally, stored in their open shed and checked before use at 12%). Regardless of the spec, if the work fails because of improper storage disappointment will follow. I am not denying your observations, Mel, but the fact that the third cycle produced similar results suggests that kiln drying is not sufficient to avoid movement in finished pieces if the material is fabricated at an elevated MC.

[Mel Fulks]

Well,total soaking is different from exposure to high humidity, wood exposed to very high humidity for some time doesn't get soaking wet! In my experience the only real problems have been from buying on price. I've had a couple employers say things like "we never use poplar because it comes in all wrinkly,cupped, and crooked". Well, spending 5 to 10 cents more a board foot solved that problem. The most succesful people I've known only bought KD wood and only from the same consistently dependable suppliers. Any "good jobs" requiring using some species unknown to them or known to be difficult were looked at
with serious skepticism. All the raised panels we made were of solid wood, today many of those jobs would be done with sheet goods. But we had no problems. I think some ,if not all , the churches with paneling had the thermostats low during the week and went through non stepped temperature increases often. My experience with furniture in my home has been that old pieces made before kiln drying show seasonal movement while the modern stuff does not.