Equilibrium Moisture Content of Wood in Outdoor Locations

That's not what you said...I was just trying to follow instruction...

 

The wood you send to Arizona or have kiln dried isn't going to stay that way once you bring it back.
Same rule applies as to flooring that you are supposed to set in the room it is going to be floored. Usually recommended for several days. You want all the moisture content to get to equilibrium so that aren't issues with dimensional instabilities.

Guys that use solar kilns that are successful with them usually manage fans well. Firewood and/or lumber.

 

Glad I could help you out

 

That's quite a bit of info there! Good stuff, and thanks for sharing. I'm looking forward to cracking open a couple splits later this month and seeing how far along they are. August was brutal with humidity here in CT, so we'll see what we've got.

 

One thing any type of kiln will do is get the moisture out of the wood a lot quicker than just on a wood pile for a significant period of time. I am sure a kiln will also get the wood dryer than just leaving it out. That is one advantage of a kiln both quicker and usually dryer. The again there is a cost to kiln drying wood.

What these tables show is that even if the wood is kiln dried after you set it out the wood will eventually reach the moisture level shown in the table. The big question is how quickly will the kiln dried wood increase in moisture content? My guess is that it will take some time.

Thus if you buy recently kiln dried wood say at the beginning of your heating season I imagine it will stay around the same moisture content for the heating season (some increase). On the other hand if you buy the kiln dried wood and waited a few years to use it, the moisture content of the wood would approach values shown in the table. Thus defeating the purpose of buying kiln dried wood.

I would be curious what other people's thoughts are.

 

It’s been pretty humid 80% or better here in Delaware for the last three months. Finally dropping now as are temps. I just got my moisture meter in today and tested a few pieces of wood and I’m pretty happy with the results considering I just split some of it. Lowest I got was around 11%

 

Nice you are making progress on getting your wood dry. I hope my pile is doing the same.

According to the table for Delaware the best you should be able to get your wood down to is around 13%. This would be for a "typical" August which can vary from year to year. For Wilmington DE it is showing around 13% moisture content for wood through the rest of the year is the best you could typically get.

I am sure there are times when the humidity at times has been around 80% especially in the early AM when you have dew but imagine it was more in the 50-60% RH during day though in the 80's and 90's during the day.

The problem with using the table that shows the relationship between wood moisture content and relative humidity is that the relative humidity typically goes up and down each day and especially in the summer. You rarely if ever have a constant relative humidity for very long. During the day the relative humidity is lower while at night as it cools off the relative humidity increases. If you see dew on your car then due to it getting cooler at night the relative was 100% causing water to condense out of the air.

Thus unless you have a controlled environment where you can keep the relative humidity constant where you store your wood one needs to be careful using the table showing the relationship between moisture content of wood vs. Relative Humidity IMO.

It looks like you have the same moisture meter that I have. I wonder how accurate these meters really are? Does anyone know?

 

would say your pretty much spot on. One factor that may need to be considered. Dry wood has cells that shrink. I would imagine the dryer the more shrinkage. This should be a factor into how much more moisture the wood will accept, maybe.

 

I had a pile, not stacked, of mostly dead oak that was 3 year seasoned, now 4. Uncovered. It was removed from my mothers basement last December and dumped on a concrete pad. I’m bringing it into my basement this year. I need it out of there.
Cracked the largest split of oak today. 18%. I’m happy with that considering it’s been uncovered. Found a piece of ash in it that my mom scrounged from my processing area. Yes, she’s a wood thief. 1 1/4year seasoned. 15%
I’m interested to see what some of the stuff I have top covered is myself.

 

Appreciate the info. I certainly hope it’s pretty accurate. I can’t wait to start testing all my wood splits! Wondering how far do U have to push the prongs in? Also, should I split the piece in half to get a reading from the inside?

 

Yes, must split fresh. Readings on the outside have no value. You don’t need to poke the pins in far. I’ve had the real cheap Chinese MM’s and pushing with any force would break them internally. A fresh split doesn’t require any real depth and now you know what the reading is at the center.

 

They say the only way to get a true reading for wood is split the wood and then do a moisture reading. Reading moisture content otherwise isn't accurate, e.g. taking a piece of wood off the wood pile and reading its moisture content without splitting.

 

So the theory is that wood can dryer on the outside vs. the inside? Thus by reading the moisture content of freshly split wood you read what the real moisture content is?

 

Absolutely. That’s a given.

 

Nice article!

The last graphs show why it is valuable to bring wood inside a few days before burning it. Of course, it isn't going to reach equilibrium in a few days. But that first outside mm is going to be a lot dryer after a few days than it was before. And that first outside mm is where it starts burning.

 

Absolutely. Any water not in the wood water that you are not boiling off. Near the surface or at the center water is still water.
I’ve weighed pieces that were brought inside a few days before burning and kept near my stove. I’ve found that they drop an additional 1-2 points of moisture content. Reducing the amount of water that I am putting in my stove is fine by me.


Using a scale sensitive to a gram you can see wood adjusting to changes in the relative humidity between day and night. Weighed at sunrise and sunset, a piece of wood in its latter stage of drying or at equilibrium will gain a gram or two or more at night and lose it the next (sunny) day.

 

So u guys were spot on! I split a few pieces that I tested yesterday and found the moisture content significantly higher around 30 or better. I’m stacking it outside facing the wind and where the sun will hit it for the better part of the day. Just hoping I can get some down to 20 before winter. So disappointed I didn’t start sooner. I will be bringing in a bunch so that the stove heat will dry it out a bit.