# Drying wood in freezing temperatures?



## mpo414 (Nov 17, 2015)

I am having a local sawmill cut me some 4/4 pine boards for a project I am working on. When I get the wood it typically has a higher than desirable moisture content and requires some drying time. I live in Wyoming where we are quite cold already and (11 F out this morning). If I were to stack the wood in my unheated shop would it still dry or would the moisture freeze in the wood and prevent it from drying. I also have the option to stack it in my heated garage (I keep it about 55 F), would that be a better option for drying out the wood at these temperatures? Any advice? Thank you.


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## conifur (Apr 1, 2015)

I for got what it is called, but ice can go right to a vapor without melting. Put an ice cube in the freezer and over a few months it is gone.


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## conifur (Apr 1, 2015)

It is called sublimation


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## pjones46 (Mar 1, 2011)

That's called freeze drying. Sorry couldn't resist.


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## Yonak (Mar 27, 2014)

I would say it's called evaporation.


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## Dark_Lightning (Nov 20, 2009)

You can (well, my grandma did) hang wet clothes outside to dry in freezing weather (Minnesota), as long as it doesn't rain on them, and get them dry. It may take a little longer than here in sunny SoCal where we don't see much rain and is a lot hotter, but the physics is still the same. Especially in cold weather, the air supports little moisture. If you are looking for air dried, you should be OK.

It is entirely possible that drying could take longer in your shop, depending on what you are using for heat. What do you use? A propane heater will yield a lot of water as a combustion byproduct, and could actually delay the process.


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## conifur (Apr 1, 2015)

Well DL Natural gas and Propane give off a gallon of water for every 100K BTU used, but if vented to the exterior it makes no difference in the interior. Only if not vented to the exterior, exp a portable tube heater or radiant one, if like a gas furnace with a heat exchanger that H2O goes out the exhaust to the exterior/chimney.
To all it is not evaporation it is sublimation, a solid going directly to a gaseous vapor, evaporation is a liquid going to a gaseous vapor. There are only a very few elements that can/will do that. And no it is not the same as oxidation/rust.


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## Tennessee (Jul 8, 2011)

It depends more on the humidity levels of the air in your shop.
Temperature plays a part, but only in that the higher the temps, the closer it takes the water to its gaseous state so it will dry a little faster. But the wood will dry, even in zero temps if the humidity is low, which it generally is since water tends to fall out of colder air.


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## TinWhiskers (Oct 17, 2015)

Chart shows what Tennessee stated. Temp not the biggest factor.


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## TinWhiskers (Oct 17, 2015)

I am new at this drying. Just got 20 slabs late summer. Put them in my shop figuring it was better than outside. Started monitoring humidity. Humidity in the shop overnight will rise above what it is outside. Would the moisture in the wood raise the humidity in my shop? Heat has not been on much. 
Gas vented when it is on.


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## bondogaposis (Dec 18, 2011)

Yes, it will dry in freezing temperatures but at a slower rate. Slow is good when it comes to air drying lumber. I should mention that proper stacking and sticking is crucial for getting good results.


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## lndfilwiz (Jan 7, 2014)

Years ago, Mother Earth News had an article on drying lumber in Canada using a green house addition on the side of a work shop. The sun heated up the lumber during the day and heat care over kept the wood drying at night. The article stated that the lumber was sticked and turn every 2 weeks to keep from warping. In Wyoming you should have enough sun for this to work.


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## mpo414 (Nov 17, 2015)

Thanks for all the advice, it sounds like I should be able to dry the wood in my cold shop but it may take a little longer than if I were to stack it in my heated garage. The garage is heated with propane but it is a sealed combustion heater that is directly vented to the outside so it should not be adding a lot of moisture to the area. Our relative humidity levels here in Wyoming at 7,000' have been around 30% this week and temperatures during the day around 40F and at night 10F. I like the idea of a green house addition to the shop, that may just work out here. Can anyone point me to a link or another post or even just lend some advice about how you prefer to stack and sticker your lumber for air drying? I have been doing this to my current stacks but am not sure I am doing it correctly. Thanks again.


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## Mahdeew (Jul 24, 2013)

Main thing to consider is even air flow. So, make the row spaces equal to height spaces for air to evenly flow all around. If you are stacking it outside, make the stack to look like a "V" with either the point or the legs facing north in winter and south during summer months.


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## Tim457 (Jan 11, 2013)

Matt, you'll get good advice here, but it you want the details too, this is very thorough:
www.fpl.fs.fed.us/documnts/fplgtr/fplgtr118.pdf


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## mpo414 (Nov 17, 2015)

Tim, thank you for the link. I gave it a quick review and it seems like a great document. As a scientist by trade I can appreciate the detail and science to back everything up! I can't wait to read it in length. Thank you.


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## ThomasChippendale (Nov 6, 2015)

If it is 30% relative humidity outdoors and the temperature is 25 degrees F, and you heat the shop at 55 degrees F and there is a fair amount of air exchanged through cracks and door opening and closing, your relative humidity indoors is around 10%. This is very dry and if you put wet lumber inside, it will dry rapidly and the ends will crack a fair amount. Of course the humidity inside will increase as the wood releases its moisture but this moisture is rapidly replaced by the natural air exchange. If not you will get condensation on the windows and on your tools. I would say that this is too dry an environment for freshly cut lumber.

Evaporation: changing from liquid state to vapor
Sublimation: going from solid to vapor


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## splatman (Jul 27, 2014)

If you have not already, seal all the end grain, to stop checking. Would loosely covering the lumber with a tarp slow the drying to an acceptable rate in a 10%RH environment? Another possibility is to use a humidifier.

Phase transition on Wikipedia.


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## Dark_Lightning (Nov 20, 2009)

> Well DL Natural gas and Propane give off a gallon of water for every 100K BTU used, but if vented to the exterior it makes no difference in the interior. Only if not vented to the exterior, exp a portable tube heater or radiant one, if like a gas furnace with a heat exchanger that H2O goes out the exhaust to the exterior/chimney.
> To all it is not evaporation it is sublimation, a solid going directly to a gaseous vapor, evaporation is a liquid going to a gaseous vapor. There are only a very few elements that can/will do that. And no it is not the same as oxidation/rust.
> 
> - conifur


True enough. I was thinking of something like a torpedo heater that sometimes is not vented outside- which I consider crazy. Maybe I read that other post incorrectly. That has been known to happen.

Sublimation occurs with solid CO2 to vapor at -40° (either C or F, it is where the two measurement systems intersect), and iodine at about room temperature.


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## Adventurous1 (Mar 26, 2020)

I need to spray down the inside of an old wood barn to sanitize it, using watered down bleach. The temperatures here are still dipping below freezing (low 20's) at night. Is this going to damage the wood? Should I wait until the temps are above freezing?


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