Lumber stored in shipping container

D6c · May 25, 2023, 06:15:10 PM

I have two shipping containers that I've been storing dried lumber in and I just recently moved them next to my shop so that I could run electricity to them for a light and outlet that I can use to run a dehumidifier.
Where they were sitting they had afternoon shade and never got very warm inside. Where they are now there's full afternoon sun and today it was pretty warm inside and we have hotter days to come.

My question is, is this going to harm the lumber, possibly by over drying or warping? They're weather tight but not perfectly sealed.
I didn't really think about this problem before relocating them. I couldn't leave them in their original location in the back yard and don't really have any other shady spot that would work.

doc henderson · May 25, 2023, 06:41:56 PM

mine is in fullsun, and when it is hot the RH drops and your humidifier will be off. runs about 20 ° over ambient. a tan colored container.

Ianab · May 25, 2023, 07:31:45 PM

I don't think you can "overdry" in that scenario. Inside of the container might get slightly warmer, and hence lower RH than outside, but that's really how you want to be storing wood. It's not climate controlled, but probably the next best thing. The RH in the box will go up and down on a daily cycle, but it's the long term average that matters, and that will be something "sensible".

You can work out the equilibrium moisture for a certain RH and temperature. Check both first thing in the morning, and mid afternoon, and that will be your upper and lower possible range for the wood. If conditions suggest EMC between say 10 and 6% over the day, then your wood is probably going to average around 8% long term.

doc henderson · May 25, 2023, 07:39:52 PM

I only run the dehumidifier about once a month. RH is 35% or less during the day. temp will drop at night, so if you want to dry it out a bit more, then run it at night. you can set the DH to 35 or 40% and it will only run when needed. Mine reads 70° and 35% RH now and I have not run the dehumidifier for a month.

Ianab · May 25, 2023, 08:07:41 PM

Quote from: doc henderson on May 25, 2023, 07:39:52 PMMine reads 70° and 35% RH now

And the calculator says that wood stored in those conditions should have an EMC of about 6.9%. It can't get any drier than that unless you up the temp or lower the humidity.