Wood moisture for woodworking confusion.

N80 · Jun 23, 2025

As some may know, I have a saw mill and have been doing some woodworking projects.

I know that most sources say wood should be around 7-9% moisture for furniture and such.

I mostly dry wood in my basement which is not heated or cooled. Just stacked and stickered. It works but takes just as long as outdoor drying. White oak 6/4 boards took a little over a year to get down to about 11-12% which is about the best I can get. Because there is no HVAC for the basement the relative humidity varies and so does the wood humidity. In the summer, like this morning, relative humidity outside was around 95%. It is 60% right now at lunch time. It is humid here.

Right now, most I what I have drying has only been drying for 4-6 months and most everything is around 14%. But even old stuff is over 12%.

So I got to wondering what everything else reads. The house is almost 100 years old. Beams in the basement read about 12%.

Furniture in the house some of it 100+ years old is mostly around 8-9%. Same with interior doors and trim. 75 year old pine paneling in one room is 9.5% None of it is 7%. We do not have mold or mildew problems inside.

So now I'm wondering what my realistic goals need to be. Even wondering if it is possible to get wood down to 7% here.......or if it needs to be. I could add fans to the stacks. I could even make a little solar kiln. There is a large commercial kiln an hour from here and rates weren't to bad in years past.

But let's say I got some stuff kiln dried or solar kiln dried to 7-9%. If I don't keep the lumber inside the house itself (which isn't going to happen) isn't that humidity going to just come back up as it balances with the relative humidity?

dstig1 · Jun 23, 2025

Wood finishes slow down moisture movement a lot. So finished furniture will lag the ambient moisture quite a bit ion summer and then never fully match it, as once it turns winter again it will start to reverse. But a lot depends on the climate and you are in SC and I am in WI... Very dry winters with a long heating season making it worse. Very humid summers. You can watch the cycle in our wood floor. The gaps reach their minimum around Sept as the moisture has fully worked in as far as it will go before the cycle reverses and widest gaps are like Feb-Mar.

In your area with the higher moisture levels more year-round, you may want to shoot a bit higher and that 10-12% might be just fine. You will never get lower than that without a kiln, either. Allow for wood movement by making gaps a bit larger on pieces you build int he winter and tighter on those built in the summer. ...but you can still get caught, even doing this...

dadohead · Jun 24, 2025

I read a paper years back from a professor at University of Wisconsin. In it he said that dried wood left in a "conditioned" space (not a basement) climatizes to about 10% MC if left long enough. He also said it is surprisingly consistent across the country from the rainy NW to the desert SW. Air drying wood will rarely get to below 12% MC. After 2 WW apprenticeships (mill/cabinet & patternmaking) I find this to be true.

We start with dry wood (6-8% MC) and construct our work laidened with cross-grained joinery. As the job takes on moisture and expands, the captured wood is put into a compressed state and is stable. Building with air-dried wood, however, risks cracking as the completed work sees tension as it heads toward 10% MC and continues to shrink. Not a good outcome.