wood floor without a kiln

[LeeB]

I've got stacks and stacks of wood that has been air dried for years that I would like to use for flooring. Any chance it would turn out ok without kilning it first?

[WDH]

I think not unless you like large cracks in your floor. 

[starmac]

I know several guys that have done it here, but we have very little humidity, and they stacked it inside for a year or so first.

I'm thinking the humidity in your area would cause a problem.

[LeeB]

Thanks guys. I already knew the answer to this when I posted but one must keep the queen happy.  :D

[GeneWengert-WoodDoc]

Add to the shrink problem that will cause cracks, you also have a slight chance of having powder post beetles in the wood, which would be a huge problem.

With the years of air drying, you should be able to kiln drying in a few days.  So, maybe for $1500 you could build a solar kiln to dry the wood...or get the local community college of HS to build it and let them test it out with your wood.  Or donate it to a good cause once you are dry.

[mesquite buckeye]

Or just sticker them in the living room for a few months with the heat on in the winter. Don't ask how I know this. ;D 8) 8) 8)

[WDH]

You can turn your living room into a drying shed.  You can also sleep in the dog house. 

[Al_Smith]

Depends on what it is .I've got air dried ash that sat stickered inside for 4-5 years. I've made trim, window valances, wide window sills and a very nice raised panel fireplace mantle that has not shrunk a bit .

[WDH]

And, you must be single  :D. 

[Al_Smith]

 :D Ha I didn't mean stickered and air dried in the living room .In my shop. I'm some dumb not plum  dumb.

[longtime lurker]

In Turkey, at a place called Gordion, is an archaeological site called the Midas Tomb.
Midas was buried there, complete with wood floor, in 700 BC. It's the oldest surviving wood floor in the world.

I doubt it was KD.

I doubt most of the still standing and still lived in medieval buildings in Europe were built with KD either. Just well seasoned.

Maybe Gene can help with the history of kiln drying wood... earliest timber kiln etc etc. My guess is that pre industrial revolution kiln drying timber was seldom practiced, and probably never for something so plebeian as a floor.
Dress some, measure width with calipers, leave inside over winter, measure again. No significant shift = no need to kiln. Actually ditch the calipers... If the shrinkage isn't significant enough to measure with a tape measure then it hasn't happened.

[jueston]

In Turkey, at a place called Gordion, is an archaeological site called the Midas Tomb.
Midas was buried there, complete with wood floor, in 700 BC. It's the oldest surviving wood floor in the world.

I doubt it was KD.

I doubt most of the still standing and still lived in medieval buildings in Europe were built with KD either. Just well seasoned.

Maybe Gene can help with the history of kiln drying wood... earliest timber kiln etc etc. My guess is that pre industrial revolution kiln drying timber was seldom practiced, and probably never for something so plebeian as a floor.
Dress some, measure width with calipers, leave inside over winter, measure again. No significant shift = no need to kiln. Actually ditch the calipers... If the shrinkage isn't significant enough to measure with a tape measure then it hasn't happened.

unfortunately for Midas, he did not have AC in the summer or forced air heat in the winter in 700 BC... we humans create an environment dryer than outside, and in doing so we cause wood we bring inside our homes to dry down to that humidity and behave badly.

if we lived without AC or heat we could use air dried lumber without a problem just like Midas has been doing for 2700 years.

[Ianab]

Even with your climate control, it's still possible to use wood that's not kilned. It just needs to be air dried in the same conditions it's going to be used in.  So if you have a spare room or a climate controlled workshop you can sticker the air dried wood in there for a few months. It will do it's shrinking and moving in the drying stack, then you machine it to final size. Once it gets down to the ~8%, it's not going to move much more. How it got there isn't such an issue. 8% air dried wood is not significantly different from 8% kiln dried wood.

This is how Al's air dried floor boards are holding up fine.

Of course it's not commercially practical to do this on a large scale. A mill needs the wood dry and out the door in a few weeks, hence the normal use of kilns.

It's taking 12-15% air dried wood from outside, and putting that in a climate controlled house that's going to create issues. If the house is in a mild climate, and inside humidity is similar to the outside, and your 12% air dried wood is fine. No moisture change, no movement.

If we import American kiln dried wood into NZ, it has to be unstacked and left to acclimate for a few weeks, to GAIN moisture before you can put a floor down. Putting down a floor with 8% wood, in a 14% climate means the wood is going to expand in place.

[GeneWengert-WoodDoc]

For most people, air drying means that the wood is outside or maybe in an unheated shed.  In most of the U.S., that means that after a few years you will be around 12 to 16% MC.  Inside our heated homes, the moisture of wood is between 6% to 8% (maybe 9%) MC.  (Wood framing lumber is typically 12% MC in use and might be kiln dried to 19% MC.  A little shrinkage and warp is not a big issue.) As wood shrinks about 1% in width and thickness for a 4% MC change, even well air dried will shrink.  Although we did not have lumber dry kilns prior to 1850, we did have lumber stored in the rafters above a heated shop, which allowed the wood to reach the lower MCs required.  As mentioned, with interior heating, furnaces, etc. (and shipping based on weight and concern about warp and size, and concern about insects), kiln drying was an efficient, rapid way to achieve the 6 to 8% MC for interior wood.  In addition to kilns, as we know them, heated room drying is indeed an option.  In fact, such a room is often used for aromatic cedar to avoid evaporating much of the aroma.  All the wood in my shop was dried in my attic.  My shop is heated so that it has low humidity.

One key advantage of kiln drying hardwoods is that the heat (if the wood is over 133 F throughout) kills any insects and their eggs.

For softwoods, the heat (over 160 F oftentimes) in the kiln evaporates the sap and resin, so it will not ooze out later.

[Magicman]

This Ash flooring LINK did not go through a kiln.  The skidded logs lay for about four months before I sawed them.  It was then sprayed with boron and let air dry beneath an open carport for about 6 months before planning and T&G.  So far, so good.

[Al_Smith]

I'm certainly no lumber expert but in my limited experience it seems ash doesn't cup and warp as bad as say oak .It's fairly dry even in a green state and the eab killed ash in Ohio is hard as a rock .Fact a live ash tree is rather rare to find these days .

I like working with ash lumber which was once called  the poor mans oak .

[Magicman]

This was my first experience with sawing that amount and actually using it.  It was a pure pleasure.

[Magicman]

Oh and I forgot to mention that Dr Gene Wengert has personally walked on that Ash flooring.   ;D

[Al_Smith]

Just as a side note regarding kiln dried lumber. The house I grew up in is  a pre cut Sears and Roebuck .2800 square feet ,walk in third story attic .Douglas fir framed solid oak trim work ,circa 1919 .

That old  fortress is as straight as the day it was built, solid as a rock and I doubt seriously if one stick of lumber was kiln dried .It's nearly 100 years old .I doubt I'll be around the next hundred years but I'd bet that old farm house is .