Does anyone here use moisture meters to test there timbers before working on them? If so, what brands do you recommend, and what would you consider a good moisture content for stable wood?

Thanks,

Tim

Lots of people will throw out numbers for what they consider good moisture levels, but in the end stable moisture is reliant on your local absolute humidity levels, absolute humidity being how much water is in a certain volume of air rather than how much water is in that air compared to how much it can hold at that temperature (which is relative humidity)

The stable moisture level will be significantly lower in Arizona than Indiana.

Here in humid Indiana, we will generally consider things to stabilize around 12 to 15% moisture content. I have heard that in some places that level can be as low as 6%.

Now from here on lets be careful lest we turn this into a green framing v. seasoned framing debate... (I am on the green side myself) But suffice it to say moisture level is only a concern to some. There are those who use carefully dried timbers in their frames, and there are those who put it all together green. If you are letting your own timbers air dry, then you need a moisture meter. If you are doing with green or Kiln Dried wood, then you don't really need one, unless you are operating your own kiln of course.

Tim,

That's a good question. We've looked at buying a MM several times and still haven't for some reason. I'd be curious to hear from those who have and use them for timbers -- I couldn't find anyone with directly relevant experience when I was looking.

The reason we would get one is if the specifications on a high end job called for the timber to be below a certain number -- 19% is the one I see in specs most often. In that case, it would be helpful to be able to verify that my supplier is meeting spec and that my product after fabrication is meeting spec.

DL is right that equilibrium moisture content varies regionally. Here in the humid southeastern US, I consider 12% to be EQMC.

One thing to note is that there are two types of moisture in wood -- bound water and free water. the free water is the water that exists outside of the wood cells. The free water is the first to evaproate. For most species of wood, once the free water is gone and all that is left is bound water you are at around 30%MC. It's important to note that this is the point at which shrinkage begins -- when the cells begin losing the bound water. It continues until equilibrium MC, which is dependent not on relative humidity but absolute humidity levels as DL said.

(As an aside and not to encourage a green vs dry debate, I believe there is ample historic evidence that many high-end buildings were built with dry wood. I'm talking churches and great halls, not average residential buildings. In our work the same is true -- high spec/high end projects usually use the more expensive dry material while "normal" jobs use green.)

Lots of specs written for '19%' - but with a standard meter you'll only see that to about 1" of depth. What happens beyond that is anyone's guess.

I'm not sure how useful it would be beyond 'That looks drier than that timber'... especially working in green material, or even conventionally kiln dried material - where you can only get the timber (unless it is narrow / small) to give up a portion of its moisture on the outside.

The RF folks out west have a pretty sophisticated method of seeing inside timbers:

http://www.fraserwoodindustries.com/index.php?action=products.heartdry

still wanting not to go into this debate, I think Gabel brings out a good point. High end projects might require, and be able to afford, kiln dried wood.
In the old days in Continental Europe at least (can't speak for England, Ken may have to chime in on that) some timbers were allowed to season for a time. This was done either for high end jobs, or for a few vital timbers on other jobs where shrinkage might be catastrophic. The method of drying was not to use a kiln, but rather was to store hewn timbers in some out of the way location for several years. This would not stop checking, but it would keep the timbers from moving in situ.

It is also important to note 1 thing regarding green timbers.
In the old days, the trees were carefully picked and cut at the exact right moment if they were to be used without seasoning. In Germany this right time is between the middle of November and I think the New Moon around the end of January, first of February. Although it could be the full moon I am not quite sure. The reason for this being that during this time period the moisture content of the wood is at its lowest (the moon cycle affects when the sap comes back up into the tree)

How about weighing the timber and comparing it to a known dry weight?

I am starting to stock pile brace stock for future use. And more importantly, naturally curved stock would be nice to select from. As I walk around my mill yard I can point out the dryer piles, they are grayer.

While on the topic of dry timber, I recently uncovered a pile of timber, it had a tarp over it, there was more ice on the covered timber than an uncovered pile. I just swept the dry snow off the uncovered pile, I will be scrapping ice off the covered timbers. I suspect moisture from the ground could not escape the tarp and froze on the timber, and or some of that free moisture coming out of the timber got stuck under the tarp. It was not covered all the way to the ground, either.

Hi everyone

Great topic and quite controversial I must say with everyone having a little different slant

As one of the old timers in this group I thoroughly enjoy the back and forth ideas and pointers.

At UCV we had quite a historical maintenance department headed up by one of the best architects in Canada, what he demanded for special timbers (ones that would be used say inside a mill or heated home) needed to be processed either hewn or sawn depending on the situation and stored in open sheds for a period of 3 years, well stickered, a period longer than this required a repiling and realigning the spacers to allow the timbers or sawn lumber to recover at the sticker points, and prevent points of rot to happen.

Even after this length of time the timber is dry only down to the relative humidity of the surrounding air. The longer the storage time the deeper into the timber the stability penetrates

I thoroughly agree builders from time gone by had a better choice and control of the timbers quality, by the fact that most timbers were harvested during the cold dry part of the year and gave the curing process a real kick at the can. The same can be saidof firewood white ash harvested in the winter can be burned immediately

NH

For NH,

Beechwood fires are bright and clear
If the logs are kept a year
Chestnut's only good they say
If for long it's laid away
Birch and fir logs burn too fast
Blaze up bright and do not last
Elm wood burns like churchyard mould
Even the very flames are cold
Poplar gives a bitter smoke
Fills your eyes and makes you choke
Apple wood will scent your room
With an incense like perfume
Oak and maple if dry and old Keep away the winter Cold
But ash wet and ash dry
A king shall warm his slippers by

An old english saying

hi everyone tonight

Hi timbeal and others looking in

well timbeal you are a poet and don't know it for sure


Nearly everything is true in that recital except the line about elm--I grew up burning elm it was the backstay of our wood supply for the winter-we had lots and boy would it burn andheat well,sure nothing wrong with elm in my books better substitute another type of wood

It really wasn't a good lumbering wood other than for timbers, and joists were ungodly strength was needed due to bending and loading


NH

Hi All,
Sorry about the new username, this is Don P. I apparently broke off my key in the lock awhile ago. Anyway...

I use an older Delmhorst pin type meter with 3" insulated pins on their largest slide hammer. These meters are basically measuring resistance between the pins, in billionths of an ohm from what I understand, and convert that to a moisture content. an insulated pin reads only at the tips, so as I drive them in I'm reading the mc at the depth the pins are at. As I drive in I'm reading the "moisture gradient" from shell to core.

A high gradient is telling me that the shell is drying and shrinking around a still green and swollen core, great checking potential. A uniform reading tells me the wood is probably approaching emc... which is not a fixed moisture content anywhere. It averages about 12% in an outdoor (unheated) under shelter location here, in the VA Blue Ridge.

Gabel is pretty much right on in his comments, free moisture is the moisture within the cell lumen, bound moisture is the moisture that is chemically wrapped up with the cellulose within the cell wall itself. The point where the free moisture has left the cell cavity but has not yet begun to leave the cell wall is called the "fiber saturation point". As the bound moisture leaves the spaces within and between the cell wall fibers shrinkage begins, mechanical properties change.

A couple of interesting things happen right there, fungi need free water, as the wood dries below FSP fungi lose interest. FSP is a cell by cell point not an entire stick of wood point, remember the gradient above, the shell can be well below the FSP while the core is well above it. Drying commodity lumber down below the FSP is one way of making sure it won't decay while dead piled in a lumberyard... if they store it properly. Nowhere in the US is 19% emc though, the wood still has drying and shrinking to do from that point down to EMC. As the fibers dry they become tougher and stronger, carpenter ants cannot chew through them easily, they go looking for saturated wood.

The moisture content of a living tree does not drop in winter and in fact is sometimes higher in hardwoods where the leaves are not there to cause transpirational losses. Evergreens are evergreen because they are still growing and photosynthesizing through the winter... whenever the temperature allows the sap to flow. Winter cutting does give the wood the opportunity to dry with low moisture gradient through a period when fungi are halted by the cold, hopefully by the following spring the wood is below FSP and you can stay bright and fungi free, so there is good reason to winter cut but it isn't because sap goes down, it doesn't. Cells that embolize die, a tree cannot re-establish a broken water column.

This is a shot of my meter in some supposedly 17% cypress logs that were sold by a crook.

The top left part of the pic shows a dry shell... below fiber saturation point and a wet core, above fsp. When you can see the moisture you are seeing the free water in the cell lumen. When it looks dry you can say that it is below FSP for that species, that is all you can say at that point, but that is no small amount of knowledge right there.


If you know the temperature and relative humidity you can determine the equilibrium moisture content. The thermometer/hygrometer is giving that part of the equation here. If you look up the emc you'll see the meter is pretty much agreeing with those conditions. It's always a moving target, the temp and rh would have been a bit different a few hours before that and were surely a little different a few hours later so the emc will be within a % or so of that reading.

Timbeal had the most accurate suggestion, meters are ok but weight is the most accurate way to determine moisture content.

I had typed out a long response to this, but I decided not to post it. Might be seen as an offense or even an attack which is not what I want to do.

Now what interests me the most is the idea of moon cycles. I have read some about the old traditions in Germany. Trees to be cut for carpentry are always cut in the winter, this works well because generally you can't build a house at this time of year, so it gives you a great opportunity to cut and hew a lot of timber. BUT, you don't just go and cut down a tree or two a day, and do that all winter. Instead, you go around and choose your trees carefully, and decide what traits you want a tree to have. Do you want it to resist bending? Do you want it to resist tension? do you want it to maintain its shape as it dries? and so forth. (Keep in mind that this is done with oak in mind, or in some cases pine or whatever other material is available locally. The Germans don't use varying species for different characteristics) You pick the trait you want, and on a specific day you cut down the tree and it will have those qualities. Even the hour of the day is believed to be of importance. In some cases you cut the tree at night. What determines the right day is the cycle of the moon. I believe one important day generally falls somewhere in the neighborhood of February 3 or so.

This is interesting. We are tempted to say this is all a bunch of superstitious hooey. But the Germans didn't give a superstitious explanation for it centuries ago, they said simply that the moon cycle had some effect on the way the tree grew and so on. Today we know that moon cycles do, for some odd reason, have some effect on plant life. (Purdue University, I believe, has done some study into this area, and found that it is so.) Back in the day we all used to plant and harvest according to the moon. Some people in recent times (in regards to gardening) have discovered that the moon does have an effect on the early stages of plant growth.

So maybe moon cycles have an effect on trees. It would be an interesting study (although one that would take many years to produce any kind of conclusive results) Me, I'd like to learn about it and apply it to some degree (maybe for my own house?) if for no other reason than just as a curiosity.

DL, superstitions are often rooted in some type of fact. When we try to tease facts from the superstition... that's where I think we often go astray. I would be interested to hear more about your findings about timing of felling.

Right now the taps are in the maples, the sap is flowing, it is full of sugar. The temperatures and day length have triggered an enzyme reaction within the trees, stored starch is being converted to sugar and I believe co2 is the "pump", being released from that reaction to initiate flow. The old ADP/ATP cycle that I'd have to read up on to discuss. Sugar, starch, and cellulose are just different combinations and builds of C,O,and H. Right now there is a tasty fluid coursing through the maples' fiber. Tasty to an ambrosia beetle, I pass one tree daily that they have so thoroughly riddled that it is wet and can be smelled a half mile before I get to it. But, a powderpost beetle is more interested in starch than sugar and I've certainly had them riddle maple as well. They can convert the starch to energy, so from that viewpoint I've decided that timing might not be so critical to me, it seems if there is food, someone evolved to eat it.

The minor variations in moisture content are free water, the easy moisture to remove. I can't see that really affecting drying time.

You mention timing of the harvest relating to strengths, now that is of interest. Do you know more?

Hello,

This is a voice I have missed as of late. Glad you regained access.

Greetings,

Don Wagstaff

Relating to what you are talking about, I would hazard a guess that moon cycles could trigger certain chemical changes and biological responses within the tree, similar to the changes occurring within the maples. It would be interesting to see whether or not the sugar flow in maple tends to center around moon cycles. I would not be at all surprised if in the old day they tapped the trees when the moon was right...

The nutrient content of sap is at its lowest between the Fall Equinox and the Winter Solstice, so to prevent bug attacks trees are harvested on the days immediately preceding the new moon during that period, but not on the new moon. Cutting during this time and leaving the branches on will supposedly allow the rest of the nutrients to leach out into the branches as the tree dies.

The old wisdom apparently says that there are other resins and chemicals that are usually present in the roots that will flux around through the rest of the tree during the winter season, perhaps as a way that the tree protects itself during this time? Or perhaps merely a by-product of environmental conditions.

We also know that the makeup of the air is different in the winter than in the summer. Perhaps this has some effect?

There appears to be significant differences in carbon and calcium content in the wood (possibly among others) that does indeed revolve around moon cycles.

the Swiss to the rescue, here is a quite detailed scientific study and explanation of how and why moon phases affect timber qualities (in English) published in Switzerland:

http://www.compasnet.org/afbeeldingen/Books/Moving%20worldviews/Z%C3%BCrcher.pdf

I get from the article and other sources 2 things:

Wood harvested during the waning cycle of the moon has a higher density than wood harvested during the waxing cycle.

Trees have some biological response to moon cycles, and chemical properties change according to them. This explains how specific timing of cutting can have permanent effects on wood properties.

I also gather this:
Cut wood during the waning cycle if you want to use it to make something, it will be stronger, denser, resonate better (for instruments) etc. depending on the day.
Cut wood during the waxing cycle if you want to burn it. Wood cut during this cycle seems to store more energy, and therefore burn hotter despite the reduced density.

I suspect that the reason for cutting wood in winter cycles may be merely to stave off insect and fungus attacks. It is entirely possible that the moon cycle trends are true year round. I say this, because tropical societies also harvest building materials according to moon cycles, yet have no winter. Tropical climates are divided into dry season and wet season, rather than summer and winter.

Perhaps there is some organization out there that could study this phenomenon in detail among American tree species, and across various seasons and lunar cycles? If true, it would certainly be something for us to take into consideration.

It is said that to this day in Austria, many foresters will stamp logs with the moon cycle and zodiac sign they were cut under. I also read that in centuries past, Violin and cello makers would supervise the cutting of trees to make sure they were cut under the right moon, because that would affect the resonance properties.

I wonder if it is really the moon which is setting this schedule? Could it be something else and the moon just happens to be in sync with its 28 day cycle? Perhaps it is the Sun?

That is interesting but do be careful how far you run with that though. One mechanical property was tested, compressive strength. It and density went up with moon phase and energy value fell during that same phase... this sounds like an extractive, it could be silica for that matter. This did not measure any other mechanical properties that would be more indicative of a change in the wood itself. A chemical analysis would be interesting to see what is causing the density increase. I'm not dismissing the report by any means.

We do brand products with whatever the market wishes to buy. I'm reminded of the standing dead claim by some suppliers. I ran into a logger who told me "yup between the time when the saw exits the cut and the tree hits the ground, it's standing and it's dead".

This can be circular and frustrating and I don't want to be perceived as having my heels locked. We are learning new, or old, things every day. By the same token it is easy to hear what one wants to hear and to see proofs where they may not exist, healthy skepticism is warranted, this is slower but tends to reveal the truths, which is in the end what we want to get to.

This is a link to book 2 of Vitruvius, a contemporary of Julius Caeser, roughly the time of Christ, scroll down to chapter 9;
http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Vitruvius/2*.html

Don, I've enjoyed your postings as well. My wife's family is from NL, I've followed your posts with a bit of special interest.

the moon has 5 different months, none of them are 28 days.

The progression of lunar cycles is 29.53059 days. That is the time from one new moon to another.

the other 4 months are around 27.5 days, and have to do with the moons orbit around the earth.

moon cycles are caused by the fact that the moon wobbles in its orbit. the moon is literally closer to the earth during the full moon, and occupies more space in the sky.

Old time wisdom has to do with the moon's progression through certain constellations and across certain stars, and its phases during those times. I suspect that this has more to do with establishing a point of reference to measure from than thinking that the stars hold sway over the earth.

The moon wobbles in its orbit, and at the same time it rotates around the earth. The cycle of its wobble, it's orbit, and its day are more or less the same, which means that the same side of the moon is always facing the earth.

Thanks for the Vitrivius link! I've come across references to him many times, and have thought I ought to read his works. This is a very helpful resource for me!

Hello,

Metering, measuring, quantifying, it all reveals a potential pitfall as I see it where wood becomes equivalent to cement or steel or fiberglass, more a sum of its constituents. There are plenty of valid reasons for felling and working wood under particular seasonal conditions that have nothing to do with speculation and myths and superstition. Which is not to say that there is nothing to the story of Odin giving breath to an elm tree and an ash tree to create our first human ancestors.

While not discounting meter reading altogether, I do wonder exactly what those numbers are saying and even more so what is done with those numbers. Could it be a way of avoiding real knowledge of the wood we use and how it relates to conditions where we are? At best this metering can help with what should be the intent of getting to know and appreciate wood rather than the rationale for beginning to chop a mortice.

Greetings,

Don Wagstaff

The closer wood is to the equilibrium moisture content the less it will move in service.

My first experience with metering wood was in cabinet and furniture work. Moisture content was critical to delivering a stable product. For instance glueing panel stock that was too green and then surfacing it led to unsightly gluelines or failures. Our suppliers had contracted to deliver wood at a specified moisture content, the meter was used to verify that the wood was suitable for our uses and that the supplier had met the terms of the contract before we accepted the load.

I bought the meter above when I was contracting with homeowners to assemble log home packages they had purchased. A number of suppliers were advertising that their materials were dried to some specified moisture content. This then becomes part of their purchase contract. I have sat in that most uncomfortable chair when a client decided to take the supplier to court. In that situation fingers begin to be pointed in every direction. The supplier pointed his at me. Unfortunately we do not live in a perfect world, I ordered that meter, in that case it is another documentary tool just like my camera.

In the photos above, several years later, another supplier and a similar situation. I explained to the clients' what had happened, what they had paid for, what they had recieved, what the possible repercussions were and ways to handle the situation. At the end of the conversation they chose to proceed. I took pictures of the meter to document the conditions. It's been over a dozen years, those clients are happy with their house.

I think I've explained how the meter can be used as a tool to further your knowledge of wood and how drying is progressing. It is a tool but it does take an understanding of wood to be of use.

An analogy might be helpful. My wife is a fine gardener, she has a degree in horticulture and worked as an ag tech at a large university. She takes soil samples... prior to planting by the signs. One does not exclude the other.

There are some things I've been thinking about regarding DL Bahler's paper. I suspected the changes were due to some form of extractive, this is pure speculation based on the gist of the paper and the mechanical property they chose to test. But, think about this, one example that is given in textbooks is the similar density of Sweetgum and Mahogany. Sweetgum has shrinkage values of 5.3 radial and 10.2% tangential. Mahogany, at the same density has shrinkage values of 3.7 & 5.1%... only about half the shrinkage of Sweetgum. The difference? Mahogany is loaded with extractives. These "bulk" the cells and prevent the fibers from being able to move together unimpeded. Less shrinkage due to the higher extractive content makes the mahogany more stable through moisture fluctuations and less likely to check while drying. I don't know if this is on the right track from the information given, just more grist for the mill.

Hello,

Not only two examples of using the meter to pinpoint a given moisture level reading at a given time but a measurement of the reputability of two unscrupulous lumber dealers too. In fact, that second point is what I understood the two stories illustrated best to be honest.

Another use of a moisture meter that I can think of is a way of measuring patience. Do you have the patience to wait for that meter reading to get down there? I don't at all make light of the use of these meters and like I said up there don't discount them, just offer my perspective. I know a guy in France, a real campagnon, done the tour de France, the whole bit. I visited his yard full of oak mostly, all black and creviced some of it hundreds of years old. I'm pretty sure he has a moisture meter too. Clearly they serve some purpose and are popular, the one Don P pictured even looks like one of good quality. A lot would not be I guess. I think I even saw a moisture meter app for your iphone once, if not it's surely coming soon.

My own way of handling wood does not include the use of meters. I bring some wood home, if I cut it standing I prefer to do it in the winter when the ground is frozen and the underbrush is low, it goes though a pretty rigorous process lasting multiple years for the most part until I'm confident it has settled down, (the ol' emc or was that e=mc2? Anyway). In this way it's more a question of living with the wood than it is of trying to dial in its condition.

Greetings,

Don Wagstaff

This may be of use;
http://www.fpl.fs.fed.us/documnts/fplrn/fplrn268.pdf

I know that at this time of year the sun hits the hill at about 4 o'clock. If I'm just going home to dinner that is sufficient. If I've told a friend that I'll take them to the airport on time, I'll take my watch.

And I got no problem with that, you run a tight schedule maybe. I haven't owned a watch for 10 years.
Now, just calibrate your watch with the sun over the next few weeks or so, and pretty soon you wont need that either.

Greetings,

Don Wagstaff

I haven't used a watch for near 10 years, also. I do have a cell phone, though. I checked it today as it was getting dark, we pushed it to 5:00, I squeezed in a french snap around 4:50, I will have to check it in better light in the morning, it looked good in the dimming light.

As for dry timber in a frame, I just don't see the need to know exactly what the moisture is. Some special cases, log buildings, cabinets, finish work and so forth. But the frame, I just enjoy working green wood, why would I wait for it to get uncomfortable to work? There is always exceptions.

Of interest, sun spot activity shows up in trees, in the form of carbon deposits, leaving a record.

From this article:
http://scienceweek.com/2004/sb041217-4.htm


4) Each model used in the reconstruction makes a step in connecting the tree-ring 14C record(2) to sunspot number using parameters that were fixed by independent measurements (direct or indirect). Carbon-14, and some other isotopes such as the beryllium isotope 10Be, are formed from the bombardment of the atmosphere by cosmic-ray particles. The 14C in the atmosphere is converted to 14CO2 and incorporated into the tree rings as they form; the year of growth can be precisely determined from dendrochronology. Production of cosmogenic isotopes is high during periods of low solar magnetic activity. But during the Sun's active phase (with high sunspot number), the more intense solar wind -- the ions streaming out from the Sun -- deflects charged particles so that fewer of them enter Earth's atmosphere.

Sun spot activity has been well known far before the 17th century. The Mayan culture documented it, in one way they used the jaguar with it's spots to represent their sun god, that was not by chance.

Sun spot activity has been low, it is going to pick up soon.
http://www.spaceweather.com/

Hi,
It is speculated, so take it for what that is worth, that this is the consequence of using green timbers:


Greetings,

Don Wagstaff

Hi Cecil,

This is the famous Chesterfield crooked spire church which is located in Chesterfield, Derbyshire, England right in the epicentre of cruck country. I used to walk past this chuch every morning on my way to work at the Bryan Donkin Company and so was privy to most of the local gossip on why this spire is crooked.

Immediate observations are that it is not only crooked but it is also spiral and it is this last observation that might be key to understanding why the spire has developed a lean.

The spire is thought to have been built just before the arrival of the black death in 1349 and lay unfinished and exposed to the elements for many years. I doubt that green timber is the primary culprit more likely the design and deformation due to eccentric loading (think reciprocal framing). We would really need to see a drawing of the spire timber work to speculate on why the spire is leaning.

This church featured on a TV programme the other evening where it was explained that students from Sheffield University are part of an ongoing monitoring project to measure out of plumb movements of the spire apex. This has already demonstrated that measurements made over the past few years indicate that the tower is still on the move.

Regards

Ken Hume

Hi,
Yeah, I only walked by this building once back in the mid 80s' when I was hitch hiking from London to Edinburgh and that's when I think I remember reading on a plaque or something about the green timbers theory. It would be interesting to see the twisted and crooked timbers from inside. Also interesting to wonder about the mindset relating to these timbers of the builders back in 1349 and what would have been done then had they a moisture meter.

Greetings,

Don Wagstaff