Wood Moisture Content - 18-20% Spruce/Pine

[Pete16]

Hey guys. I'm looking for some thoughts on the moisture content in my spruce/pine mix that I burn. I'm concerned its too high and I can't get it much below 20%. I have about two cords stored in an open faced shed (no picture). Its been in that shed for about 1.5 years, split and stacked neatly. From that shed, I stack it on my back deck to bring in to my house in the winter.

The wood at the back deck as shown in the picture sat in the shed for 1.5 years, and has been sitting on the deck now all summer baking in the sun daily. The picture is from the morning, but this back deck is south west facing and gets really really hot (the picture is from first thing in the morning so its in the shade, but normally its absolutely cooking back there). I tested a few of my splits and am still seeing anywhere from mid 18% to 19.5%. I'm sure if I freshly split one of the splits, it would be right around 20% or even 20.5%.

I live in central/western Alberta Canada where we don't have a lot of moisture in the air like you would on the coast or anything like that. Is spruce/pine just relegated to hovering around 20%? Is my moisture meter not functioning correctly? Am I doing something wrong? Appreciate any insight or thoughts.

 

[stoveliker]

I think your moisture meter is not functioning correctly.
I'd think spruce should be far lower after 2 years out of the rain, of which at least a few months in an oven.

Most operator/measurement mistakes made with a moisture meter lead to artificially low moisture content readings, not higher ones.

Even then, 20% is (just) okay for modern stoves. Folks say 15-20%. I'd burn it.

 

[Pete16]

I think your moisture meter is not functioning correctly.
I'd think spruce should be far lower after 2 years out of the rain, of which at least a few months in an oven.

Most operator/measurement mistakes made with a moisture meter lead to artificially low moisture content readings, not higher ones.

Even then, 20% is (just) okay for modern stoves. Folks say 15-20%. I'd burn it.

Appreciate the feedback. I posted this same thing on Reddit in the r/woodstoving section and most agreed with you that my moisture meter may be off. It was a $25 meter from amazon likely chinese made. I'll be buying a new one that is more reputable. Appreciate any advice on brands/types of moisture meters people like. Thanks.

 

[stoveliker]

I have this one, presumably Chinese made too.

Amazon.com

General tools MMD4E.
Works for me. But cheap ones have a higher probability of getting a dud.
On the other hand, it's low technology (just measuring an electrical resistance, and having an internal table to convert to moisture content - hence mistakes in measuring lead to larger resistances (pins not pushed in enough etc.) and lower moisture readings).

Note that if your wood is 95 degrees, the reading will be higher than it should be, because the calibration is for 70 degrees or so.
So if your home is a nice 70-ish, put two pieces inside for a day, then resplit them and measure on the newly exposed internal surface.
That's the only way to get a higher reading (unless the wood is wet from rain, shorting the pins).
Frozen wood will give you artificially lower readings, so a similar warm up inside is needed before splitting and measuring.

 

[Pete16]

I have this one, presumably Chinese made too.

Amazon.com

General tools MMD4E.
Works for me. But cheap ones have a higher probability of getting a dud.
On the other hand, it's low technology (just measuring an electrical resistance, and having an internal table to convert to moisture content - hence mistakes in measuring lead to larger resistances (pins not pushed in enough etc.) and lower moisture readings).

Note that if your wood is 95 degrees, the reading will be higher than it should be, because the calibration is for 70 degrees or so.
So if your home is a nice 70-ish, put two pieces inside for a day, then resplit them and measure on the newly exposed internal surface.
That's the only way to get a higher reading (unless the wood is wet from rain, shorting the pins).
Frozen wood will give you artificially lower readings, so a similar warm up inside is needed before splitting and measuring.

Great tips! Appreciate it.

 

[begreen]

I have the same meter. It's been reliable for me.

 

[stoveliker]

I have the same meter. It's been reliable for me.

But what's your experience regarding MC (in a worse climate, I think - i.e. more humid than the continental Alberta summers) in drying spruce for 2 years?
My (pitch) pine here gets below 20% in one year - in a relatively humid (but warm) summer near the coast. (As in 1/2 a mile from salt water.)

 

[begreen]

I agree with you. It's likely very well seasoned at this point. We get split green fir in April and it's very dry by October. In this dry year, it's below 20% by now. It settles down in the 15-17% range by the time we are burning. If the spruce is from high altitudes, it will be denser than lowland Doug Fir, but it should be dry by now.

Bang some splits together. If they ring like a baseball bat, the wood is dry. If they thunk when banged together, then the wood may still be damp inside.

 

[Ctwoodtick]

Could be a dud moisture meter. The wood looks like it’s been out of the moisture, nice and clean. I’ll bet that in the stove it will perform great. Maybe grab another cheap moisture meter of different brand and check it out. Definitely test on fresh split though. Otherwise, the reading isn’t valid.

 

[ScottLewis]

Yes, bring a few inside for 24 hours, split, and test again.

 

[Pete16]

I agree with you. It's likely very well seasoned at this point. We get split green fir in April and it's very dry by October. In this dry year, it's below 20% by now. It settles down in the 15-17% range by the time we are burning. If the spruce is from high altitudes, it will be denser than lowland Doug Fir, but it should be dry by now.

Bang some splits together. If they ring like a baseball bat, the wood is dry. If they thunk when banged together, then the wood may still be damp inside.

Yeah totally. When I bang them together, they sound like a couple ball bats hitting each other. Alternatively, I cut down some poplar that was leaning at a 45 degree angle across my driveway about a month ago. I cut and split it for some camp fire wood and there is a distinguishable "thud" sound when smacking them together. Definitely still wet.

 

[Pete16]

Could be a dud moisture meter. The wood looks like it’s been out of the moisture, nice and clean. I’ll bet that in the stove it will perform great. Maybe grab another cheap moisture meter of different brand and check it out. Definitely test on fresh split though. Otherwise, the reading isn’t valid.

Yeah, I think so. Im away from home for two weeks for work, but I'm going to be picking up that same moisture meter Stoveliker has, bring some wood inside for a day or two, split, and retest.

 

[stoveliker]

Given all of the above, I would say it's not needed to retest. The wood is almost certainly good.
If you always have spruce (and the weather of your past two years was not crazy better for drying than normal), then I think you're just fine.

Of course you can buy another meter and test. For me experimentation, real data rather than "it sounds good" (or trustworthy advice from random folks on the internet ;-) ) is always fun and good.
So you can, but imo you don't need to get another moisture meter if your methods and species don't change.

 

[Pete16]

Given all of the above, I would say it's not needed to retest. The wood is almost certainly good.
If you always have spruce (and the weather of your past two years was not crazy better for drying than normal), then I think you're just fine.

Of course you can buy another meter and test. For me experimentation, real data rather than "it sounds good" (or trustworthy advice from random folks on the internet ;-) ) is always fun and good.
So you can, but imo you don't need to get another moisture meter if your methods and species don't change.

Appreciate it, yeah, I think I'm likely totally fine. Still going to grab a new meter though, mostly because I enjoy the process of harvesting, splitting, stacking, storing, and finally burning. Maybe I'm strange, but I feel like the meter gives me that final confirmation that I'm doing it all properly. 👍

 

[stoveliker]

Not strange!

 

[Ctwoodtick]

Although I’ve really subscribed to moisture meters being the main method of figuring out how dry wood is, I found the most reliable visual indicator of dry Wood is having bark at shows at least a smidge of separation from the Wood itself. That said, I literally have some wood that has been in the woodshed and dry for eight years in which the bark has NOT separated from the Wood at all, so nothing is 100% I suppose.
But in your case, if I was seeing at least some bark separation on maybe a quarter of the firewood, I would consider it a done deal that the wood was completely ready for burning.

 

[stoveliker]

That separation probably depends on species too

 

[Ctwoodtick]

That separation probably depends on species too

Good point. Some of my eight-year-old seasoned wood is ironwood, and that shows literally no bark separation whatsoever. I even made some coffee table coasters from it, which has been indoors for a long time and that Two has no separation of the bark.
I’m not sure how much separation will come from the spruce that the OP has. If it’s any comparison, I have a good amount of white pine in which I do see bark separation occurring from the more seasoned stuff.