How to measure the moisture content of firewood logs
Why is this so important?
Well, it defines the ease of burning, heat output and completeness of burn of your firewood. If you get this wrong you could cause tar in your flue. Note! It is also the law now.
It is also a requirement if you buy our low cost semi-seasoned firewood for DIY drying
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So how do we measure the moisture content.
I will start with the easiest way, and the one you should adopt.
It does require the purchase of a moisture meter, see examples here:
Once you have purchased your meter, read the manual carefully as there are often calibration instructions and different settings for different timber species.
So where on a log do you test.
This is the complicated part. Due to the way logs dry (nearly all evaporation comes from the end grain) the centre of logs will always be wetter than the outside.
Bear in mind we are trying to assess the AVERAGE moisture content. So my suggestion is that you split a log lengthways with your axe and measure from the end and the centre.
The average will be closer to the end than the centre, so consider a number 1/3 of the way from the lowest to the highest reading.
So for your logs to be ready to burn, we need the average moisture content to drop below 20% (this is a magic number where the burning properties suddenly improve dramatically and it satisfies the new burning laws). For larch this will will happen quite easily, for other species you will require better & longer storage (more sun, more wind, more time).
Here at Firewood Express we measure moisture content both with a meter and the scientific way to determine when batches are ready for release.
For the scientific way we take 10 logs for different areas of the stock. We then cut one quarter from each log, splitting them in both directions.
1. We weigh the 10 quarters.
2. We dry them in an oven at 100 deg C for 12 hours.
3. We re-weigh the batch .
The difference in weights divided by the initial weight x 100 gives the moisture content in %.
For example; 2.0kg initial weight, 1.5kg final weight. Difference = 0.5KG => 0.5/2.0 x 100 = 25%
