Should My Firewood Logs Crackle When Burned? Expert Opinion
It's a question we get very often: Why do my logs crackle when burned? Is this normal? Does this mean that the logs I'm using are defective? Is it safe to continue burning such firewood?
As the UK's most trusted supplier of logs and briquettes, we at Lekto Woodfuels know more than anyone else about firewood heating. We've asked our experts to weigh in, and here's what they said.
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So what happens when firewood is exposed to heat? According to our experts, several things happen beneath the surface, many of which contribute to the crackling sound.
The crackling and popping sounds that come from the logs are caused by:
1. Moisture Turning to Steam
Even well-seasoned and kiln-dried wood contains some residual moisture. As this internal water heats up, it expands into steam that pushes through small cavities and pores in the wood. It does so with force, which produces a cracking sound.
The wetter your logs, the more crackle you'll hear. Excessive crackling can indeed be a sign of high moisture content. If your logs crackle too much, you might want to check their moisture levels using a wood moisture meter (read our expert guide on wood moisture meters).
2. Resin and Sap Expansion
Softwoods like pine contain natural resins and saps. When these substances heat, they boil rapidly, leading to very loud pops and occasional mini-explosions. This is one of the reasons why softwoods burn so quickly and erratically.
This is why Lekto Woodfuels does not sell softwood logs. Our firewood logs are made from premium hardwoods, such as oak, birch, and ash.
3. Gas Release From Combustion
Wood is made of various types of tissue, chief among them being cellulose, hemicellulose, and lignin (which acts as a binding agent in binder-free wood briquettes). As these materials break down, they can release volatile gases, which can ignite suddenly and contribute to the crackling. This is the reason even ultra-dry firewood can crackle a little bit.
Is Crackling a Bad Sign?
The short answer? It depends. Occasional pops and hisses are completely normal, especially during the early stages of burning. However, if your fire sounds like tasty popcorn in the microwave, you’re probably burning wet or improperly seasoned logs.
Here’s why that’s a problem:
- Reduced Heat Output. Water inside the wood must be evaporated before combustion can properly occur. That uses up a large portion of the energy, leaving you with less radiant heat.
- Increased Smoke and Pollution. Wet wood produces more smoke, creosote, and particulates, which not only coat your flue and glass but also pollute the air, both inside and outside your home.
- Fire Hazard. Open fires are particularly at risk. When sap or steam bursts violently, it can eject hot embers or burning fragments from your hearth, potentially damaging carpets or even causing injury.
Read our full expert article on wet wood to learn more.
How Moisture Content Affects Crackling
Moisture content is the number one factor in whether your firewood crackles excessively. Logs with more than 20% moisture are considered unseasoned and are not suitable for clean indoor burning.
| Wood Type | Moisture Content | Crackling Level | Suitability for Indoor Use |
|---|---|---|---|
| Kiln-Dried Logs | < 20% | Low | ✅ Yes |
| Air-Seasoned Logs (1–2 yrs) | ~20–25% | Moderate | ⚠️ Caution |
| Green/Freshly Cut Wood | 30%+ | High | ❌ Unsafe, do not use |
Tip: Logs that are “Ready to Burn” certified will always have moisture content below 20%. Read our full article on the Ready to Burn quality standard.
Why Kiln-Dried Logs Don’t Crackle (Much)
Kiln drying is a controlled drying process that removes moisture evenly and thoroughly from the wood. Unlike air-seasoned logs, which can take up to 2 years to reach burnable quality, kiln drying delivers consistent results in days or weeks.
This means:
- Minimal moisture = less steam and fewer pops
- Longer burn time with higher temperatures
- Cleaner combustion and less tar buildup
- Safe and predictable performance every time
Kiln-dried hardwoods such as ash, oak, or birch offer a near-silent, efficient burn—perfect for wood-burning stoves, indoor fireplaces, and chimineas.
Want the Sound Without the Smoke?
Let’s be honest: the crackling sound is nice.
If you miss the nostalgic pop and snap of a traditional fire but want to enjoy the clean efficiency of kiln-dried logs, here’s a clever solution: Just stream a crackling fireplace soundtrack on your smart speaker, TV, or Spotify.
That way, you get all the ambience without compromising air quality, heat output, or safety.
Choose Kiln-Dried Firewood for a Better Burn
At Lekto, we specialise in producing Ready to Burn kiln-dried firewood designed for maximum heat and minimal fuss. All of our logs are:
- Below 20% moisture
- Responsibly sourced
- Tested for clean, safe burning
- Available in bulk, crates, or handy bags
- Delivered straight to your door
Whether you're fuelling a log burner, open hearth, pizza oven, or fire pit, our kiln-dried logs deliver steady warmth, low smoke, and minimal crackle.
Want to know more about us? Read everything you need to know about Lekto!