Most firewood suppliers only sell one of the two, so their answer is decided before you ask. We sell both. Here is how they actually differ, what each costs, and which is right for how you burn.
It all comes down to moisture, not marketing
Freshly felled wood is roughly half water by weight. Burn it and most of the energy goes into boiling that water off instead of heating your room. That is why wet logs hiss, smoke, blacken the glass and disappoint. Everything else in this argument is a footnote to that one fact.
Kiln dried means the wood has been through a controlled drying process and comes out reliably under 20% moisture. Every log in the load is dry, not just the ones that happened to sit on top of the stack.
Seasoned means it has been cut, split, stacked and air dried. In a British climate, done properly and given long enough, that gets you to somewhere around 25%. Done badly, it gets you to whatever the weather allowed.
The number that matters
Under 20% is dry enough to carry the Ready to Burn mark. Between 20% and 25% is a good fire if you handle it well. Above 25% and you are heating the air outside your chimney.
What kiln dried actually gets you
Consistency, mostly. That is worth more than people expect.
• It lights first time. No coaxing, no second firelighter, no opening the door to poke at it
• It gets a cold stove up to temperature quickly, which matters on a February evening when the room is cold and you want heat in twenty minutes rather than an hour
• Noticeably less smoke, so less soot on the glass and less tar in the flue
• Less creosote build-up, which is the sticky residue that causes chimney fires
• It can carry the Ready to Burn mark, because that certification requires 20% or under. Ours are WS7474/00001 for logs and WS7474/00002 for kindling
• It stores badly less badly. Dry wood left somewhere imperfect deteriorates more slowly than seasoned wood does
The cost of all that is about £45 a cubic metre against our seasoned hardwood, which is roughly a 20% premium.
What seasoned gets you, and what it asks of you
A lower price, and genuinely good fires — provided you hold up your end.
Our seasoned hardwood is £180 a cubic metre against £225 for kiln dried. On a three cubic metre load that is £135 back in your pocket, which is not nothing.
The catch is storage. Seasoned wood at 25% is still drying, and where you put it decides whether it carries on drying or starts going backwards. Left in a heap on wet grass under a tarpaulin, it gets damper rather than drier, and by February you are burning something worse than you bought.
The honest version
If you have a proper log store, or a dry shed, or even a pallet against a south-facing wall with a roof over it, seasoned is excellent value. If your plan is “somewhere round the back”, buy kiln dried and spend the difference on a decent store next summer.
We also sell seasoned from two cubic metres upward rather than by the bag. That is deliberate. It comes with a note on further seasoning, and it suits somebody laying in a winter’s worth rather than topping up.
Side by side
• Moisture — Kiln dried: Under 20% · Seasoned: 25% or less
• Price per m³ — Kiln dried: £225 · Seasoned: £180
• Ready to Burn — Kiln dried: Yes — WS7474/00001 · Seasoned: No — above the 20% threshold
• Lighting — Kiln dried: First time, every time · Seasoned: Easy when stored well
• Heat output — Kiln dried: Highest · Seasoned: Very good
• Smoke and tar — Kiln dried: Least · Seasoned: A little more
• Storage needed — Kiln dried: Somewhere sheltered · Seasoned: Dry, airy, off the ground
• Sold as — Kiln dried: Loose m³, bulk bag, barrow bag · Seasoned: Loose m³, from 2m³ up
• Best for — Kiln dried: Occasional burning, no storage, late ordering · Seasoned: Regular burning, good storage, buying in summer
So which should you buy?
Answer three questions honestly and it decides itself.
Where will it live? Somewhere dry and airy with a roof and open sides → seasoned works. Nowhere obvious → kiln dried.
When are you buying? May to August, with a season to spare → seasoned. November, to burn in December → kiln dried, because seasoned will not improve in the cold and damp.
How often do you light it? Most evenings, and you have the routine → seasoned. Once a week, or a Sunday, and you want it to work without thinking → kiln dried.
What plenty of our customers actually do
Both. Seasoned for the bulk of the winter, and a bulk bag of kiln dried kept somewhere inside for the nights they want the fire lit in five minutes. It is the cheapest way to have the convenience when you need it.
A word about the word ‘seasoned’
There is no legal definition of it. Anyone can stack wood for three months, call it seasoned and sell it. That is not an accusation aimed at anyone in particular — it is simply how the word works, and it is why you should ask.
Four questions worth putting to any supplier, including us:
• What moisture percentage? A supplier who will not give you a number is telling you something
• Meter checked, or assumed? A moisture meter costs about £20. There is no excuse
• How long has it been stacked, and where? Under cover with airflow, or in a field
• What species? “Hardwood” is a category, not an answer
Ours is air dried to 25% or less, and we will meter-check a log in front of you when we deliver it. If it is ever above that, tell us and we will sort it.
What this means for what you spend
A worked example, because per-cubic-metre prices are hard to picture.
A large stove lit five evenings a week from October to March gets through roughly four and a half cubic metres. At our prices that is about £1,012 kiln dried or £810 seasoned — a difference of just over £200 across the winter, or about £1.50 an evening.
Whether that £200 is worth it depends entirely on your storage. With a good store, seasoned is the better buy and it is not close. Without one, the kiln dried will actually deliver the heat you paid for, and the seasoned may not.
The calculator on this site works it out for how you burn rather than an average.