Why Moisture Content Matters More Than Anything Else

If you take one thing away from this article, let it be this: the single biggest factor in how well your fire performs is how much water is still locked inside the wood. Freshly felled timber can be 50% water or more by weight. Burn it like that and you are spending most of your heat boiling that water away rather than warming your living room. You get a sullen, smouldering fire, a glass door you can't see through, and a chimney lined with tar and creosote that is a genuine chimney fire risk.

For a log to burn cleanly and efficiently, it needs a moisture content below 20%, and ideally somewhere between 15% and 20%. Above that, you lose heat, produce far more smoke and particulates, and clog your flue. If you live in a smoke control area, you are also legally required to burn authorised fuels or use an exempt appliance, so drying your wood properly is not just good practice — it is part of staying on the right side of the rules.

What Kiln-Dried Logs Actually Are

Kiln-dried logs are stacked into large drying chambers and blasted with warm, moving air until their moisture content drops — usually to between 10% and 20%, and often closer to 15%. The process takes days rather than months, which is why the logs reach you ready to burn the moment you get them home.

You can usually spot them by feel and appearance:

• They feel noticeably light for their size.
• The bark is often loose and the ends may show small cracks.
• Two logs knocked together give a sharp, hollow crack rather than a dull thud.
• There is no sign of mould, fungus or that damp, earthy smell.

Because the moisture has already been driven off, kiln-dried logs light easily, burn hot and produce very little ash and tar. The trade-off is price: you pay a premium per load for that certainty and convenience.

The Traditional Approach: Air-Seasoned Wood

Seasoned wood is dried the old-fashioned way — split, stacked and left to the mercy of the British weather for a year or two. When it works, it works beautifully and cheaply. When it doesn't, you end up with a stack of damp logs that sulk in your stove all winter.

Timing depends heavily on species. Ash is the traditional favourite and can be ready in a single summer. Oak, however, is dense and slow, and really wants two years or more. Sycamore and birch sit somewhere in the middle. Softwoods such as pine and spruce dry quickly but burn fast, so you get through more of them.

The advantages are real: seasoned wood is often considerably cheaper per load if you buy in bulk in spring, and many households get it free or nearly free from a friendly tree surgeon. The catch is that you need somewhere genuinely dry and airy to store it, and you need the patience to plan a full year ahead.

Cost, Heat and Convenience Compared

The headline price per cubic metre usually favours seasoned wood. But price per load is not the same as price per unit of heat. You are not paying for water when you buy kiln-dried logs, so you get more usable energy from a smaller stack, and you burn fewer logs to reach the same room temperature.

• Kiln-dried: higher upfront cost, immediate use, predictable quality, less storage needed, minimal smoke and tar.
• Seasoned: lower cost per load, requires 12–24 months of forward planning, quality varies wildly, needs generous outdoor storage.

There is one important catch with kiln-dried logs: they are thirsty. Leave them out in the rain or in a damp shed and they will happily reabsorb moisture, undoing everything the kiln did. Seasoned wood, by contrast, needs continued airflow rather than a sealed box — trapping it in a closed container with no ventilation is a recipe for mould.

Which Should You Choose?

There is no single right answer, only the right answer for your setup.

Lean towards kiln-dried if you have limited storage, buy logs as you need them, want a hot fire within minutes of getting home, or live in a smoke control area where clean burning really matters. It is also the sensible choice for anyone new to a stove who wants to remove the guesswork.

Lean towards seasoned if you have a proper log store, plenty of space, and the discipline to buy next winter's supply this spring. A cheap moisture meter — you can pick one up for the price of a couple of bags of logs — takes the guesswork out of it. Split a log, push the pins into the freshly exposed face, and check the reading before you commit a whole load to the stove.

Plenty of households do both: buy seasoned wood in spring for the following winter, then top up with kiln-dried logs for the coldest snap in January when you want instant, reliable heat.

Getting the Best From Either Type

Whatever you burn, a few habits make a genuine difference. Store logs off the ground on a pallet or rack, with the bark facing up and plenty of gaps for air to move through. Cover the top against rain but leave the sides open. Bring a day's worth indoors to come up to room temperature before burning — cold logs lose heat warming themselves up.

Never burn painted, treated or varnished timber, and avoid old pallets unless you know they have not been chemically treated. Book your chimney sweep once a year, more often if you burn a lot of softwood. Get these basics right and whether your logs came from a kiln or a windy corner of the garden, your stove will reward you with a warmer home and a good deal less soot.