Kiln dried logs: what you are paying for and how to check it

Updated 3 November 2026 · Hearth & Home guides

Dry wood is the single biggest factor in how well a stove or open fire performs. Kiln dried logs cost more than fresh-cut or loosely "seasoned" timber, so it helps to know what the label means, how to test it and how to keep the wood dry once it is delivered.

What "kiln dried" actually means

Freshly felled timber is heavy with water. Depending on the species and the time of year, roughly half of its weight can be moisture. Burning it wastes energy, because the fire has to boil that water off before the wood itself will burn well. The result is a low, smoky fire, a sooty glass door and tar building up in the flue.

Seasoning is the slow way of drying wood: logs are split, stacked and left in moving air for one or two summers. Kiln drying does the same job in days, using a heated chamber with controlled airflow. A properly kiln dried log should reach a moisture content below 20%, measured on the dry basis used by most moisture meters, and it should stay there if it is stored correctly.

Air-dried wood can reach the same level, but in Ireland's damp climate it is harder to get there reliably. Wood left outdoors uncovered over a wet winter can take moisture back on, which is why a stack of "seasoned" logs is not always as dry as it looks.

Why moisture matters so much

• More heat per log. Energy that goes into driving off water is energy that does not reach the room.
• Cleaner glass and flue. Wet wood burns cool and produces more tar and creosote, which coats stove glass and builds up in the chimney. That build-up is a common cause of chimney fires.
• Less smoke. Smoke is unburnt fuel. Dry wood burns more completely and produces noticeably less of it, which matters for neighbours and for local air quality.
• Easier lighting. Dry kindling and logs catch quickly and reach a good burning temperature without fuss.

What Irish law says about wet wood

Since 31 October 2022 the Air Pollution Act 1987 (Solid Fuels) Regulations 2022 (S.I. No. 529 of 2022) have applied across the whole country. For wood, the key points are:

• Wood logs and other 100% biomass fuels sold in units of two cubic metres or less must have a moisture content below 25%.
• That limit falls to below 20% from 1 September 2026, under the amending S.I. No. 389 of 2025.
• Wood sold in larger volumes (more than two cubic metres) can be wet, but it must come with a notice explaining that it needs to be stored and seasoned before it is burned.

Producers and suppliers of solid fuel have to register with the Environmental Protection Agency, and local authorities carry out inspections. The rules apply to selling and supplying fuel; the general guidance from government is simple: burn only dry wood.

How to check a delivery yourself

A basic pin-type moisture meter costs little and takes the guesswork out of buying. To get a fair reading:

1. Pick a few logs from different parts of the load, not just the top.
2. Split each one and test the freshly exposed inner face. The outside of a log dries first, so a surface reading flatters the wood.
3. Push the pins in along the grain and take two or three readings per log.
4. Readings under 20% are what you want for a stove. Anything in the high twenties or above needs more drying time before it goes near the fire.

Other clues help too. Dry logs are noticeably lighter than wet ones of the same size, often show cracks (checks) radiating from the centre, and give a hollow knock when two are struck together rather than a dull thud. Bark tends to come away easily.

Hardwood or softwood?

Both burn well when dry. Hardwoods such as ash, beech and oak are denser, so a loaded stove burns for longer between refuelling. Ash is popular because it dries relatively quickly; oak is excellent once dry but takes longer to season. Softwoods such as spruce and larch catch fast and burn hot and quickly, which makes them good for kindling and for getting a cold stove going. Many households use a mix. The species matters far less than the moisture content.

Storing logs in an Irish climate

Kiln dried wood will reabsorb moisture if it is left exposed. A good log store does three things:

• Keeps the rain off the top, with a roof or cover that overhangs the front.
• Lets air move freely through slatted sides and an open front.
• Holds the logs off the ground on a slatted floor or pallets, away from splash-back and standing water.

Avoid wrapping logs tightly in plastic sheeting: it traps condensation. Bring a day or two of logs indoors before use so they are at room temperature when they go in the stove, but don't store large quantities right beside the appliance.

Buying sensibly

Logs are sold by many different measures: nets, bags, crates and cubic metres. A "loose" (tipped) cubic metre contains less wood than a cubic metre stacked neatly, so compare like with like. Ask the supplier what the moisture content is, how it is measured, and whether the wood is certified. In Ireland the Irish Bioenergy Association runs the Wood Fuel Quality Assurance (WFQA) scheme for wood fuel suppliers.

The older firewood page in our catalogue archive and the archived article on wood as an energy source show how long dry firewood has been recommended for stoves; prices and offers on those pages are historical.

Related guides: solid fuel regulations in Ireland, how often to sweep a chimney and stove vs open fire.

More heating guides

• Stove fans: how heat-powered fans work and whether you need one
• Stoves with a back boiler: how they work and what to check
• How often should a chimney be swept?
• Solid fuel regulations in Ireland: what changed in 2022