Dry wood does not stay dry
This is the part nobody tells you when you buy firewood. Wood is hygroscopic — it takes moisture from the air and gives it back, continuously, for as long as it exists. A log dried to 18% in a kiln will happily climb back to 25% or worse if you leave it somewhere damp.
So the £420 you spent on a full transit of properly dried hardwood in October can be £420 of disappointing wood by January, entirely because of where it sat. It is the cheapest mistake to avoid and the most common one we see.
Rain from above, ground moisture from below, and still damp air that never moves. Wood copes with cold, wind and frost perfectly well — frost actually helps. It is standing water and stagnant air that ruin a stack.
The three rules
1. Off the ground
Ground moisture wicks straight up into the bottom layer and then sideways into the rest. A stack sitting on soil, grass or even a concrete slab will have a wet, mouldy bottom course by spring.
Pallets are the classic answer and usually free. Gravel, paving slabs, bearers, scaffold boards, a couple of fence rails — anything that gets air under the pile works. You need 50mm of clear air underneath, not much more.
2. Covered on top only
Rain needs to be kept off, so the top of the stack wants a roof: a sheet of corrugated, a lean-to, a proper log store, or a tarp weighted down over the top third and no further.
3. Open at the sides
This is the one people get wrong, and it is worth its own section below. Air has to move through the stack. Without airflow, the moisture the wood gives off has nowhere to go, and it condenses back onto the wood.
The mistake nearly everyone makes
Wrapping the whole stack in a tarp.
It is the instinctive thing to do and it is the worst thing you can do. A tarp all the way round turns the pile into a sealed box. Wood gives off moisture, the moisture cannot escape, it condenses on the inside of the tarp, runs back down into the wood, and by February you have a stack that is wetter than the day it arrived and growing something.
We have been called out to look at “bad wood” more than once and found perfectly good kiln dried logs that spent three months inside a sealed blue tarp. The wood was fine when it left us.
Cover the top and let it hang down over the top third of the sides at most. Weight it along the top rather than tucking it underneath. The stack needs to breathe from the sides even if the top is sealed.
Where to put it
| Location | Verdict | Why |
|---|---|---|
| Open-fronted log store | Best | Roof, raised floor, open front. Exactly the three rules. |
| Against a south or west wall | Very good | The wall sheds rain, the sun and prevailing wind dry it. |
| Under a lean-to or carport | Good | Roofed and airy. Keep it off the slab on bearers. |
| Garage or shed | Mixed | Dry but often still. Fine if there is any ventilation. |
| Sealed outbuilding | Poor | No airflow. The wood sweats and stays damp. |
| Under a tarp on the lawn | Worst | Ground moisture up, condensation down, no air through. |
Two practical points beyond the technical ones. First, put it somewhere you will actually walk to in the rain — the store at the bottom of the garden gets used far less than the one by the back door, and a household that cannot face the walk ends up burning whatever is nearest instead.
Second, keep a few days’ worth indoors. Bringing logs into the warm for 48 hours before burning takes the surface damp off and makes a noticeable difference to how they light.
Ton bags are craned off and set down where you point, and the bag itself keeps the worst off. Dearer per cubic metre, and the right call if the alternative is a soaking heap.
How long it keeps
Stored properly, seasoned and kiln dried hardwood is good for two to three years without meaningfully degrading. Ash and oak will sit happily for longer than that. There is no rush to burn a load through in one winter, so buying a full transit that lasts you two seasons is perfectly sensible if you have the room.
Stored badly, the same wood can be unusable in a single winter. Beech is the first to go — it rots faster than the others when it stays wet — followed by birch. Oak is the most forgiving and will tolerate poor storage longer than anything else on the list.
Signs a stack has gone wrong: white or green mould on the cut faces, bark falling off in sheets, a musty smell, and logs that feel heavier than they look. If it hisses at the ends when it burns, that is water boiling out and the storage is the culprit.
If you are drying green wood yourself rather than storing dry wood, the rules are the same but the timescales are different — see how to season firewood.