Start With the Firebox, Not the Log Pile

Before you order a load of wood or pick up a saw, measure the space you are actually feeding. Take a tape measure and check the internal width of your firebox from the back brick to the inside face of the door glass. Then subtract a sensible clearance at each end — around 50mm is a good working figure — so you can close the door without scraping bark across the glass and still get air moving around the fuel.

Most UK stoves fall into a few familiar sizes. A compact 4–5kW model usually takes logs of about 25cm. Mid-sized stoves, the 5–8kW workhorses in most sitting rooms, generally want 30cm or 33cm. Bigger freestanding stoves and inset models can swallow 40cm or more, but only if you load them side to side rather than front to back. The direction matters as much as the number: a firebox that is wide but shallow will take a long log laid across, while a deep, narrow one wants shorter lengths pushed towards the back.

A log that is too long is the most common mistake. It props the door open, smokes the glass, burns unevenly and rolls forward onto the hearth when you open up. A log that is far too short is nearly as bad: it rattles around, leaves big gaps, and gives you very little control over the burn.

How Log Diameter Changes the Burn

Length is only half the equation. Diameter governs how quickly a log releases its heat, and it is worth thinking about in terms of your own wrist. A split piece between roughly 75mm and 100mm across is the sweet spot for most stoves — big enough to burn steadily, small enough to catch properly and give up its moisture.

• Thin splits, under 50mm: brilliant for kindling and reviving a dull fire, but they burn away fast and can over-fire a small stove if you pack them in.
• Medium splits, 75–100mm: the everyday fuel. Reliable, easy to stack, good control.
• Large rounds, over 125mm: slow to ignite, prone to smouldering, and usually too much for anything under about 8kW.

If a round is thicker than your forearm, split it. That single habit will do more for your stove's performance than almost anything else.

Why Splitting Matters More Than You Think

A split log exposes far more surface area than a round one of the same weight. More surface means more contact with flame and hot air, which means the wood gasifies and burns rather than sitting there steaming. The result is a hotter firebox, a cleaner burn and noticeably less smoke drifting down the garden.

Splitting also speeds up seasoning. A round of hardwood can take two years or more to dry down below 20 per cent moisture; split into quarters, the same wood might be ready in a single summer. If you buy in bulk, ask for it split rather than in rounds, or plan to spend a few hours with an axe before stacking.

Split green wood where you can — it cleaves more willingly and the pieces stack more neatly. Knotty, twisted rounds are the exception; leave those until they have dried a little and they will come apart far more easily.

Stacking Inside the Firebox

How you lay the wood in matters as much as how you cut it. Air needs to move through the fuel bed, not around a solid wall of timber.

• Load two or three splits side by side with small gaps between them, then lay the next layer across the joins.
• Keep fuel back from the glass by 50mm or so; this reduces tar staining and stops logs rolling forward.
• Leave clear space beneath the baffle plate at the top. Filling right to the roof smothers the secondary burn and wastes fuel.
• Aim to fill roughly two-thirds of the firebox height on a reload, not the whole thing.

If your fire smoulders, darkens the glass and produces a lazy, grey plume from the chimney, tight packing is often the culprit. Loosen the stack, open the air a touch and the fire will usually pick up within a few minutes.

Cutting and Storing Your Own

If you process your own wood, make yourself a measuring gauge — a stick cut to your ideal length, or a mark painted on the sawhorse. It takes seconds to check and saves endless fiddling at the stove door. Cut to the shortest sensible length for your firebox, not the longest that will just fit, as bark and knots add bulk you cannot see from the tape.

Store split wood off the ground on pallets or in crates, with the top covered and the sides open to the wind. A moisture meter is a cheap and genuinely useful tool: prod a freshly split face and look for a reading under 20 per cent, ideally nearer 15. Wood that hisses, bubbles at the end grain or refuses to light without a firelighter is not ready, whatever the calendar says.

Keep a small supply indoors in a basket or log store, but only a day or two's worth. Bringing damp wood into a warm room weeks ahead just encourages mould and takes heat out of the fire when it finally goes on.

Quick Checks When Something Feels Wrong

• Door will not shut cleanly: logs are too long. Re-cut or re-split.
• Fire smoulders and smokes: pieces too large, too tightly packed, or too damp.
• Heat disappears up the chimney: thin splits burning too fiercely in a big firebox.
• Glass blackens within an hour: fuel touching the glass, or a firebox crammed too full.
• Fire dies overnight: try a couple of larger, well-seasoned hardwood splits laid tight at the back for the last load.

Get the size right and everything else follows: an easier light, a steadier heat, cleaner glass and a chimney that stays sweeter for longer. It is a small piece of forward planning that pays you back every cold evening of the year.