How much firewood do you need for 80–120 m²? Here’s how to make it last all winter.

Between the cosy appeal of a roaring fire and the reality of meeting your heating needs, there is often a sizeable gap. If you want to heat a home of 80 to 120 m² mainly with wood, it helps to know in advance how many stacked cubic metres (m³) or loose cubic metres (m³) of firewood you’re realistically going to need. In practice, the range runs from just a few stacked cubic metres to roughly double that amount - depending on the stove, the insulation and where you live.

What your real wood requirement depends on

The seemingly straightforward question, “How many stacked cubic metres do I need?” doesn’t have a single standard answer. Several factors work together:

• Floor area: 80 m² needs noticeably less energy than 120 m² - obvious, but often underestimated.
• Insulation: Well-insulated homes keep heat in; poorly insulated ones lose it constantly through walls, windows and the roof.
• Heating appliance: A modern wood-burning stove versus an open fireplace - the difference in consumption is huge.
• Region and climate: In cooler upland areas the stove runs far longer than in milder regions.
• Wood species and quality: Hardwood provides more usable heat per stacked cubic metre than soft conifer wood.
• Heating habits: Keeping rooms at 20 °C versus 24 °C makes a noticeable difference over several months.

"If you want to plan your wood requirement properly, you need to look at at least the floor area, insulation standard, stove type and wood species."

Typical consumption ranges by appliance type

The biggest lever is the appliance’s efficiency. A modern stove extracts far more heat from the same amount of wood than an open fireplace.

Modern high-efficiency wood-burning stove (firewood for 80–120 m²)

A current stove with a high efficiency rating (often over 75%) is a solid option for many detached houses:

• about 80 m², well insulated: roughly 3–4 stacked cubic metres per heating season
• 100 m², average insulation: about 4–6 stacked cubic metres
• 120 m², decent insulation: usually 5–7 stacked cubic metres

If you only use the stove as supplementary heat alongside a gas boiler or heat pump, you’ll need significantly less.

Inset fire (stove insert) or closed fireplace

A closed fireplace insert typically sits between a classic stove and an open fireplace in terms of efficiency. Consumption rises noticeably:

• about 80 m², moderately insulated: around 5–7 stacked cubic metres
• 100 m²: roughly 6–8 stacked cubic metres
• 120 m², less well insulated: 7–9 stacked cubic metres

Open fireplace as the main heat source - an expensive luxury

An open fireplace looks great, but it’s a poor heater in energy terms. A large share of the heat disappears straight up the chimney:

• 80 m², poor insulation: often 10–12 stacked cubic metres or more
• 100 m²: approximately 12–15 stacked cubic metres

"If you’re serious about heating with wood, choose a closed stove with a high efficiency rating - open fireplaces are genuine wood guzzlers."

Insulation is decisive: same space, half the consumption

The state of the building envelope determines whether warmth stays indoors or, quite literally, goes out of the window. Here are two examples for roughly 100 m² with a modern wood-burning stove:

• Well-insulated home (new windows, insulated roof, no draughts): 4–6 stacked cubic metres
• Older property without energy improvements: easily 8–10 stacked cubic metres for the same perceived comfort

So if it feels like you “have to keep topping up”, it’s not only about trying to burn less wood - it may be worth considering new windows, better-sealed doors, or extra insulation to the top floor ceiling.

Which wood species make sense for 80 to 120 m²

Not all firewood heats equally well. The energy content per stacked cubic metre varies a great deal.

Wood species	Type	Characteristic	Suitability as primary fuel
Oak	Hardwood broadleaf	Very high density, long-lasting embers	Very good
Beech	Hardwood broadleaf	Good flame pattern, plenty of heat	Very good
Ash, hornbeam	Hardwood broadleaf	Similar to beech, high heat output	Very good
Birch	Medium-hard	Faster flame, pleasant smell	Good, better as a mix
Spruce, fir	Conifer softwood	Burns quickly, sparks strongly	Better as kindling

For an 80–120 m² home that needs reliable warmth for months, beech, oak and similar hardwoods are the best fit. They burn more slowly, deliver more energy and - thanks to cleaner combustion - are also gentler on the stove.

Why dry wood is worth its weight in gold

Moisture content matters at least as much as species. Freshly cut wood often contains 40–60% water. When burned, that water has to evaporate first - and that uses up energy.

• Recommended residual moisture: under 20%
• Required storage time: depending on species, two to three years of airy seasoning
• What happens with wood that’s too wet: poor draw, little heat, sooted viewing glass, more particulate emissions

"If you have enough storage space, using your own well-seasoned wood saves real money and noticeably improves heating performance."

How to store firewood correctly

So your winter supply doesn’t rot or go mouldy, you need a well-thought-out storage spot:

• Don’t place wood directly on the ground; use pallets or a raised base
• Leave the ends open so air can pass through
• Protect only the top with a sheet or roof; keep the sides as open as possible
• Avoid wrapping everything tightly in plastic, as it traps moisture
• Ideally order wood in spring so it has time to season further before winter

For 6 to 8 stacked cubic metres, you quickly need a fairly large storage area. If you only have a small garden or a balcony, factor that into your planning early.

So, how much wood do you actually need for 80 to 120 m²?

With typical conditions, you can derive rough guide values. Each figure below assumes wood is the main heat source during the heating season:

• 80 m², well insulated, modern stove, hardwood: about 3–5 stacked cubic metres
• 100 m², average insulation, modern stove: around 4–6 stacked cubic metres
• 120 m², decent insulation, closed stove: usually 5–7, in colder locations up to 8 stacked cubic metres
• Poorly insulated older homes of this size: depending on stove output, up to 8–10 stacked cubic metres

If it’s your first year heating with wood, it’s sensible to allow a little extra. One stacked cubic metre too many is far less stressful than having to order more in a panic in mid-January - at peak times prices often rise, and not every supplier can deliver at short notice.

Practical ways to reduce wood consumption

A few everyday habits can cut usage noticeably without leaving the flat cold:

• Don’t overheat rooms - every degree less saves energy
• Keep doors closed to rooms you rarely use
• Run the stove with full, clean air supply rather than damping it down to a “low flame”
• Match heating times to when you’re at home instead of heating constantly
• Plan regular stove servicing and chimney cleaning

If you also tackle a few simple insulation measures - replacing door seals, sealing roller shutter boxes, insulating radiator recesses - you’ll often see the benefit in the wood stack as early as the next season.

What units like stacked and loose cubic metres actually mean

When buying firewood, the units of measure often cause confusion. In brief:

• Stacked cubic metre (rm): 1 m³ of stacked logs including the air gaps between them
• Loose cubic metre (srm): 1 m³ of loosely tipped logs; more air, less wood
• Solid cubic metre (fm): 1 m³ of pure wood with no gaps

Many suppliers now sell in loose cubic metres, while older consumption figures are often given in stacked cubic metres. So if you’re comparing prices, check the unit carefully - or ask the supplier to confirm.

If you want to keep 80 to 120 m² comfortably warm with wood, an honest stock-take pays off: how good is the insulation, how efficient is the stove, and what wood can you get? With realistic assumptions, a small buffer in storage and properly seasoned fuel, winter won’t turn into a nail-biter - neither for your heating nor for your bank balance.