A masonry heater burns fast and at high temperature, which reduces unburnt residues and emissions. The wood must be dry — two years’ drying under a ventilated shelter — and split. The annual quantity depends on the volume heated and the insulation, never on the appliance alone.
Checked on 31/08/2026
A local fuel, on one condition
Wood is the masonry heater’s fuel for good reasons: it grows close to home, its price does not follow the energy markets, and it takes little energy to produce and transport. But none of that counts except on one condition, the only one that really matters: it must be dry.
Two years under a ventilated shelter, split
Freshly cut wood is saturated with water. Burnt as it is, it spends the fire’s energy boiling off that water, burns at low temperature, fouls the glass and the flue, and smokes. Dry wood, at 20% moisture at most, burns briskly and cleanly.
To get there: split the wood as soon as it is cut, which multiplies the evaporation surface; store it under a ventilated shelter, off the ground, never under a tarpaulin on the ground; and let it dry for two years. An inexpensive pin moisture meter tells you where a split log stands: it is the meter that decides, not the colour of the wood.
Which species
Hardwoods — oak, hornbeam, beech, ash — are the firewood par excellence: dense, they give a lot of energy per log and hold their embers. Softwoods burn fast and hot, with more resin: they are suited to lighting, not to the main load. Treated, painted or chipboard reclaimed wood is never burnt in a heater.
How much wood a year?
The quantity depends on the house, not the appliance: volume to heat, insulation, pattern of occupancy, severity of the winter. It is a figure from the study, calculated for your project, not a general promise. What the masonry heater guarantees is to get the most out of every log: a brisk fire, complete combustion, heat stored rather than lost up the flue.
The stère, the cord, the kilo
Wood is sold by the stère — one apparent cubic metre of one-metre logs —, sometimes by the cord or by the stacked cubic metre depending on the region. These volumes are deceptive: two stères of cut-down logs do not take up the same space, and above all the water is paid for at the same price as the wood. The honest measure is the mass of dry wood. When buying, ask for the species, the moisture content and the length: that is what the NF Bois de chauffage certification (French firewood standard) guarantees, where the seller has signed up to it.
Wood and the air
Burning wood releases fine particles and gases; how much depends almost entirely on how it is burnt. A brisk fire, dry wood and complete combustion divide the emissions; a smothered fire multiplies them. That is why the way a masonry heater is run — one to two bold burns a day — is also a question of clean air for the neighbourhood. The emissions figure quoted at the top of the page comes from the Austrian ecolabel, there being no French equivalent to date.
The wood a masonry heater prefers
Dry, split to the size of the firebox, in hardwoods, loaded as your appliance’s data sheet specifies. The heater manual describes loading and lighting; the page on combustion explains why a brisk fire is a clean fire.
Key point — A local resource, stable in price, low in embodied energy: properly dry wood is the natural fuel of the masonry heater.
Page reviewed on 31/08/2026 by Thermasse — stove builder and founding member of the AFPMA. These general principles of the site-built masonry heater are made specific, with figures to back them up, during your project study.