Inspired by natural matrix-mediated biomineralisation, we present an artificial calcification approach for wood, which predominately targets the hardly accessible nanoporous cell wall structure rather than the micron-sized void system of the cell lumina. CaCO₃ can be deposited with this method deep inside the wood structure. Mineralisation of the wood cell wall architecture with CaCO₃ offers a green alternative to conventional fire-retardant systems.