Earthen Floors: Installation and Maintenance An earthen floor is a finished interior floor made from clay, sand, aggregate and natural fibers, sealed with oils or waxes. For DIY builders, an earthen floor offers low upfront material costs, low embodied carbon(/glossary/embodied-carbon), and a breathable living surface that can add thermal mass to a passive-house or off-grid build. This guide walks through what an earthen floor is, when it makes sense, how to test and mix materials, step-by-step installation (with a video), finishes and sealers, and practical maintenance and repair routines. TL;DR: - Use a coarse base (20–50 mm) plus a fine finish (6–15 mm); expect 2–8 weeks drying for interior finishes in temperate conditions. - Test mixes on small patches (jar test + 1 sq ft patch) to check shrinkage and adhesion before committing a whole room. - Choose oil or wax finishes for breathability; avoid Portland cement stabilization unless moisture control is fixed. What is an earthen floor...