Natural Finishes · Pacific Northwest

Earthen & lime plaster. Walls that breathe.

Natural plaster finishes for interior and exterior walls — earthen plaster, lime plaster, lime wash, and clay paint.

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The Project

Earthen & Lime Plaster

Natural plasters transform a wall. Earthen plaster — made from clay, sand, and fiber — creates a warm, matte surface that regulates humidity and feels completely different from conventional drywall or cement. Lime plaster adds durability and weather resistance, making it ideal for exterior applications. Both can be tinted with natural pigments to create a full range of earth tones. They're breathable, non-toxic, and repairable — qualities that make them the finish of choice for natural buildings and conventional buildings alike.

Earthen & Lime Plaster
Why Build One

Why choose natural plasters

Natural plasters breathe — they allow moisture vapor to move through the wall rather than trapping it, which prevents mold and rot. Earthen plasters regulate humidity naturally, absorbing moisture from the air when it's humid and releasing it when it's dry. Lime plasters are self-healing — small cracks close themselves over time as the lime continues to carbonate. Both materials are non-toxic, low-embodied-energy, and beautiful in a way that synthetic finishes simply cannot replicate.

The Process

How plastering works

Plastering is applied in layers — a scratch coat, a brown coat, and a finish coat. Each layer needs to dry before the next goes on. The finish coat is where the artistry lives: the color, the texture, the final surface quality. Earthen plasters are typically burnished or sponge-floated to a smooth or slightly textured finish. Lime plasters can be polished to a near-marble smoothness or left with more texture. Lime wash and clay paint go on last as a final color layer that can be refreshed and updated over time.

A note on timelines: any time frames mentioned here are for the active hands-on work only. Natural building happens in stages, and each stage needs time before the next one can begin — drying time, curing time, weather windows. A project that takes a few days of work can take several weeks or months from start to finish. The timeline follows the material, not the calendar. We talk through realistic expectations as part of every first conversation.

Building process
Photos

The work

Video

Earthen plaster by hand — hybrid cob natural build exterior

Earthen plaster applied by hand to the exterior of a light straw-clay infill wall. Clay, sand, and fiber worked directly onto the straw surface — each coat built up and smoothed by hand. Breathable, non-toxic, and entirely natural. A conventional frame transformed from the outside in.

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Cob Natural Builder · Portland, Oregon