Lime Plaster
Calcium-hydroxide finish dating to Ancient Rome — vapor-open, alkaline, and naturally mold-suppressing.
Toxicity Screening — All Clear
This material screens clear across all seven independent toxicology authorities we use on every project.
Material Type
Mineral Wall & Ceiling Finish
Material Description
Lime plaster is one of the oldest wall finishes humans have used — Roman concrete and most pre-industrial interior walls were lime-based. Modern lime plaster is the same chemistry: calcium hydroxide (slaked lime) blended with sand and water, applied wet, and cured by absorbing atmospheric CO₂ back into calcium carbonate. The cured surface is high-pH (alkaline), which suppresses mold and bacterial growth without any added biocide. Lime plaster is vapor-open, meaning it lets the wall assembly breathe rather than trapping moisture behind gypsum drywall. EBH uses lime plaster in wet rooms, around wood-burning appliances, and where vapor-open assemblies are critical.
Composition & Origin
Health Profile — All Endpoints Clear
Severity scored 0–10 against the same 10 hazard endpoints we use for the chemical families on the avoid list. Every score is 1–2 — essentially no signal across every endpoint.
Common Forms & Brands
- American Clay Loma (with lime additive)
- Limewash Co. lime plaster
- Saint-Astier natural hydraulic lime
- Common framing: lime putty, hydrated lime, hydraulic lime, tadelakt
Why We Use It
- Alkaline pH naturally suppresses mold and bacteria
- Vapor-open — allows wall assembly to dry
- Absorbs CO₂ during cure — modest carbon sink
- Self-healing — hairline cracks close as lime continues to recarbonate
- Heat- and fire-resistant once cured
Where It Performs Best
- Interior wall and ceiling finish
- Bathroom wet-room walls (tadelakt finish)
- Fireplace surrounds and masonry stove coverings
- Vapor-open exterior renders
Building Applications for Lime Plaster
Listed alphabetically. Where in a home this material earns its keep.
Bathroom Wet-Room Walls (Tadelakt)
Decorative Interior Wall Finishes
Exterior Lime Render Coatings
Fireplace & Masonry Stove Surrounds
Interior Ceiling Finish
Lime Plaster on a Bay Area Home
We specify Lime Plaster because it survives the screening. Nothing goes into one of our homes until it clears all seven toxicology databases we check — that is what makes a toxin free home different from a home marketed as one.
If you are planning a new house or a deep remodel and you want this level of material control, that is the whole job we do. Earth Bound Homes builds in Los Gatos, San Jose, Santa Clara County and across the San Francisco Bay Area.