Hygroscopic natural finishes (clay plaster, exposed wood)

Materials that absorb and release moisture, buffering indoor humidity swings passively.

Cost

Low

Upkeep

Occasional

Lifespan

Matches wall finish lifespan; clay plaster commonly lasts decades and can be repaired/re-plastered locally rather than replaced wholesale

Embodied carbon

Low

Space / material use

Low

Output timing

Continuous process

Skill to repair

Basic

Note: Cost, carbon and footprint are rated against the other options for this same need, not in absolute terms.

Inputs

none

Outputs

none

Sources

• General natural-plaster industry/practitioner durability consensus

What this page does not tell you

No sizing or quantities: how much a technique yields, and how much a household needs, both depend on the build and the people, so the catalogue compares options rather than dimensioning them. It carries no bill of materials and no build sequence, and it is written for an oceanic, clay-soil climate (Normandy, France). Regulatory notes are indicative and need confirming locally.