Here is the same project of earthen plaster on woodchip/clay walls. You can see these are interior walls, and the clay plaster is still in the process of drying.
Once the walls are dry, an amazing thing about using clay plaster is that it is hygroscopic, meaning it absorbs excess moisture and releases it slowly, providing a more even moisture content in the air.
If you want to read more in depth about clay plasters, check out an article written by Philip Allen and Neil May called “Clay Plasters”. Here is an excerpt:
“Clay plasters have been used extensively in buildings in the UK and indeed all over the world, for thousands of years. Although it is not widely known, there are probably over a million buildings with clay materials in their structure in the UK, and a great many of these have clay plasters. …The point of this article is to demonstrate not only that clay plasters are important historically, deserving proper repair and preservation, but also that clay plasters are a viable and high quality material for use in standard conservation and renovation work, the extension of historic buildings, and even within modern building contexts such as for new buildings in conservation areas and elsewhere. ”