Built in 1998, Jan Sonneveld has done a great job in realising his dream, an ecologically friendly house. One of the main challenges met was the exceptionally wet summer. Due to various reasons the initial lime plaster was a complete failure. (using already hydrated lime is important) The lime stucco was completely removed and replaced with clay plaster. Since then a lot of effort has been spent finding a solution to prevent moisture penetrating the plaster in less well protected areas of the walls.

The first attempt to protect the plaster with a whey wash was a failure. In some of the more critical areas moisture levels went far over acceptable levels (40%) and most of the whey was washed off in the heavy rains. A second attempt in the summer of 1999 was much more successful. This is a short (edited) report by Martin Oehlmann on the findings:

"Surprisingly the whey-lime wash performs extraordinary well on the clay walls exposed to rough weather. Whey has been added to the lime instead of water. We tested an area by spraying it for 1 hour with a hose. There was a 0% increase of humidity measured over a period of days. Some miniscule particles of the whey-lime wash protection have been washed away most probably due to the water pressure. Therefore the end of October 1999 we will brush on a second layer on the weather side to really make sure no water penetrates the walls." Since then this unprotected wall has been given a proper roof cover.

Sadly Jan Sonneveld passed away in March 2001 after fighting cancer. Happily his pionering work is being followed up by his son, Jasper, and his son's wife, Saskia, who now occupy the home. Jasper and Saskia are now completing the dream as set out by Jan. Besides some modifications to suite the purposes of a young family they are spending a lot of effort in creating a permaculture garden.

More about the Butterfly House can be seen here on the Dutch straw bale-foundation website.