What are "Carreaux de Platre"?

This is a good question! And here is the answer. This is a very useful material to build walls and partition. Here we can see an old wall (made of flint - typical of the area), layer of "laine de verre" (horrid isulation material but cheap & very common), and finally the carreaux de platre. Electric wire are simply threaded through. Clever thing. A less clever thing is to thread water or gas pipes through those. This actually was done in another area of the house. Normally you should place water or gas pipe behind the carreaux and not in. This can be dangerous if one is planting a nail or screw. The depth to the hole of the carreaux is only 2 cm....