Place the wall barrier foil on the first laid masonry layer?

Hi everyone,

Is it no longer common to lay a foil on the first masonry layer? So on the floor slab comes the sanded cavity barrier [Mauersperrbahn], then the stone (KS or aerated concrete) and on the stone another foil? Or is that no longer common? If yes, why not?

Regards

That cannot be answered in a general way. It depends on the load. If the wall above the base plate is not exposed to any moisture, you do not need an additional barrier layer.

That means I would need an additional barrier layer in the wet rooms?

No. It is about moisture exposure from the outside, from the soil or through splash water. In the bathroom, etc., the sealing is done from the inside, generally and simply put, e.g. by the tiler.

Ah okay. Thanks!