Moisture sealing under the base in earth formwork

Hello originally I had planned to install perimeter insulation made of XPS below the base on a bitumen thick coating. I also wanted to insulate the base with XPS (ribbed plaster carrier board) A studded membrane was then supposed to be applied to the "smooth" surface for water drainage Now I saw today that the foundations are executed in earth shuttering construction. So the thickness varies greatly. Below the base there is now a very uneven surface that I probably cannot cover with Styrodur. How can I now achieve the planned sealing and insulation there? Or is a corresponding treatment below the base not necessary?

Hi,

I once heard about insulation that can be injected; it’s little beads like the ones used in raised floors. Unfortunately, I don’t remember what it’s called.

Daniel

Hello, I assume that you want to build the house on a slab foundation without a basement. If everything is carried out professionally, you do not need to apply any moisture barriers or insulation to the strip foundations at all. Barriers are always laid at every new layer (slab, insulation, screed). If it is not already being done, I would recommend you cover the slab with bituminous waterproofing membranes. It will certainly be cheaper than excavating the entire foundation from both sides and then insulating and insulating it. The benefit would be zero and the costs immense.

Regards Thommi

Then I am a little relieved. The base is only 30cm high and will later be 20cm free in some places. The insulation board then only goes 10cm into the ground. I have something in mind that it should go 50cm deep.

I need to check if a moisture barrier is also installed there. Tomorrow the concrete for the slab will come first.

Thanks Thommi