What is the best way to build up the floor?

Hello everyone,

do you all still have a vapor barrier on the raw floor, something like the Katja Sprint sealing membrane from Knauf?

In our case, an Alujet foil is supposed to go directly on the XPS insulation in the basement (so without the membrane) and in the ground floor and upper floor, Styrofoam is used on the raw floor instead of XPS but also no such black membranes.

However, at the neighbors, such black membranes were glued to the raw floor (but they don't have a basement).

Can someone tell me what the difference is, should I better insist that such membranes are installed? What do you think about installing/gluing it yourself?

We are building without a basement and have exactly this so-called "Katja Sprint" vapor barrier on the raw concrete floor. We were told that this vapor barrier is supposed to prevent rising residual moisture from the concrete slab.

But then it would actually be mandatory, right?

I wish someone would just do what is standard on my house once....(-:

No idea if that is standard, but what is ever standard when building a house?

The bottom-most base plate / floor slab must be sealed to prevent moisture from the ground from penetrating into the floor structure. Conversely, intermediate ceilings do not need to be sealed. Whether the Alujet foil is suitable for this, I do not know. There are countless different types of Alujet. Whether it is allowed to lay it directly on the raw concrete, or if laying it on the XPS panels is also permitted, I do not know. I myself would prefer to have it under the XPS panels.

Ok then I have already understood that you only have to do it on the floor slab, not the ground floor and upper floor in my case....(-:

This time I just want to prevent it from being done again the way someone thinks they always do it, like with the roof, and then I’m left standing again...

If I approach it with clear common sense, I wouldn’t want to have water on the XPS boards either if it can be avoided, and therefore the sealing (whether Katja or Alujet) also in front of it