Sealing membrane on the floor slab

Hello forum,

we are currently renovating an old building from the 70s and have completely gutted everything. On the floor slab, 60 mm Kingspan foil-faced insulation is to be installed, and then the underfloor heating on top.

Is it sensible/necessary to lay a sealing membrane (e.g. Börner Erika) on the floor slab?
If yes, should it also be extended up the wall?
Does the edge insulation strip of the underfloor heating go before or after this?

Thank you very much for your answers.

It definitely makes sense, but even more so if you can connect the wall sealing membrane to it. That probably won't be possible in this case.

Always pull it up along the wall, theoretically up to the top edge of the finished floor. Also under any entrance doors or floor-to-ceiling windows (under the floor entry profiles, up to the outer edge of the floor slab). However, pulling it up along the wall is always a bit tricky to do with the membrane itself – I used a different system where you can then stick a connection strip to the wall and membrane. It is much easier to handle.

Edge insulation strips always come afterward; they belong in the layer above the insulation so that you can also seal the gap with them (with the usually self-adhesive foil on the edge insulation strip).

If you want, I have at least 2 Erika membranes untouched, I can give them to you (for pick-up) if it helps you. It depends on where you are in TH (we are in West Saxony).

Hello Harakiri,
thank you very much for the detailed answer.

The walls are already all plastered. Should I apply bitumen thick coating to the wall connection area afterwards so that the sealing membrane adheres better?
I live in Erfurt. I need exactly 2 sheets.

With plaster already on it is not quite ideal, theoretically moisture can then be drawn up behind the sealing by capillary action. But if the house has not had extreme moisture problems in the past, this should rather remain a theoretical problem.

As mentioned before, I would rather work with connection tape, and then fold it in the middle and stick it both to the wall and to the horizontal sealing membrane. This is also available from Börner as EriKa connection tape – you will probably need it anyway because the butt joints of the membranes must be glued with it. I would then also stay within the system and apply Böcoplast PM on the plaster as an adhesion.

The two EriKa membranes are available – they are already 2 years old, but I think/hope they are not affected by that. They have always been stored indoors. Let me know if you want to pick them up.