Expand the garage

Hello everyone

I have a question regarding the conversion of a garage.
I would like to convert the garage into a room.

My question: on one side of the garage there is a concrete wall (which doesn’t look very nice), which is cold because on the other side is the earth.

How do I best insulate this concrete wall so that it doesn’t start to sweat at some point? Is this even necessary, or should I just put plaster on it directly?

Does anyone have experience with this?

Thank you very much for your input and greetings from Switzerland

Hello Michael,

This concrete wall should - if possible - be insulated from the outside. That is complicated and expensive, after all, the soil must be removed, stored, and refilled after the insulation measure. However, this would be the safest method to make this wall into an exterior wall of a living area without permanent building damage.
One does not know whether and how this wall was sealed from the outside; if not or only insufficiently (after all, it's just a garage), one must always expect penetrating moisture; if one now insulates the wall from the inside (which is technically feasible), there is the problem that penetrating moisture is located between the interior insulation and the wall - and over time it will rot, which you will notice by smell over time and eventually also visually.

Hello Hertweck

Thank you very much for your response.
This is exactly my problem, insulating from the outside is out of the question, it would be too complicated a procedure.
I have heard that this can be prevented with a foil which is mounted directly on the concrete wall. Is that true???

Hello again,
One could seal all walls in contact with the ground from the inside, from floor to ceiling, with bitumen sheets. The bitumen sheets are welded on, and then no moisture can get through. You should do the same on the floor.
From an expert’s point of view, this wouldn’t be 100% certain, since it is assumed that the moisture blocked this way will find another route; with only one wall standing in the ground, this can be neglected more easily.

Then you would have to install a timber stud wall in front of this sealed wall, preferably fixing it only at the floor and ceiling, so that the sealing is not perforated by screws.
Timber studs about 6/12 or 8/14 (metal stud walls also work, of course), the narrow side facing the wall; insulation (fiber insulation) in between, vapor barrier/vapor retarder above that. Afterward, plasterboards can be mounted. If electrical cables are run inside the wall, make sure to tape the cable outlets vapor-tight again; also use special flush-mounted boxes designed for installation with vapor retarder foils.

If sealing sheets and vapor retarder foil are mounted precisely, i.e., tightly, this should work permanently.

Thank you very much and regards
Michael