ᐅ Converting a Garage into Living Space

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), and it feels cold because there is soil on the other side.

What is the best way to insulate this concrete wall to prevent condensation over time? Is insulation necessary at all, or should I just apply a plaster directly?

Does anyone have experience with this?

Thank you very much for your input, and greetings from Switzerland

Hello Michael,

This concrete wall should ideally be insulated from the outside. Although this is complicated and costly, since the soil has to be excavated, stored, and backfilled after the insulation work, it is the safest way to convert this wall into an exterior wall of a living space without causing long-term building damage.
You cannot be sure if or how this wall was waterproofed from the outside; if it was not or only insufficiently (since it is just a garage), moisture intrusion must always be expected. If the wall were insulated from the inside (which is technically feasible), moisture entering the wall could become trapped between the interior insulation and the wall itself – over time this would cause rot, which would eventually produce odors and become visible.

Hello Hertweck

Thank you very much for your reply.
This is exactly my problem: insulating from the outside is not an option, as it would be too complicated.
I have heard that this can be prevented by using a membrane that is installed directly on the concrete wall. Is that correct???

Hello again,
You could seal all walls in contact with the ground from floor to ceiling on the inside using bitumen sheets. The bitumen sheets are torched on, so no moisture can pass through. You should do the same on the floor.
From an expert’s perspective, this is not 100% guaranteed, since it is assumed that the blocked moisture might find another path; however, this can generally be neglected if only one wall is in contact with the soil.

Next, you would need to build a timber stud wall in front of the sealed wall, preferably fixing it only at the floor and ceiling to avoid perforating the waterproofing with screws.
Use timber studs approximately 6x12 cm (2.5x5 inches) or 8x14 cm (3x6 inches) with the narrow side facing the wall; mineral wool insulation should be installed between them, followed by a vapor barrier/vapor retarder. Then you can install gypsum boards. If electrical wiring runs inside the wall, make sure to reseal the cable outlets vapor-tight using special flush-mounted boxes designed for installation with vapor retarder membranes.

If the waterproofing sheets and vapor retarder are installed precisely and sealed tightly, this system should function permanently.

Thank you and best regards
Michael