ᐅ Basement without additional floor covering / cleaning of the concrete slab

In our case, even with two rooms in the basement, the concrete slab was trowel-finished and nothing else was done. Compared to the bare screed, it no longer produces dust; vacuuming and mopping have shown no negative effects so far. In the utility room, we applied a concrete floor paint, which looks a bit tidier but doesn’t feel very different. The difference between mopping and sweeping the untroweled part of the slab (where there is now parquet flooring) and the trowel-finished part was huge—the trowel-finished surface is truly very, very smooth.

My report is a short-term assessment (the slab was trowel-finished in November and occupied in July).

11ant schrieb:

I have had both types in garages: one with a bare concrete floor and the other with a waterproof coating. The only difference was how puddles from melting snow behaved: in one case, it dried slowly (usually about two days until it was completely gone), and in the other, it disappeared immediately when wiped away with a squeegee.

Let's just hope the mentioned basement doesn’t get snow coming in 😀

Realistically, you want to build for 700,000.
Screed costs somewhere between 12.5-15 €/m2 (approximately $13-16 per square foot) — I would skip this without underfloor heating.
Gypsum plaster Q2 is around 10 €/m2 (about $10-11 per square foot).
I really wouldn’t try to cut corners here.

Then the basement quickly becomes a really great living space

TmMike_2 schrieb:

Then the basement quickly becomes a "very cool" living area.

Dear respondent, have you actually looked at the original question from the person asking?

"Hendrik1980" stated the following:
"Our basement is intended exclusively for laundry, storage, pantry, and a technical room. Not least for cost reasons, we are foregoing heating, insulation, and plastering or painting work here."

According to the plan, the slab serves as the structural base for rooms with secondary purposes. This means that there is no thermal insulation and, more importantly, no vapor barrier under the slab at all.

In practice, it is assumed that under a slab in direct contact with the ground, there is always a relative humidity of about 90%. The humidity in the functional rooms above is always lower. If moisture rises (and it will inevitably travel through the concrete matrix) and moistens the room above, this has no impact on the intended use.

Now, a higher standard of room usage is being requested: as a party room or a study. Such a room will be nicely heated, which accelerates moisture balancing due to the lower relative humidity.

Long story short:
A room planned for secondary use cannot simply be converted into a higher-standard living space! High humidity, with a high probability of mold growth, an unfavorable indoor climate, and cold floors are consequences the builder must accept.

Building involves accompanying aspects of building physics that must be understood when constructing—or even when acting “advisory” only.

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Good luck to "Hendrik1980": KlaRa

Hendrik1980 schrieb:

Is it possible to tile directly over BP? How thick is a screed without insulation? I’m just wondering if there might be height issues (e.g., at the stairs)?

Tiles: Apply leveling compound and a two-component primer, then tile. Possibly use decoupling mats.

Screed: 3 to 5 cm (1.2 to 2 inches).