ᐅ External perimeter insulation of the foundation slab, risk of mold in the basement

Hi,

for our house with a basement, both builders have only included insulation on the concrete slab. An additional cost for external insulation is about 3400€ (WLG035, 10cm (4 inches)).

The basement will mostly be used for storage, while the hallway and a large room will be heated with underfloor heating. Would you recommend adding this insulation to avoid or minimize cold bridges in the corners and thereby reduce the risk of mold?

Regards,
danielh

What does your planner’s calculation say about whether this insulation measure is necessary?
They have also completed the energy saving regulation calculation and can tell you if it might actually be required.

Aside from that, I find the idea of "insulation on the concrete slab" a bit surprising.
Either the slab is insulated beneath it – or the slab is not insulated, and you try to add a few centimeters (inches) within the floor construction under the screed.
In that case, you still have thermal bridges at the wall bases and exterior walls...

-Calcium silicate brick

Hello,

danielh schrieb:
An additional cost for external insulation is about 3400€ (WLG035, 10cm (4 inches)).

If a preliminary site assessment has been carried out for the project, the extra effort can be economically evaluated. The building services technology also plays a major role. With a ground-source heat pump as the heat generator, the impact on heating energy costs will likely be minimal, whereas with a gas condensing boiler, it will be noticeably greater.
Overall, the additional financial effort is not significant, so it is definitely worth considering. In some cases, this can even eliminate the need for a usually uneconomical solar thermal system in a detached house.

Best regards

With a brine-to-water heat pump as the heat source, the impact on heating energy costs will be rather minor, whereas with a gas condensing boiler it will be significantly more noticeable.

*oops* Is the price per kWh really that different between these two options in Brandenburg?
For me, it’s roughly 1:1 😕

Can someone explain the abbreviations to me?

According to their calculations, it is not necessary for either option to achieve KfW 70. The insulation on the concrete slab is already the one you described in the floor structure beneath the screed. I also now have the exact price from the second provider.

About €2500 for the insulation and €1100 for modifying the grounding (stainless steel grounding).

Ah ok, thanks. We will be building with the LUWA heat pump.