Hello,
We have an upcoming final inspection for our newly built prefabricated single-family house, which includes a ground floor, upper floor, and a heated basement (everything is supposed to meet the KfW55 energy efficiency standard). The basement is made of concrete (20 cm thick) and is built into a hillside, with about 50% of it below ground level. It has 12 cm (5 inches) of insulation under the slab and 10 cm (4 inches) of perimeter insulation on the exterior walls. However, even before finishing the interior, it is noticeably colder down there compared to the other floors.
My question is: Is this insulation really sufficient for a KfW55 standard basement, especially considering the basement has underfloor heating?
Thank you in advance for any advice!
Marcel
We have an upcoming final inspection for our newly built prefabricated single-family house, which includes a ground floor, upper floor, and a heated basement (everything is supposed to meet the KfW55 energy efficiency standard). The basement is made of concrete (20 cm thick) and is built into a hillside, with about 50% of it below ground level. It has 12 cm (5 inches) of insulation under the slab and 10 cm (4 inches) of perimeter insulation on the exterior walls. However, even before finishing the interior, it is noticeably colder down there compared to the other floors.
My question is: Is this insulation really sufficient for a KfW55 standard basement, especially considering the basement has underfloor heating?
Thank you in advance for any advice!
Marcel
KFW55: This requires calculations. You can’t really say this in general terms. The basement is not considered in isolation, but the whole house. Just for your information: Kfw55 certification also requires construction supervision by an expert (including documentation). If you didn’t do this during the basement construction, it will already be very difficult to get this confirmed!
Wastl schrieb:
KFW55: You need to do the calculations.... That might be a bit too late. Additionally, many tend to forget the equivalence proof for the thermal insulation standard.
Best regards.
However, you can already tell (before finishing) that it is significantly colder there than on the other floors.Oh no, really!
Is the basement actually cooler in summer than the attic? That has to be a defect!
My question: Is this insulation REALLY sufficient for a KfW55 basement?You probably didn’t buy a KfW55 basement alone, but a KfW55 house... So it depends on how the entire house is insulated overall.
It is quite normal that the basement is not insulated to the same thicknesses as the above-ground part, since the outside temperatures are very different. In the soil, you never have temperatures of -10°C or -20°C (14°F or -4°F)... so heat losses through the basement walls are correspondingly lower, even if the insulation is thinner.
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