ᐅ KfW 55 aerated concrete construction without additional insulation

Hello everyone,

We are currently building a KfW55 house. It is constructed using 36cm (14 inch) aerated concrete blocks without any additional insulation.

We have a ground-source heat pump installed.

Every tradesperson who visits is surprised to hear there is no insulation. When I mention KfW55, nobody believes it.

I have repeatedly requested the KfW55 certification from the builder, but I am being completely ignored...

Is this even possible?
What can I do?

Thank you!
ILWJ

Then your contracting party must deliver that as well.

Hello,

ILWJ schrieb:
........if I then mention KFW55, no one believes me.

The concerns may well be justified!

ILWJ schrieb:
........I have repeatedly requested the KFW55 confirmation from the developer, but I am being completely ignored here...

Not a good sign. The general contractor/main contractor probably fears that an external expert might uncover an incorrect or manipulated invoice!
What many homeowners unfortunately do not know is that they are responsible for compliance with the Energy Saving Ordinance or KfW standards in relations with third parties, not the contractor’s agent!

ILWJ schrieb:
....What can I do?

Involve an external expert in good time! Further demands to the general contractor/main contractor are better avoided until the facts are clarified!

Best regards.

At the latest, when you submit the application to the KfW, an expert report must be prepared by an engineer. However, as mentioned above, this can of course also be just a clever calculation...

Hello,

ILWJ schrieb:

we are currently building a KFW55 house.
It was built with 36cm (14 inches) aerated concrete blocks without additional insulation. We are using a brine-ground source heat pump.

This also means that your construction project must be supervised by an independent expert with documented proof.

ILWJ schrieb:

Every tradesperson who visits here is really shocked when they hear there is no insulation,
and if I then say KFW55, nobody believes me.

Besides filled hollow clay bricks, it is also possible to build a KFW 55 energy-efficient house using 36.5cm (14.5 inches) aerated concrete blocks; the lambda value of the blocks used is different from that of a KFW 70 house. So expect some skepticism if the requirements for KFW 55 are formally guaranteed in the construction contract.

ILWJ schrieb:

I have repeatedly requested the KFW55 certificate from the builder, but I am being completely ignored...

You will only receive the final certification once the single-family house is completed. Until then, a preliminary confirmation should be provided — also necessary for applying for KFW funding.

Have you applied for any subsidies?

Regards, Bauexperte

Take a look at Ytong's website. The new aerated concrete block with a lambda value of 0.07 has surpassed the KfW 55 requirements at 36.5cm (14.4 inches)...