ᐅ Basement insulation: Ytong 36 cm, Styrodur, or XPS?

Hello everyone,
I have an appointment with my builder on April 29th, but unfortunately, the builder does not offer insulation for the basement.
Now, I would like to handle that myself.
The basement will be built with 36cm (14 inches) Ytong blocks, and half of the basement will be used as living space.

The upper floors will be built with 17.8cm (7 inches) Poroton blocks and insulated with polystyrene. (The builder will take care of the upper floors)

My question is now:
- What should I use to insulate the basement walls and at what thickness?
- Does the area under the foundation also need insulation (and if so, with what material and thickness)?

I have heard about Styrodur and XPS insulation, which one is better? And especially, what thickness and types should I use? These materials have different names that I’m not entirely familiar with.

Thanks for the help, I need to decide in a few days.

Regards,
Frico26

Frico26 schrieb:
Hello everyone,
I have an appointment with my builder on April 29th. Unfortunately, the builder does not offer insulation for the basement.
I would now like to handle it myself.
The basement will be built with 36cm (14 inches) Ytong blocks, half of the basement will be used as living space.

The upper floors will be built with 17.8cm (7 inches) Poroton blocks and insulated with polystyrene foam. (The upper floors will be done by the builder)

My questions are:
- What material should I use to insulate the basement walls, and what thickness?
- Does the area under the foundation also need insulation (if yes, with what material and thickness)?

I have heard about Styrodur and XPS insulation; which is better? And especially, which thickness and type should I choose? The materials have different names, which I am not fully familiar with.

Thanks for your help, I need to decide in a few days.

Regards
Frico26

PS. I don’t want to overdo the insulation, just looking for a good solution.

Frico26 schrieb:
I have an appointment with my builder on April 29th, but unfortunately the builder does not offer insulation for the basement.

He’s building your basement but doesn’t offer insulation? 😕
What’s up with that? 😕

Frico26 schrieb:
The basement will be built with 36cm (14 inch) Ytong blocks, half of the basement will be used as living space.

If you have habitable rooms in the basement, you naturally have to meet certain regulations – energy saving regulations / building energy codes. That means there must be some kind of thermal protection certificate for your house, showing exactly how the building components need to be insulated.

Frico26 schrieb:

I have heard about Styrodur and XPS

Styrodur is XPS (extruded polystyrene rigid foam).
What’s important is that the insulation meets the required standards—energy efficiency, building physics, and structural stability.

Best regards