ᐅ Adding Insulation to a Prefabricated House Yourself, Affordable Polystyrene Options

Hello everyone,

My prefab home supplier is offering me a standard low-energy house KfW 70.
I have now received a price for upgrading to an insulation package for KfW 55, and I noticed that only the insulation in the roof and upper floor changes. The exterior walls are already basically at the KfW 55 standard and are not further reinforced with this package. The cost of the package is about 6000 euros.

My question to the experts is: Can I simply take the standard package and add additional insulation myself in the attic?
For example, just line the entire attic with Styrofoam since no one really accesses the roof anyway.
How do you assess this approach?

Thanks and good luck.

Hello,

VanTide schrieb:

My prefabricated house supplier offers me a standard low-energy house KfW70.

Which supplier is it? It’s odd that they don’t offer you KfW 55 as standard? This is something that this type of supplier can still use as a selling point, so I don’t quite understand why yours would not?

VanTide schrieb:

My question to the experts is: can I take the standard package and simply add extra insulation in the attic as a DIY project?

*Sigh* ... you can do many things if you have the necessary craftsmanship. However, if you need proof that the house actually meets the KfW 55 efficiency standard, the situation looks quite different in my opinion.

What kind of technology is being offered?

Kind regards from the road

Hi. The provider is Bien-Zenker. Bien-Zenker offers an air-source heat pump, which I want to support in winter with a 7 kW (9.4 hp) wood stove. I have already spoken with several families using this technology, and all were satisfied. Therefore, the question is whether it might be better to insulate more thoroughly right from the start to achieve a better efficiency (kW per m²). I am specifically concerned about ceilings and the roof.

Hello,

VanTide schrieb:

The provider is Bien-Zenker.

I am currently waiting for the documents from my clients – I hope they will be available after I return. Therefore, I cannot say much about the provider or their services at the moment.

VanTide schrieb:

They offer an air heat pump technology, which I want to support in winter with a 7 kW (9.4 hp) wood stove. I have also spoken with several families who use this technology, and all were satisfied. So the question is whether it wouldn’t be better to improve insulation right away to achieve a better performance (kW per m²). I am particularly interested in ceilings and roofs.

7 kW (9.4 hp) is quite significant – I also assume you mean an air-to-water heat pump?

If you have already spoken with the provider’s customers, why didn’t you ask them what they think about your idea or if they upgraded to KfW 55 standards? You should be able to get firsthand information here.

Best regards from the road

Bauexperte schrieb:
Hello,


I am currently waiting for my clients' documents – I hope to have them when I return. Therefore, I can’t say much about the provider or their services yet.


7 kW is quite substantial – I also assume you mean an air-to-water heat pump?

If you have already spoken with the provider’s clients, why didn’t you ask them what they think about your idea, or whether they upgraded to KfW 55? You should be able to get firsthand information there.

Best regards from the road

They said they insulated to KfW 40 but used the 2007 standard, so to speak. Since I can’t compare that, my idea was to aim for KfW 70 and then possibly improve the roof insulation later.

By the way, do you have any experience with air-to-air heat pumps combined with wood stoves?

Do you also have experience regarding soundproofing with providers like Bien-Zenker compared to solid construction houses?

Hello,

VanTide schrieb:
my prefabricated house provider offers me a standard low-energy house KfW70.
I’ve now received the price for choosing an insulation package KfW 55, and noticed that only the insulation in the roof and upper floor changes.

The two standards differ in the Qp´´ value, so not only by the Ht´ value (insulation).

VanTide schrieb:
...The question for the experts is, can I just take the standard package and add extra insulation myself in the attic? For example, just line the entire attic with polystyrene since no one will enter the roof anyway.

Unfortunately, it’s not that simple. If the insulation is sufficient, proper professional installation is required (including wind tightness, dew point issues, etc.).[/quote] So just throwing in some insulation panels won’t do!
For the additional 6,000 € you could also stay at KfW 70 and choose a brine heat pump instead of an air heat pump, with various, cost-effective heat sources. This might leave some budget while reducing consumption at the same time ;-)
But without adequate basic investigation, no precise statements can be made!
It doesn’t always make sense to blindly chase subsidies.

Best regards