Same price: Kfw55 with Poroton monol. OR Kfw40 with Poroton WDVS?

Hello everyone,

the recent shock with the one house provider has settled and we have started over again. We are now quite far along and one provider has drawn our house and created several offers with different masonry types at our request. We have compared and recalculated it from a financing perspective (Kfw40 with 100k at 1.54% fixed interest).

The following assumptions: The houses are different in price, but the more expensive one gets the Kfw financing, which balances it out. The question now is:

Exactly the same house,
a) Kfw55 with Poroton (brick - d 36.5 / Thermo Plan S-8 or T-8) 36.5 monolithic

OR

b) Kfw40 with Poroton (brick - d 24.0 / Thermoplan T-14) + 18 cm Styrodur

With Kfw40, the residual debt after 10 years is 4000€ higher, which you would have recovered with an assumed 200 euro saving in annual heating costs (compared to Kfw55) within 20 years, so I would say absolutely the same price or residual debt in 10 years....
What would you choose and why? Can it be said that a Kfw40 house has a higher resale value?

Thanks and best regards!

What would you choose and why? Can one say that a KfW 40 house has a higher resale value?

In the end, it’s a matter of belief. I would choose the 40 house. Why? Better efficiency (at least on paper) and in my opinion slight advantages in resale value (I am not someone who lives a lifetime in just one property). But: They are completely different construction methods. One could say "KfW 40 is simply better" or also "KfW 40 built with ETICS uses hazardous materials and the facade constantly gets dirty." Or the sound insulation is different. There are some (partly only perceived) differences.

Hello,
if you ask me: Completely the wrong approach: Whether this house still has 4000 euros more outstanding debt in 10 years, or how big the heating cost difference is in 10 years, or whether a sack of rice falls over in China. It's all about equally important.

Much more important in my opinion is noise protection. And in this regard, the T14 with 18 cm insulation is already borderline. We have exactly that combination. It just about works, but you can definitely hear the party in the neighbor's garden through the wall.

A T8 has more the sound insulation of a tent, for me it would be a complete no-go.

Best regards,

Andreas

Much more important in my opinion is noise protection. And with the T14 with 18 cm insulation, it's already borderline. We have exactly that combination. It's just barely okay, but you can definitely hear the party in the neighbor's garden through the wall. A T8 has more the sound insulation of a tent, would be a complete no-go for me.

Good point, I was assuming similar values for sound insulation. Do I understand your statement correctly then that the T8 (here in monolithic construction) has less sound insulation than the T14 with ETICS?

Hi,

Do I understand your statement correctly that the T8 (here in the monolithic construction) has less sound insulation than the T14 in the ETICS?

Correct. And significantly so. Unless you are talking about the T8 filled with mineral wool. Check the websites of the potential brick manufacturer. There you can find data sheets that also include the sound insulation value.

Best regards,

Andreas

Hi, Correct. And clearly so. Unless you are talking about the T8 filled with mineral wool. Go to the potential brick manufacturer's pages. There you can find data sheets that also include the sound insulation value. Best regards, Andreas

Already done in the meantime ;) I don't know how much 5 dB make, but the difference is there. On the left the T8, on the right the T14 Also recognizable by the bulk density of 0.6 and 0.7 respectively