ᐅ Exterior Wall for KfW 40 (+) Standard: With or Without External Thermal Insulation Composite System (ETICS)?

ypg schrieb:

See... I’m treating myself to organic meat from the counter now

A quick tip: when buying organic meat, always ask for the proof of origin. Unfortunately, that’s often where things get a bit shaky… ;-)

Hi everyone,

thanks for the many replies, I was working all day and am just now reading through your opinions! Many thanks for that!!

ypg schrieb:

Rather bad. I wouldn’t build again with ETICS (external thermal insulation composite system).
What puzzles me: is 18cm (7 inches) insulation really enough for your KfW40 standard?

According to the builder, it is sufficient. I also have a colleague who built to KfW40 plus with the same wall structure.

parcus schrieb:

You can’t really say that in general, because many parameters influence KfW40+. I can only advise involving an energy consultant early on. Wall constructions can be adjusted with just a few clicks.

I have one; he is currently calculating based on what’s included in the offer (so 24cm (9.5 inches) hollow bricks plus 18cm (7 inches) ETICS).

pagoni2020 schrieb:

@Franke86 Since you want to build to KfW standard, you need an energy consultant anyway. Only they can specify the exact requirements; everything else is mostly guesswork. I would probably also recommend a “better” brick, and the surcharge I’ve seen so far sounds reasonable.

Which “better” brick would you consider? That’s another question: is the surcharge acceptable? I’m just wondering because for 36.5cm (14.5 inches) thick bricks it’s “only” 900, but for 42.5cm (17 inches) thick bricks it’s 7000 already….

11ant schrieb:

Let’s set aside my personal views* on ETICS and the “KfW4711turbo,” then from my point of view, only one fundamental decision remains for you:
A. You are only asking about alternatives due to the extra cost, or
B. You feel discomfort or other reservations about ETICS (although the KfW level affects more than just the wall assembly and may also correlate with controlled mechanical ventilation, where we’ll also leave my personal views* aside).
This A/B answer only you can find out.

Consider also my “brick mantra” regarding wall construction decisions (there is no “wise” or “devil” brick, but there is a wall construction with which the builder has the most experience—and with all others, there is more potential for problems).
If ETICS is basically okay for you, then adding 4cm (1.5 inches) more material thickness primarily affects the U-value, not your experience, and you stay with a basically the same wall construction (so you don’t deviate from the builder’s standard practice).
In my opinion, you should only change the brick of the load-bearing shell if the builder has roughly equal experience with it (e.g., 60:40 with brick X/Y, but not 90:10).
“Same” brick filled vs. unfilled is basically “unchanged” in this sense, but I agree with experts who advise against doubling up filling and composite insulation, because I see that as a well-meant but naïve and nearly foolish approach.

Yes, I’d like to know if the surcharge is acceptable — for 36.5cm (14.5 inches) bricks it’s “only” 900, and for 42.5cm (17 inches) it’s 7000. Especially since the second step, applying ETICS, would be completely eliminated...
Dislike of ETICS: “yes and no.” On the one hand, I find the thermal bridges and the values you can quickly achieve with ETICS great, but on the other hand, it’s not truly solid construction. Also, I’ve read you need to renew it after about 30 to 40 years, which probably won’t concern me anymore 🙂

andimann schrieb:

Hi,

that’s an old myth and repeating it doesn’t make it true... For several years now, HBCD is no longer allowed to be added, so ETICS is no longer hazardous waste and can be disposed of by normal thermal treatment. By the way, that’s also what happens with most of the previously painstakingly separated yellow bag waste. It all gets incinerated with regular household waste...

If you don’t like polystyrene on the wall (and I admit, when you tap on it, it sounds bad), I’d recommend checking out mineral wool. It definitely doesn’t burn and also improves sound and heat insulation slightly.

I strongly advise against unfilled T7-10 Poroton bricks. The soundproofing is roughly no better than a tent…

My recommendation: forget the KfW40+ nonsense and build the house with a stable, preferably heavy brick—either sand-lime brick or Poroton hollow bricks. Then ETICS on top of that, and it’s all good.

Best regards,

Andreas

Is the sound insulation really that bad with 24cm (9.5 inches) hollow bricks plus 18cm (7 inches) ETICS? Is it better with aerated concrete? I’ve also often heard about sand-lime bricks... You say no unfilled T7-10 bricks but Poroton hollow bricks. Is there a difference between Poroton bricks and Poroton hollow bricks? Which ones would you recommend, and which ETICS system?

andimann schrieb:

A quick tip: always ask for proof of origin when buying organic meat. Unfortunately, that’s often quite weak... ;-)

He is the dealer I trust 🙂

Franke86 schrieb:

Is the sound insulation with 24cm (9.5 inches) hollow bricks plus 18cm (7 inches) external thermal insulation composite system (ETICS) really that bad? Is it better with aerated concrete blocks? I have also heard quite often about sand-lime bricks... You said above not unfilled T7 - 10 bricks, but Poroton hollow bricks (is there a difference between Poroton bricks and Poroton hollow bricks?) Which would you recommend then and which ETICS?

The sound insulation to the outside is specified by Wienerberger for the 24cm (9.5 inches) hollow brick at 51 dB, which is excellent. It is, for example, also higher than for a T7 42.5cm (17 inches) brick filled with mineral wool (48.x dB).

I cannot assess how significant the structure-borne sound problem is with the 24cm (9.5 inches) hollow brick.

ETICS (external thermal insulation composite systems) made from Neopor/plastic only catch fire when exposed to air. So windows may shatter, plaster peels off, flames break through, and after about 20 minutes the façade is burning—assuming everything is installed properly. If it burns that severely, the question is what remains of the house, regardless of the building material.

Supposedly, the first plastic-based ETICS have been adhering to houses without problems for 50 years.

Recycling efforts are ongoing. This sounds promising in theory, but wastewater, energy use, and other factors remain challenges. The future will tell. I find it hard to imagine that bricks will simply end up in landfill after 80 or 100 years.

Nails work for garlands and similar applications. Allegedly, special anchors and screws are effective for lights, mailboxes, and such, though a former neighbor was not satisfied. During construction, stronger material can be installed at ceiling lamp outlets.

In my opinion, it does not really matter what you choose.

Franke86 schrieb:

Which stone would you consider better? That’s another question—are you comfortable with the additional cost? Because I’m wondering, for 36.5cm (14.4 inches) stones it’s “only” 900, but for 42.5cm (16.7 inches) it jumps directly to 7,000....

I don’t have a preferred type of stone. I choose the stone that works best in collaboration between the energy consultant and the construction company for the house. I can’t say how the extra cost comes about. Ultimately, the energy consultant presents the different adjustment options, and then you decide whether to invest in “thicker” stones, “better” windows, the roof, the facade, etc.
For us, it will likely be the roof, facade, and foundation slab, but that also depends on the respective costs, since I might get some materials quite cheaply.
In my opinion, you won’t live differently in the house just because you pick a different stone, unless you have particularly notable circumstances like excessive road noise.
I would also question that €7,000 step and probably skip it, possibly investing instead in windows or roof insulation. For example, we chose above-rafter insulation and will have a very thickly insulated roof.