Exterior wall for KFW 40 (+) with or without ETICS?

You see... I'm treating myself to organic meat at the counter

A little tip, when buying organic meat always ask for the proof of origin. Unfortunately, that often gets very thin... ;-)

Hi guys,

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

Rather bad. I wouldn’t build with ETICS again.
What confuses me: does the 18 cm insulation suffice for your KfW40?

According to the builder, it is enough. I also have a colleague who built KfW 40 plus with them and has the same wall construction.

You can’t really say that in general, since many parameters go into a KfW40+. I can only advise you to involve an energy consultant early on. Wall constructions can be changed with a few clicks.

I have one, he is currently calculating the offer contents first (i.e., 24 cm hollow bricks with 18 cm ETICS).

Since you want to build KfW, you need an energy consultant anyway. Only he can specify the exact requirements; everything else is mostly shooting in the dark. I would probably also rather recommend the "better" brick, and the surcharge I’ve read so far sounds quite good.

Which brick would be the better one in your opinion? That would be another question, is the surcharge reasonable? Because I’m just wondering, for 36.5 bricks it’s "only" 900 and for 42.5 directly 7000....

Let’s leave my opinions* about ETICS and KfW4711turbo aside, then from my perspective only one fundamental decision remains for you: A. You only asked for alternatives because of the surcharge or B. You feel discomfort or other aversions against ETICS (where the KfW level does not only affect the parameter wall structure and possibly correlates with a controlled residential ventilation system, where I would also leave my opinion* aside now). Then you have to find out this answer A/B yourself. Consider also my "brick mantra" when deciding on the wall construction (there is no philosopher’s stone or devil’s stone, but there is a wall structure with which the installer has the most experience and with all others there is more potential for complications). If ETICS is basically okay for you, then 4 cm more material thickness firstly really only makes a difference for the U-value and not for you, and secondly you stay with basically the same wall structure (so you do not move away from the installer’s master routine standard). In my opinion, you should only change the brick of the structural shell if the installer has roughly the same amount of experience with it (i.e., if he builds 60:40 with brick X/Y, but not 90:10). "Same" brick filled vs. unfilled is in this sense basically "unchanged," but I agree with the expert opinion to avoid double application of filling and composite insulation, as I consider that "well-meant" naively foolish.

Yes, among other things I would like to know if the surcharge is reasonable => for 36.5 bricks it is "only" 900 and for 42.5 directly 7000. Especially since the second step, applying the ETICS, is completely omitted... Aversion to ETICS "YES and NO," somehow I find the thermal bridges or the values you can quickly achieve with it awesome, on the other hand, it’s not really solid, especially since I read that you should/must renew something like that after about 30-40 years (which probably will no longer interest me then :) )

Morning,

that is an old myth and repeating it does not make it better.... For several years now, no HBCD may be added anymore, so it is no longer hazardous waste but can be normally thermally recycled. Which, by the way, happens to the vast majority of the yellow bags we used to painstakingly separate. It is all burned together with the residual waste....

If you don’t like polystyrene on the wall (and I admit, if you knock on it, it just sounds crappy) I would recommend taking a look at mineral wool. Definitely does not burn and additionally improves sound and heat protection somewhat.

Unfilled T7-10 Poroton bricks are strongly discouraged. The sound insulation is basically no better than that of a tent...

My recommendation: forget the KFW 40+ nonsense and build the house with a stable, preferably heavy brick. Either sand-lime brick or Poroton hollow brick. Then put ETICS on the front and that’s it.

Best regards,

Andreas

Is the sound insulation really that bad with 24 cm hollow bricks and 18 cm ETICS? Is it better with aerated concrete? I have also heard sand-lime bricks more frequently... You say above no unfilled T7-10 bricks but Poroton hollow bricks (is there a difference between Poroton bricks and Poroton hollow bricks?), which ones would you then recommend and which ETICS?

A little tip, always ask for the proof of origin when buying organic meat. Unfortunately, it’s often very thin there... ;-)

He is the dealer I trust :)

Is the soundproofing with 24cm hollow bricks with 18cm ETICS really that significantly poor? Is it better with aerated concrete? I have also often heard of sand-lime brick... You mentioned above no unfilled t7 - 10 bricks, but Poroton hollow bricks (is there a difference between Poroton bricks and Poroton hollow bricks?) Which ones would you then recommend and which ETICS?

The sound insulation to the outside is specified by Wienerberger for the 24cm hollow brick with 51db and is therefore excellent. It is, for example, also higher than with a T7 42.5cm filled with mineral wool (48,xdb).

How big the structure-borne sound problem is with the 24cm hollow brick I cannot assess.

ETICS made of Neopor/plastic only burns when exposed to air. So windows explode, plaster flakes off, flames break through, after about 20 minutes the facade is burning. If everything is installed properly. If it burns that strongly, the question is what is left of the hut, regardless of the material.

Allegedly, the first ETICS made of plastic has been sticking to the house for 50 years without problems.

Recycling is being worked on. Sounds good in theory, but wastewater, energy, etc. The future will show. I find it hard to imagine that stones, in 80 or 100 years, will simply end up in the landfill.

Nails for garlands and such work. Allegedly, special dowels and screws work for lamps, mailboxes, and such. Ex-neighbor is not satisfied. During construction, firmer material can be attached at the lamp outlet.

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

Which stone would be better in your opinion? That would be another question, is the surcharge acceptable? Because I wonder, for 36.5 stones it's "only" 900 and for 42.5 directly 7000....

I don't have a favorite stone. I take the stone that fits best in the collaboration between energy consulting and the construction company for the house. I can't say how the surcharge comes about. Ultimately, the energy consultant names the different possibilities for adjustment and you decide whether you invest it in "thicker" stones, "better" windows, roof, facade, etc. For us, it will rather be roof, facade, and floor slab, but that also depends on the respective costs since I might get some materials quite cheaply. So, I am of the opinion that you won't live differently in the house if you choose a different stone, as long as you don't have particularly noteworthy circumstances like excessive street noise, etc. I would also question this €7,000 step and then just leave it and possibly invest in windows or roof insulation instead. For example, we chose an over-rafter insulation and the roof will be insulated really thick.