ᐅ Exterior insulation system (ETICS) on 24 cm Poroton brick or alternatives?

Hello,

we are currently building a KfW70 house with about 180 m² (1,937 sq ft).
The exterior walls are made of 24 cm (9.5 inches) Poroton masonry, heating is gas plus solar for hot water.
There is no ventilation system.
The planned exterior insulation: ETICS (external thermal insulation composite system) with 20 or 24 mm (0.8 or 0.95 inches) thickness.

Now, there are some interesting programs criticizing the extensive use of ETICS, claiming it is wrong, flammable, causes moisture issues between the insulation and masonry, and so on.

That’s why we came across wood fiber insulation.
This is available, for example, from Knauf or Unger.

Our architect thinks there is no reason to deviate from ETICS.

What are your opinions on this?

einstratege schrieb:
....we are currently building a KfW70 house with about 180 m² (1940 ft²)
24 cm (9.5 inches) Poroton masonry on the exterior, heating with gas plus solar hot water
No ventilation system
Planned exterior insulation: ETICS 20 or 24 mm (0.8 or 1 inch)

I would advise against solar thermal systems and suggest taking advantage of the 15% rule, especially with gas condensing boilers, as actual consumption is always higher than the calculated heating demand. Furthermore, solar thermal systems are usually not economical in single-family homes.

einstratege schrieb:
....There are some interesting broadcasts about the insulation craze with ETICS
It would be wrong, flammable, moisture getting trapped between ETICS and masonry, and so on

What self-proclaimed "experts" sometimes claim is more than questionable.

einstratege schrieb:
....Our architect believes there is no reason to avoid ETICS.

I basically agree with the principle of separating functions in the exterior wall. However, one should then be consistent. A 17.5 cm (7 inches) structural layer of the building envelope is usually sufficient if it has the appropriate compressive strength. Additionally, it provides suitable thermal mass.

Regards

Hello,

Ok, but that was not the question. I’ve also heard that it might not really be cost-effective. However, I’m not familiar with any 15% rule.

If anyone has more opinions on ETICS (External Thermal Insulation Composite Systems), feel free to share.

einstratege schrieb:
...But I am not aware of a 15% rule .....

This may be understandable for a layperson, but the architect or the person responsible for the verification should definitely have knowledge of it.
I have already written quite a bit about this here => SuFu

Best regards

There are some interesting TV programs about the insulation craze with ETICS (External Thermal Insulation Composite Systems).
It is said to be wrong, flammable, moisture problems between ETICS and masonry, and so on.

These programs have some entertainment value, but I wouldn’t really call them reliable sources of information. ^^

I especially find the arguments from KoFi, who seems to have to share his opinion in every show, quite amusing... Solar gains... yeah, right...

What problems are supposed to occur again with an ETICS made of EPS (expanded polystyrene)?

Flammability?
Under certain circumstances, almost everything is flammable... Does a properly installed ETICS burn spectacularly in a room fire, like shown in the 45-minute program from NDR? There is now a statement online regarding that program explaining that the test setup did not reflect real conditions, particularly due to a chimney effect... Recently, there was another fire test shown on Welt der Wunder, where a room fire was simulated by firefighters on a wall insulated with EPS... everything burned except the EPS... you can find that on rtl2’s site...
I also hardly know of any fires in single-family homes that were caused by ETICS.

Moisture?
Of course, when installing, you should make sure everything is properly sealed and that water can’t constantly run behind the ETICS... But I wouldn’t consider such major installation errors a general disadvantage of ETICS. Or would you avoid buying a car just because the gasoline engine doesn’t work if you fill it with diesel by mistake?

Special waste?
What does special waste mean? That it has to be disposed of separately and not simply put in the regular trash? Most construction debris has to be delivered separately anyway... For 100kg (220 lbs) of EPS, my local disposal site charges about €21... a whole house facade costs less than €100...

We could go on forever like this... The fact is that most of these arguments aren’t strong but mostly fear-mongering or hardly relevant! For example, EPS is not particularly vapor-permeable! Is that bad? Not really, because the amount of moisture that diffuses through walls anyway is minimal and practically negligible! Whether it’s 1% or 2% doesn’t matter... you have to ventilate to get rid of the moisture! But it sounds convincing when people say it’s not vapor-permeable... at first, it seems like it causes a damp indoor climate ^^

At the same time, a monolithic wall structure, whether Poroton (clay blocks) or aerated concrete, is not without disadvantages... I think of cracking, summer heat protection, thick walls, special anchors indoors, etc., often with a nice extra cost!

In your place, I wouldn’t get yourself worked up but critically question every single point that bothers you about ETICS!

Of course, you can build without ETICS! You just shouldn’t believe that you’re building a “better” or even “healthier” house that way... Other factors often play a much bigger role!

Shism schrieb:
...Of course, it is possible to build without external thermal insulation composite systems (ETICS)! However, one should not assume that this automatically results in a "better" or even "healthier" house. Other factors often play a much more significant role!

Agreed!

Best regards.