ᐅ Hollow bricks and mineral insulation—are they a poor combination?

Hello Alex85!

Alex85 schrieb:
And I’ll gladly burst your bubble that this is an inexpensive alternative. The extra cost is about €35 per sqm (sq ft) compared to ETICS with EPS. Besides the higher material price, the installation effort is greater because EPS is simply glued onto a smooth base (which should be the case for new builds ), while mineral wool is fastened with dowels. The dowels cost money and especially time. Depending on the house, this can easily add up to an additional €10,000 compared to EPS. It’s no small sum.

Stop, I’m not saying mineral insulation is a cheap alternative—but cheaper than monolithic construction for KfW 55 or even KfW 40 standards, if I understood correctly, so priced between plastic-based ETICS and monolithic construction. An extra €10,000 is acceptable, especially for better indoor climate if what’s written can be trusted. And I simply don’t want us to be sealed in entirely with plastic *brr*.

Alex85 schrieb:
Besides mineral wool, which doesn’t like to get soaked (you need to install it quickly and apply the exterior render right away, then that’s sorted) because it loses its insulating effect. But “mineral insulation” doesn’t necessarily mean mineral wool. There are also mineral insulation boards like Ytong Multipor or Webertherm MD. These are not cheap either and their drawback is the poorer thermal conductivity class 045 (mineral wool and EPS 035, Neopor 032), meaning the boards are somewhat thicker to achieve the same insulation.

Ytong Multipor sounds great! Does it also “work well” with hollow brickwork or bricklayers who use hollow bricks, or is there a better alternative more suited to hollow bricks? Webertherm MD seems to be for internal insulation? The mineral-based ETICS I found all seem to have an EPS base—do you need that? If so, that makes it kind of pointless; if optional, I’d skip it, which might make this a potential option. Some photos even suggest it’s specifically marketed for bricks.

Alex85 schrieb:
Please do not take horror stories about any wall construction too seriously. Every building material has its pros and cons, and no one intentionally uses total failures. Building companies always proclaim as great whatever they like to use themselves.

But plastic-based ETICS is rubbish.

Best regards & many thanks,
Christian

crion schrieb:
Stop, I’m not saying that mineral insulation is a cheap alternative – but it is cheaper than monolithic construction for KfW 55 or even KfW 40 standards, if I understood correctly so far, so priced between plastic-based ETICS and monolithic construction.

That depends, and I wouldn’t agree with that as a general statement. However, with ETICS you achieve better insulation performance with a thinner wall assembly, which also means saved space.

crion schrieb:
An extra cost of 10,000€ is acceptable, especially for better indoor climate if what’s written can be trusted.

You can’t really trust that; it’s voodoo. Anyone promoting their building materials always talks about indoor climate. It’s nonsense. Walls don’t actually “breathe,” by the way, if that’s the next topic.

crion schrieb:
And I just don’t want to seal us completely in plastic *brr*

That’s fine. You need to be comfortable with your decision (no, not in terms of indoor climate comfort ). However, “sealing in plastic” is mostly psychological and not rationally justified (which doesn’t mean that EPS-based ETICS don’t have downsides – they do).

crion schrieb:
Does it “work” with high-perforation bricks or masons working with them, or is there a better alternative that fits high-perforation bricks?

I would rather say that high-perforation bricks are not the best base for ETICS. Sand-lime brick is your friend. They are flat, provide sound insulation, allow for secure fixing, and so on.

But in general, I’m not sure if this combination makes much sense. It seems “red” brick with ETICS is quite rare, but that could also be regional.

crion schrieb:
WeberTherm MD seems to be interior insulation? The Weber ETICS mineral-based ones I found all had an EPS base – is that necessary?

Yes, that’s right, I was mistaken. But there are certainly ETICS made from other materials as well: hemp, wood, PUR, phenolic boards, even vacuum insulation panels. In the base area, XPS is mostly used due to its compressive strength, yes. The same applies under slabs and under underfloor heating (where EPS is often used). Those examples show that even a monolithically built house will come into contact with EPS. But I don’t see that as a big problem.

crion schrieb:
But plastic-based ETICS are rubbish

Depends on whom you ask and how you define rubbish. The fact is, this discussion is full of passion. You can dig that up through the search function as well.

Alex85 schrieb:
But basically, I’m not sure if that combination makes much sense. It feels like you rarely see "red" with ETICS, but that might also depend on the region.

Here, including for the original poster, a lot of construction is done with Poroton. Houses built with Poroton plus ETICS make up the largest group of new builds in this area. However, I also believe that sand-lime brick is the better alternative if you choose to go with ETICS.

Hello to both of you!

Just very briefly: The FIBAV company group we currently favor (Königslutter near Braunschweig) offers perforated bricks with external thermal insulation composite systems (ETICS) according to their building specifications (fire protection class B2, which sounds very much like polystyrene or similar) – there is no mention of calcium silicate bricks.
In your opinion, what insulation would be more suitable for these bricks? Our insulation should be non-combustible and not emit potentially toxic gases in case of fire...
It also should not contain potentially toxic fire retardants that could leach out over the years.

This does not seem reasonable to me, especially concerning the terms “toxic” and “combustible”/“fire”...

Best regards,
Christian

B2 sounds like EPS indeed.
HBCD has not been included in EPS since 201x. However, I would be interested in what exactly is supposed to leach out.

Facade fires in single-family homes are very rare, and B2 does not mean it burns like tinder. By the time it burns that fast, you would already be out of the house.
But that is my opinion and a good example of how these topics are often exaggerated. Of course, manufacturers of mineral wool emphasize the better fire resistance of their products, which is true, but I strongly doubt whether the widespread panic about EPS is justified. Grim stories of burning houses certainly help boost sales [emoji4]

Home insurance policies covering fire are not more expensive for EPS facades than for monolithic facades. This is an indication of how risk management professionals assess the situation.

I believe that as a client, one should not get too caught up in the siding debate for its own sake. No concrete house planning benefits from daydreaming about organic bricks or imagining your house covered in moss and marked by woodpeckers. Both extremes give the ordinary building component—the exterior wall—a mythical significance, when in fact it is simply meant to separate the inside from the outside and support the roof. The craft of building should be left to those who have mastered it long before these trendy discussions even existed. Even aspects that are not insignificant can still be greatly overrated. Every building material falls short of being a perfect solution in different ways. What is certain, however, is that you can create quality problems by forcing your masons experienced with X to work with Y.

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