ᐅ Best mineral-based insulation material that prevents algae growth on masonry?

Hello Forum

I am quite new here, and all the details about my project can be found in the introduction thread.

Currently, insulation is the most interesting topic for me, and I have a few questions that I haven’t been able to answer so far.

I have decided against using polystyrene (and similar) systems and want to use mineral insulation instead. Whether to use glass wool or rock wool has not yet been decided...

Are there any arguments that distinguish between the two?

With external insulation, the problem often arises that the outer wall stays cold and a lot of moisture condenses on it. This then leads to algae growth and can possibly penetrate into the masonry. The latter can be avoided by installing a membrane...
These two problems were specifically mentioned for polystyrene systems, but I believe they also apply to mineral insulation, right?

What should be considered to prevent algae growth with mineral insulation?

tulamidan schrieb:
...With external insulation, the common issue is that the outer wall remains cold and a lot of moisture condenses on it.

Is the counterargument that the outside of the wall should be warm? ;-)

tulamidan schrieb:
...What should be considered to prevent algae growth on mineral insulation?

Ask your designer. It’s also helpful to look at neighboring countries, for example Switzerland. There is a lot of experience and research on this topic there!

Best regards

That would logically be the counterargument, but there is no need to discuss the rationale.

Undamped houses can usually absorb and release a certain amount of moisture. This "breathing" is prevented by the membrane, causing moisture to condense, which creates ideal conditions for algae growth.

It is currently being reported in the media that with external wall insulation systems (EWIS), algae growth is mainly prevented through chemical means. I would like to avoid that... the only question is: how?

I do not have a planner yet...

tulamidan schrieb:
...Uninsulated houses can usually absorb a certain amount of moisture and also release it again.

When an external wall absorbs moisture, regardless of the source, the improved thermal conductivity caused by this significantly increases heat loss.

tulamidan schrieb:
...This "breathing" ...

The myth of "breathing" walls apparently still persists ;-) There are far more examples of exterior insulation and finish systems (EIFS) where no algae growth occurs than the other way around. Presenting isolated cases as a general trauma for the whole system is somewhat simplistic.

tulamidan schrieb:
...It is currently reported in the media that algae growth on EIFS is mainly prevented by chemicals.

Yes, the media is a reliable and solid source of advice. 😕

tulamidan schrieb:
...I would like to avoid that... the question is: How? I don’t have a planner yet...

Then you need to consult a specialist for this.

Best regards.