ᐅ Poroton or lime-sand brick

Tom1607 schrieb:
Well, I have aerated concrete on my exterior wall and ALL interior walls are made of 24cm (9.5 inches) calcium silicate bricks. Algae growth is a common issue with any high-insulation method, whether masonry or external thermal insulation composite systems (ETICS). The problem is that the exterior surface of the bricks is cooler because less heat passes from inside to outside, causing warm indoor air to condense on the surface, which leads to algae formation. I have this issue as well (but only on the north-facing wall since no sun warms the bricks), even though I use aerated concrete and not an ETICS.

And which type of exterior render (topcoat) do you have? Mineral-based render, silicone resin render, silicate render, or something else?

It is a lime-cement plaster that has been troweled and painted. I tried painting a section with a paint containing fungicides as an experiment (I'm generally not in favor of this because the fungicides wash out, enter the environment, and the protection lasts only about 3-5 years). This treated area remains white while the rest of the facade turns green. However, in summer it is hardly noticeable.

What color was originally used? As far as I understand, mineral-based top plaster always needs to be painted. A silicone resin paint is recommended. To my knowledge, there are also options without fungicides.

cg3980 schrieb:
Completely irrelevant? We currently live in a prefabricated house / timber frame construction (13 years old), and the heat definitely does not enter only through the windows.

There is no thermal mass present that needs to warm up or absorb heat. Prefabricated houses can be well insulated and more easily meet KfW requirements, but they also tend to cool down faster and heat up more quickly. This means there are greater temperature fluctuations—higher peaks in summer and faster drops in winter when the heating is off. For this reason alone, it was never an option for us. In addition, high-quality prefabricated houses tend to be more expensive than solid or masonry-built houses.

If budget is less of a concern, use sand-lime brick with a ventilated curtain wall facade system. Visually appealing, good sound insulation, and significantly less algae growth.

Tom1607 schrieb:
Well, my exterior wall is made of aerated concrete, and ALL interior walls are 24cm (9.5 inches) thick calcium silicate bricks.

24cm (9.5 inches) interior walls – impressive. Was that a personal preference, or was it necessary because of the Poroton blocks?