Stains on the plaster and visible joints

Hello everyone,

Our house was built in 2020 with Poroton (42.5 cm bricks, no ETICS) and plastered. I cannot provide more detailed information about the plaster.

On the west side, we see stains on the wet exterior wall and the joints are also slightly visible. On the dry wall, the stains are barely visible. Other exterior walls, whether on our house or the neighbors', show no abnormalities.

I understand that plaster develops mold over time. However, I wonder why the stains are only visible so clearly when wet. Is the plaster too thin, so that the masonry "shows through"?

I have an appointment with the builder soon, so I look forward to your neutral opinion. Thank you!

I would name 2 reasons for this: the applied plaster is too thin.

And the paint used has no algicide and fungicide. In addition, no water-repellent paint was used, so water can penetrate the top layer. Due to the different drying behavior, it looks like this after a short time.

In 2-3 years, it will look even worse.

Presumably, you also did not agree on a second coat with the construction company?

I would have the facade cleaned and painted with proper paint.

Who has to cover the costs and what is stated in your contract determines who has to pay.

Thank you very much for the feedback!

The stains usually appear on the north wall, where in the wetter climate the surface no longer dries. And then you see (or do stains appear?) stains. This can be seen on many houses – even those with different wall constructions, but only with white plaster.

In our case, the phenomenon was visible from about the 7th year. In spring, the plaster is noticeably brighter, from autumn it is spotted.

However, we also ordered a better plaster with fungicides. The standard was the simpler mineral plaster.

So if you haven’t ordered and paid for an upgrade, you will probably have to accept it as it is. My opinion.

Such a thing cannot be known by a layperson at all. Especially how it was written whether one agreed on 1 or 2 coats. You can search the internet as much as you want, but I would never have come up with something like that in my life. That you are basically delivered an unfinished facade and it is nothing else. I would immediately ask myself whether applying it too thinly is a defect, or if you are more or less forced to book a thicker layer so that it turns out right. Although that would already be very borderline.

Then you have to get professional help ;)

At BER, people also like to complain that no experts were brought in, but politicians wanted to act as site managers themselves... in house construction it unfortunately seems to be normal that people completely lacking technical/craft knowledge think they can manage it themselves.

That's what comes out of it. Unfortunately.