Recommendation for lime plaster and lime paint

Hello everyone,

we have mold problems in the corners of our bedroom in winter. The substrate is gypsum plaster with fleece wallpaper.

Now I will renovate the room somewhat and want to chisel off the plaster on the exterior walls and then plaster with lime plaster.
Then a complete lime topcoat plaster should be applied.
Finally, it should be painted with a lime paint.

I hope that the lime plaster will regulate the humidity reasonably well and that no more mold formation will occur.

I have been recommended the following plasters:

Otterbein Clacea Grundputz
Otterbein Calcea Feinputz

Does anyone have experience with this and do I need any primer between the plaster layers or between the topcoat plaster and the lime paint?
Or can someone recommend another plaster and paint?

Thanks in advance for the help.

Best regards
Olli

I hope that the lime plaster regulates the humidity more or less

But that doesn't change the fact that it is too cold in the corner for the humidity and it can condense. I would rather insulate on the inside with calcium silicate boards and ventilate more.

Calcium silicate boards are a very good piece of advice! Removing the gypsum plaster is the right idea. If possible, do not paint or only use open-pored mineral paint. Keep furniture 10 cm away from the areas. These are the measures that I see becoming successful professionally. Privately, I would additionally provide the room with a single-room ventilation system.

Best regards
Gabriele

Good evening and thanks already for the answers.

: So should I remove the gypsum plaster and then stick silicate boards on it?

In general, I have often thought about silicate boards from the inside, but I have also read that this creates new cold bridges. So you would have to install a piece in a circular shape from the room and from the ceiling to the exterior walls.
The further disadvantage would probably be the loss of room size, depending on the thickness.

I also wanted to do the ventilation with heat recovery right away. But it was said that you can hear it at night while sleeping. Therefore, I am also unsure about that.

Best regards
Olli

I looked into these calcium silicate boards yesterday evening and also this morning. But the price for this system is about ten times that of lime plaster.

I think lime plaster in combination with a decentralized ventilation system with heat recovery is a good solution.

Can someone perhaps recommend a good decentralized ventilation system?

Calcium silicate boards absorb an incredible amount. Unfortunately, they are expensive, that’s true. But you could renovate the room relatively quickly without taking it completely out of operation, which certainly isn't possible with fresh plaster.

Mold forms mycelia in the substrate; these are quantitatively more than what is visible on the surface, and these mycelia must be removed. Therefore, infected gypsum must be taken out.

Nothing thrives on lime itself. But not forever, in the past cow barns were limed every year. Lime absorbs a lot and releases a lot. But it releases relatively slowly; you cannot get rid of the absorbed moisture all at once by airing out in the morning.

We have such a single-room ventilation with heat recovery in the bedroom and are very satisfied with it. It is quiet but not inaudible. I can rummage through the invoices this week to find out exactly what it’s called. Ours has a flat casing on the outside; I believe Andre77 has some that are more aesthetically pleasing and unobtrusive outside. If you can get by with a remote control with a battery, you don’t have to add so much.

Nevertheless, it remains as Nordanney wrote: if the temperature difference is too great, condensation occurs where the effect is most pronounced. A really cold bedroom is at risk. Airflow also doesn’t reach corners cluttered with furniture.

Best regards Gabriele