ᐅ Recommendation for Lime Plaster and Lime Paint

Hello everyone,

We have mold problems in the corners of our bedroom during winter. The base is gypsum plaster with non-woven wallpaper.

Now I plan to renovate the room a bit and want to remove the plaster from the exterior walls and then plaster them with lime plaster. After that, a complete lime finishing coat is to be applied. Finally, the walls should be painted with a lime-based paint.

I hope that the lime plaster will help regulate the humidity to some extent and prevent further mold growth.

I was recommended the following plasters:

Otterbein Clacea Base Plaster
Otterbein Clacea Fine Plaster

Does anyone have experience with these products, and do I need any primer between the plaster layers or between the finishing coat and lime paint?
Or can anyone recommend another plaster or paint?

Thanks in advance for the help.

Best regards,
Olli_35

Olli_35 schrieb:

I hope that the lime plaster will regulate the humidity to some extent

However, that doesn’t change the fact that the corner is too cold for the humidity and condensation can occur. I would rather insulate on the inside with calcium silicate boards and ventilate more.

Calcium silicate boards are a very good recommendation! Removing the gypsum plaster is the right idea. If possible, do not paint or only use a mineral-based, breathable paint. Keep furniture at least 10cm (4 inches) away from these areas. These are the measures I have seen work professionally. Personally, I would also install a single-room ventilation system in the space.

Best regards
Gabriele

Good evening and thanks in advance for your answers.

@Gabriele: So should I remove the gypsum plaster and then glue silicate boards onto it?

In general, I have often thought about using silicate boards on the interior, but I’ve also read that this can create new cold bridges. Therefore, a section shaped like a ring around the room and from the ceiling to the exterior walls needs to be installed. Another disadvantage would probably be the loss of room space, depending on the thickness.

I also wanted to install a ventilation system with heat recovery right away. However, I heard that you can hear it at night while sleeping. Because of that, I’m unsure about it.

Best regards
Olli

I researched these calcium silicate boards last night and again this morning. However, the price for this system is roughly ten times higher than that of lime plaster.

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

Could someone perhaps recommend a good decentralized ventilation system?

Calcium silicate boards are extremely durable. They are unfortunately expensive, that’s true. However, you could renovate the room relatively quickly without having to take it entirely out of use, which is not possible with fresh plaster.

Mold forms mycelium beneath the surface, and this mycelium is present in much greater quantities than what is visible on the surface. This mycelium must be removed. That is why any affected gypsum must be taken out.

Nothing grows on lime itself. But not forever; in the past, cow stables were limed every year. Lime absorbs and releases a lot of moisture. However, it releases moisture relatively slowly, so the absorbed humidity cannot be removed all at once with a quick morning ventilation.

We have a single-room ventilation system with heat recovery in the bedroom and are very satisfied with it. It is quiet but not completely silent. I can look up its exact name in our invoices this week. Ours has a flat housing on the outside; Andre77, I believe, has units that are more aesthetically pleasing and less conspicuous on the exterior. If you use a remote control powered by batteries, you don’t need to make larger openings.

It will still be as Nordanney wrote: if the temperature difference is too high, condensation will occur where the effect is most pronounced. A very cold bedroom is at risk. Airflow also doesn’t reach corners that are blocked by furniture.

Best regards
Gabriele