After plastering - Moisture

Hello forum,

Over the past two days, we have had our hallway plastered with mineral plaster (Knauf), both in the basement, the ground floor, and the upper floor, including the staircase inside.

Yesterday, shortly before the work was completed, I noticed that a lot of condensation had formed on the glass of the front door. According to the plasterer, this is normal because the work and the plaster are "breathable". We should ventilate properly over the next two days, which can only be done through various rooms (office upstairs, bedroom, bathroom, guest toilet), since we do not have a window in the hallway itself.

This morning I noticed that besides the plastic front door, which was very damp, there were also drops on the recessed LED spotlights, probably because of the metal around them. Additionally, there were drops on the hatch to the attic, but only on the thick screw heads (metal, cold). The wall or ceiling itself was nowhere damp.

Now I have two questions:

1. Is there a risk of mold? During the night, I did not ventilate because I don’t like to leave the windows open to the street or garden. This morning I opened everything again wide.

2. If the LED spotlights are damp, could there be electrical problems? In the ground floor hallway, the lamps are currently only hanging on sockets, a third lamp in a small cloakroom is not connected at all; the cables are hanging, which I secured with insulating tape. The sockets and switches have also not yet been installed because the plaster was not completely dry yesterday.

Or am I worrying too much again?

Hello Campino,

since the plaster was also mixed with water, it is now quite normal that it is more humid inside the house (is your heating already running?) than before.

With two to three thorough bursts of ventilation a day, it should be possible to get it under control without mold forming immediately.

For us, it was extremely humid after laying the screed and even after the wallpaper was applied to the wall (water in the paste), there was a clear increase in humidity. On all smooth and cold surfaces (windows, metal plates, etc.) we also had water droplets (condensation).

Regards,

Dirk

But we managed that well with regular ventilation.

All right, thanks to you.

We already have the heating on in the rooms, but there is no radiator in the hallway. Maybe we should also turn on the heating in the rooms we open and where we open the windows, and perhaps fire up the stove (wood stove) in the living room?

Well, airing out and running the heating at full blast at the same time doesn't help all that much.

Theoretically, drying with heating and airing should work like this:

1. Open all windows (cross ventilation) for about 10 - 20 minutes to achieve a complete air exchange.

2. Close all windows again and turn on the heating. This warms the cold air and allows it to absorb the moisture present in the room (the warmer it is, the more moisture it can absorb).

3. => continue at 1.

You shouldn’t air out for longer than 10 - 20 minutes either, otherwise the surfaces will cool down too much.

However, I am not a specialist in plaster – so I don’t know if the wood stove is a good idea. I could imagine (layman’s opinion) that too much heat is not good for the plaster either…

Best regards,

Dirk