O
otello471117 Sep 2017 19:24Hello
I am currently renovating my 30-year-old bathroom.
I plan to fully tile only the wet area inside the shower and tile halfway up the wall at the washbasins.
The rest will be finished with lime plaster.
After removing the tiles, I discovered gypsum plaster underneath.
To level out the unevenness caused by removing the tiles, I want to apply filler to the wall and then cover it with a lime plaster with a grain size of 0.1–0.5mm (0.004–0.02 inches).
The lime plaster will be applied only as a thin top coat, about 1–2mm (0.04–0.08 inches) thick.
Could you give me some advice regarding the materials, filler, and lime plaster?
I have read that some lime plasters (e.g., "Bau Mit Glätte") are not suitable for application on gypsum-based substrates. Why is that?
I would appreciate any tips you could provide.
Best regards, Otello
I am currently renovating my 30-year-old bathroom.
I plan to fully tile only the wet area inside the shower and tile halfway up the wall at the washbasins.
The rest will be finished with lime plaster.
After removing the tiles, I discovered gypsum plaster underneath.
To level out the unevenness caused by removing the tiles, I want to apply filler to the wall and then cover it with a lime plaster with a grain size of 0.1–0.5mm (0.004–0.02 inches).
The lime plaster will be applied only as a thin top coat, about 1–2mm (0.04–0.08 inches) thick.
Could you give me some advice regarding the materials, filler, and lime plaster?
I have read that some lime plasters (e.g., "Bau Mit Glätte") are not suitable for application on gypsum-based substrates. Why is that?
I would appreciate any tips you could provide.
Best regards, Otello
F
fach1werk21 Sep 2017 08:16Lime plaster is mineral-based, meaning it chemically bonds with a (also mineral) substrate through silicification. This process creates crystalline connections within about 4 weeks that are inseparably linked.
Gypsum is not mineral-based. Therefore, the crystals in lime plaster cannot bond with it. There are primers available, but it must be said clearly: you are essentially sticking one layer onto another. It’s not a perfect bond, but it is unlikely to fall off the wall. Lime has quite sticky properties.
Using lime plaster in a bathroom is generally a very good idea. It absorbs moisture and releases it slowly. However, releasing moisture slowly also means it retains dampness to some extent. If you take a long, humid bath on a Sunday and your bathroom becomes thoroughly moist, then ventilate afterwards, the humidity level will easily return to that of other rooms. Because the lime releases moisture slowly, the level will rise again by about 10% after ventilation.
Shower areas: You probably know that grout lines are never completely waterproof, so primers are necessary under shower floors. Even additives used for swimming pool grout are not bad, though they can be harsh.
Enjoy your design process
Gabriele
Gypsum is not mineral-based. Therefore, the crystals in lime plaster cannot bond with it. There are primers available, but it must be said clearly: you are essentially sticking one layer onto another. It’s not a perfect bond, but it is unlikely to fall off the wall. Lime has quite sticky properties.
Using lime plaster in a bathroom is generally a very good idea. It absorbs moisture and releases it slowly. However, releasing moisture slowly also means it retains dampness to some extent. If you take a long, humid bath on a Sunday and your bathroom becomes thoroughly moist, then ventilate afterwards, the humidity level will easily return to that of other rooms. Because the lime releases moisture slowly, the level will rise again by about 10% after ventilation.
Shower areas: You probably know that grout lines are never completely waterproof, so primers are necessary under shower floors. Even additives used for swimming pool grout are not bad, though they can be harsh.
Enjoy your design process
Gabriele
In our bathroom, two walls were made with hollow bricks, and the other two walls were primed with concrete (one more than the other due to different absorbency) and then directly sprayed with lime plaster.
In the upstairs bathroom, the lime plaster was applied only up to the height where tiling was not planned anymore.
In the upstairs bathroom, the lime plaster was applied only up to the height where tiling was not planned anymore.
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