ᐅ Interior and Exterior Plastering (Aerated Concrete) – Important Considerations

Hello!

I have many questions and hope to get expert answers.

For the house construction, I have decided to do the interior and exterior plastering myself.
My construction company planned to apply cement-based plaster in the bathroom and kitchen, and gypsum plaster in the other rooms.

I did some research online as a layperson and chose pure lime plaster. The shell will be made of aerated concrete (30cm (12 inches) thick), and according to the builder, no additional thermal insulation is necessary.

My cousin is a bricklayer (though he hasn’t worked in the trade for a while), and I want to plaster with him—he can do that. However, he prefers to use lime-cement plaster (interior plaster) and mix it himself. From what I’ve heard, most people recommend using ready-made lime mixtures because mixing your own can lead to many mistakes, and the sand must be of very good quality (washed, etc.).

Now, my questions about the interior plaster. It should be noted that I only want to paint the walls, no wallpapering anywhere, except for tiles in the bathroom, of course:

1. Lime-cement plaster or lime plaster (gypsum plaster is basically not an option for me, or is it?).
2. Pretreatment for the aerated concrete before plastering (wetting, anything else? Primer or something similar?).
3. Base coat plaster—one layer? How to finish/smooth it afterwards (lime smoothing plaster or something else? plaster/filler).

Exterior plaster:

4. What should be used as the base coat?
5. Pretreatment?
6. According to the building specifications: mineral scratch render, grain size 2mm (about 0.08 inches). What exactly do they mean by this type of plaster?
7. Base area, with cement mortar. I think that’s fine.
8. I have heard that today it is no problem to apply the finishing render (what exactly is it made of?) “immediately” after the base coat, without waiting for a year for the house to settle. The house will be built without a basement, if that matters.

Hmm? No more questions come to mind right now, but I’m sure I’ll have more later.

I’m looking forward to your answers and would like to say thank you in advance!

Hello,

Mahoon77 schrieb:
The shell is being built from aerated concrete (30cm (12 inches) thick), according to the construction company, additional insulation is not necessary.

Apart from your other questions, which will surely be answered here with practical experience: what is 30cm (12 inches) aerated concrete supposed to be sufficient for? KfW 85/KfW 70 or better, and what systems are planned to be installed?

Kind regards

Hello building expert!

First of all, thank you for your response. We are not using KfW; we have the standard program that is required. Solar panels will be installed on the roof, as this was a condition. The building permit/planning permission was granted without any conditions. I found the following in the building permit/planning documents:

Load-bearing and bracing walls, exterior and interior:

30/17.5 cm (12/7 inches) aerated concrete masonry

Exterior plaster/external wall cladding including insulation and substructure:

Mineral-based render

What else do you need to know?

Thank you

Hello!

I checked again, and the building permit / planning permission was issued according to the applicable Energy Saving Ordinance 2009, so everything is fine. That works out. I just want to know which plaster is best for aerated concrete.

Thank you

Doesn’t anyone have any advice or suggestions???

Mahoon77 schrieb:

Does no one have any pros and cons or advice here???

Bringing this back up. Any recommendations today? I would like to use lime-cement on ytong.

For gypsum, just wetting and priming is enough. Is there anything else to consider here?