Plaster basement wall. Which plaster?

[MathiasS]

Exactly, that was my understanding as well.

.....but the priming mortar is made to be used under such plaster b or c........?

 

[AJ82]

.....but the primer mortar is made to be used under such render mortar b or c........?

I assumed that KC mortar would be softer than C mortar.

 

[cpalm]

I assumed that KC-mortar would be softer than C-mortar.

B and C-mortar are KC-mortar. A = Pure cement mortar, D = Pure lime mortar.

 

[AJ82]

B and C mortar are KC mortar. A = Pure cement mortar, D = Pure lime mortar.

Thanks!

 

[Gräsand]

Received feedback from Weber regarding the choice of mortar:

"Considering the year of construction, the existing plaster should consist of lime products. Therefore, I suggest you use hydraulic lime products for the repairs. Otherwise, there is a risk that you will have a stronger mortar on top of a weaker one, leading to issues such as cracking.

If there are surfaces with plastic paint, it is good to scrape off all the paint and apply a thin plaster.

Leave the surfaces unpainted to allow them to breathe as well as possible. A limewashed surface looks nice as it is. A tip is to work the surface first with a damp float, and then finish with a damp lime brush, drawn horizontally. Rustic and nice in its simplicity. If you still wish to paint, you can check out our lime-based paints.

Suggestions for suitable products:
Webercal 109
Webercal 159
Webercal 158
Webercal 148"

 

[MathiasS]

"Given the year of construction, the existing plaster should consist of lime products. For this reason, I suggest using hydraulic lime products for the repairs. Otherwise, there's a risk of having a stronger mortar on top of weaker, leading to issues like cracking.

To avoid this problem, I chipped off the old plaster and then used a steel brush in a drill to brush the entire wall. Now, I have bare concrete (hollow brick) to plaster on, and I can use whatever I want... and what I apply will stick.

 

[Fulkemisten]

Had just like Weber recommends used lime paint on that, or real silicate paint which is a powder that you mix with what is called water glass. All pre-mixed silicate paint probably contains some kind of organic polymer?

Alternatively actually drain. Right from the start, you know.

 

[AJ82]

Speaking of war concrete, how is it best to repair holes in that type of wall? Since the wall partly consists of large stones, they leave a lot of air behind if they fall out. I imagine it might not be good to use too strong a repair mortar considering how soft the wall is?

 

[BosseHansson]

Thought it looked like plastic paint, is that correct? Knocking down the plaster feels like an option. A sating machine with a steel brush might work. I sanded off lots of such paint plus gypsum filler many years ago. It wasn't great, today I would have hired a blasting company and done all the spaces at once in the basement.

 

[Dublin]

I would have done exactly as Weber recommends and used lime paint on that, or real silicate paint which is a powder mixed with what's called water glass. All pre-mixed silicate paint contains some kind of organic polymer, right?

Alternatively, actually draining. Getting it right from the start, you know.

I agree. When it comes to silicate paint, Hornbach has their own which is not pre-mixed and is used with their silicate binder. I have used that system with good results.

 

[z_bumbi]

May I guess that the boiler was removed more than 5 years ago and not replaced with radiators, ventilation, and/or a dehumidifier?

As long as you have a heat source that extracts air, the house manages humidity from outside, but when the boiler disappears, the humidity builds up. Drainage is nice, but a good dehumidifier and a radiator are cheaper, especially since the floor is not drained.