Cladding on plastered Leca

[Johan Gunverth]

I have a food cellar (in the basement) with plastered Leca as wall material and intend to "upgrade" the surface with some ceramic material. Probably brick veneer (20 mm thick real brick). The plastered surface is 3-5 mm thick and very porous and can be completely scraped off with some effort. I have previously treated most of it with water glass and it holds better, but it's not as hard as a thick plastered surface. What options do I have to ensure the substrate holds properly for a new coating? Tear down the whole thing or maybe treat thoroughly with water glass? The brick veneers will be set with tile adhesive and then grouted with lime mortar. I could test with a couple of pieces and see if they can be pulled off.

 

[byggarätt]

I would install a cement-based board from floor to ceiling and adhere the 20mm brick to it with tile adhesive and grout with lime mortar against the board!
Choose the thickness of the cement board so that it is strong enough to drill and hang shelves.

If you don't need to hang things, take a look at EPS boards with fiber cement like Jackon, etc., that are used in bathroom construction.

 

[sixten88]

I had scraped the walls myself until I encountered stable material. Plastered the wall with fix and then put up the brick panels. Don't really believe in a water glass treatment.

 

[Johan Gunverth]

The question is how vapor-permeable a fiber cement board is. Part of the idea with brick is precisely that the walls should breathe properly. It is cold in the basement even in summer (free cooling), so there is some moisture movement. One of the walls is against the bedrock.
When I think about it, there is probably some Flex with a really hard brush and extraction that can make the work fairly easy.

 

[byggarätt]

The question is how vapor permeable a fiber cement board is. Part of the idea with brick is precisely that the walls should breathe properly. It's cold in the basement even in summer (free cooling) so there is some moisture migration. One of the walls is against the bedrock. When I think about it, there might be some Flex with a really hard brush and suction that can make the work fairly easy

Cement boards are vapor-tight but not at the seams! Drill holes? Does condensation run today on warm summer days when it rains?

If you attach the first layer of bricks to the floor and glue the cement board standing with a gap thanks to the fact that the wall is not 100% straight.. like the cement boards, then you can leave a gap at the ceiling also against the bricks so you get a perfectly straight durable surface that breathes.