tiling onto old lime plaster? - Tile Advice

[user123]

All I have ever been told about lime is that you can't paint on top of it, not with anything else but lime anyhow, it would throw it off.

Now I have just been asked by a mosaic friend if it is possible to mosaic onto old lime plaster walls (external) - over to you - any ideas?

 

[Ajax123]

it would need to be well and truly sound. Most old lime plasters and renders I have come across are loose and not particularly strong. I am not sure you would be able to use a cement based adhesive either. I know that you are not supposed to repoint a wall built with Lime mortar using cement based mortar cos the cement is much too hard and does not allow the mortar joints to "breathe"
I wonder if you could make your own Lime based adhesive using burnt and slaked lime......that could make a really interesting project

 

[White Room]

All depends how stable the lime is, I would imagine this is a very old property and to start a general tap on the render to find out if it's hollow or still solid and depending how flat it is.

It could also be a lime with a sand/cement render.

 

[user123]

it would need to be well and truly sound. Most old lime plasters and renders I have come across are loose and not particularly strong. I am not sure you would be able to use a cement based adhesive either. I know that you are not supposed to repoint a wall built with Lime mortar using cement based mortar cos the cement is much too hard and does not allow the mortar joints to "breathe"
I wonder if you could make your own Lime based adhesive using burnt and slaked lime......that could make a really interesting project

All depends how stable the lime is, I would imagine this is a very old property and to start a general tap on the render to find out if it's hollow or still solid and depending how flat it is.

It could also be a lime with a sand/cement render.

It would be interesting wouldn't it, but it won't be my project, unless it turns into it, because the mosaic artist who asked me might not be able to do it. I did get the impression by the short message that indeed it is an ancient property. I will have a conversation with her about it tomorrow afternoon, she is in America, don't know how she is connected to this UK project.

 

[doug boardley]

I'd say not G, unlike normal sand/cement render, lime mortar readily absorbs moisture then expunges/wicks it out slowly, not sure I'd like that process happening behind something I'd tiled tbh.