Why is this slate in my wall?

[terrlor]

Hi everyone,

Removing damp plaster and came across a big chunk of slate, it appears to be the same in a couple of different locations. Anybody know why this might be here?

It's a cottage built approx. 1900

Images show where it is in the wall (just below what was a built in shelf), a closer up look at the wall and the chunk that came off.

Thank you for any insights!

 

[aockenden]

Is it sandwiched between layers of cement?

 

[terrlor]

Is it sandwiched between layers of cement?

Yes! At least that's what I think it is

 

[aockenden]

Yes! At least that's what I think it is

There were a few places on my walls that had similar flattish pieces of stone sandwiched between layers of cement. I suspect it was low-spots that the builders were trying to bulk-out to be flat with surrounding sections before applying their second coat. Likely they were pushed into the first coat while it was still wet.

 

[terrlor]

Interesting! Mystery solved and I can crack on with removing, thank you