Expansion Joint Material

[happyhacker]

I have a 1970s end Terrace and it is built on a concrete raft (stretches under all 6 properties). The internals are either concrete or Breeze block and the outside walls purbeck stone block. At the party wall junction to next door there seems to be an expansion joint filled with some sort of fabric material (stringy). Someone has faced this with mortar. I feel I should give this a better cover as the weather could get in where the mortar is falling out. What is the accepted expansion stuff to use to provide a cover for the existing stuff? I was thinking of pressing it in to provide a bit more depth for any new stuff.

Would there also be an expansion joint on the inner wall?

 

[^woody^]

Polysulphide mastic

There would not normally be an internal movement joint as the internal leaf is divided up by the party walls - whereas the external wall is continuous

 

[happyhacker]

Thanks, yes I can see that would be the case. What I don't understand is that this "expansion joint" is adjacent to a corner where the outer wall turns around to the next properties external wall due to the properties being offset at their party walls by about 1m. Unless this filling serves some other purpose why should it be adjacent to a corner?

 

[^woody^]

Corner returns are good places for movement joints as otherwise, the wall moves and pushes the corner out or creates a vertical crack from DPC to soffit level