I live in a terraced house built around 1900 I think. The walls are solid no cavity.
In the loft the party wall mortar is crumbling away. You just have to touch the mortar and it crumbles to the floor. I think the bricks are quite soft as they are very easy to drill into.
should I repoint with lime or cement based mortar. At some point I may render as it gets very dusty up there.
any help would be appreciated