I have a 1920 2-family house just north of Boston.
The foundation is old cinder blocks, and the mortar is crumbling in many areas.
It certainly looks like someone tried to patch a few areas prior to me buying the house ~ 10yrs ago, and by my guess, used the wrong mortar (i.e. probably too strong)
The basement is unfnished, does get damp (I run a dehumidifier), and does get pretty dusty from the crumbled mortar.
there is also a chimney cleanout that's in very bad shape (fireplace unused)
My goal here is not to finish the basement, but simply ensure the integrity of the foundation, and possibly apply some coating to the wall in the hops of brightening the place (I do use it as a hobby workshop/woodshop) and keeping the dust & humidity under control.
I also have no illusions that coating the walls on the inside "waterproofs" anything.
I read that "N" mortar is not for below-grade, but "S" mortar is likely way too hard and will just acause more problems...
any suggestions ? local recommended pro/resource ?