What is your opinion on filling block foundations with concrete?
Our house is a little over 100 years old, with a cinderblock foundation walls in the basement. We’ve got a minor crack in the grout, and we were advised to fill the block with concrete for strength, in addition to repairing the grout.
Thanks in advance
That's a structural question that we would be unable to answer unfortately, since a crack in a block foundation may indicate an issue but may also be of no consequence at all. It's really impossible to know without looking at it, and the stakes are too high to advise you in a course of action without looking at it.
I don't know who it was that advised you but before undertaking any work I would want the opinion of someone who isn't motivated by securing an expensive repair contract, like a building inspector or engineer, someone who can give you a well-informed but unbiased opinion about how you are best to proceed.
I can say that in general that a block foundation is weaker than a poured foundation, so any cracks should be more closely examined, and block foudations are better insulated on the outside than on the inside in order to keep them warm and not subjected to the seasonal freeze/thaw cycle. Good luck, I'm sorry we can't help more.