OP here. We had the structural engineer come years ago, had underpinning done, but cracks were behind paneling so didn't do anything with them at that point. It's a dry basement so no water issues. But I'll check into hydrolic cement.

We had major foundation issues after a kitchen reno and addition. Structural engineer used bracing and hydraulic cement. Not sure how severe your issues are but it's only a few hundred bucks to get an inspection.

We have a single family rambler, but I'll second the plug for hydraulic cement. (ha, no pun intended) We patched all over our cinderblock foundation and then painted with DryLock and regular paint over that. The basement is actually quite cozy now.

And I don't know if you have to be horrified - I've read horizontal cracks are actually worse than vertical.

We filled in our cracks about 10 years ago with hydraulic cement and its been fine. If they are deep, put great stuff behind it and then fill the cracks. I would fill them because if water from the outside can follow different paths and come in. We had water leaking through the cracks and no issue since.

Mix it, put it on.. simple

http://www.homedepot.com/p/DRYLOK-4-lb-Fast-Plug-Hydraulic-Cement-00917/100553093

umm this is a very stupid idea and open you up to liability down the road. Get a structural engineer to look before you do anything.

We are renovating the basement of our DC rowhouse. Our house has had some serious settling (several vertical cracks that go from basement to attic.) The house has since had underpinning but the cracks still expand and contract a little during the year (it's easy to track in the attic). (I know, some of you are horrified but the house is in NW and probably worth $800k despite these issues.)

Most of the foundation cracks are in a party wall that is inside the basement of the neighbor's house (so no water or cold air coming in). Still, I'd like to fill the cracks with something before we drywall. I have read that the best thing is epoxy--you buy a kit with several ports and pump the stuff in. Apparently this is what is done with foundation cracks in tunnels, bridges etc to stop movement.

Is it worth the hassle, though? I'm not sure it will really do anything to stop the ongoing slight movement of a 3 story brick house. Seems like the cracks will just open again, or some smaller crack will open. Also if we're going to fill them, it would ideally be done in the spring when the cracks are smallest (fall is when they are largest).

Instead I could just fill them with foam spray (Great Stuff)--it will insulate and should move with the cracks. Then maybe cover with cement but since it's behind drywall, not sure that's necessary.

Anyone have advice about what to do? (Besides run screaming from this house, which we decided not to do long ago?)