Have a 2 story  70 year old house with settlement problems (flat lot) and a disintegrating 3 foot basement wall and a cracked slab abutting it. Winter rains cause water intrusion in the basement area so french drains are an obvious intervention but not clear if perimeter drains pumping water to the street would halt the puddling water which could also be wicking up from underneath slab as the area may have hidden underground water in the neighborhood. Overall $’s spent will be a consideration and contractors looking at the job have focused only on one 40 foot perimeter foundation wall that shows spalling and outright concrete chunks detachment. The other walls don’t show cracking out nor do they present with that one  inch crack- out along the exterior stucco telegraphing through from stud wall underneath along the sill line.

Questions: what are the implications of only dealing with the one obviously failing wall and leaving the other three walls alone other than placing french drains at their base? This one obviously failed wall would receive new 24 inch footings, sill, and shear wall applied on interior (so no removal of exterior stucco so as to avoid restuccoing job-easier to sheetrock over inside 1/2 inch plywood installed), along with bolting and hold downs and rebar attachment at corner intersections, thus seismically improving that one wall while also getting a new foundation (but bids have only covered about half that wall for seismic improvement because access gets difficult in places, the minimum required by code in California with attention being focused out from the corner intersections with adjacent walls). Studs would be cut off 6 inches then reconstructed near the sill by toe nailing new extension 2x4s. First is there any risk in dealing partially with a seismic retrofit on only one wall of the house leaving the other 3 walls of the basement level untouched? I’ve heard that the one strengthened wall could act as a fulcrom in a seismic shaker, thus torquing the rest of the un-worked on house.  True or is one wall work better than nothing? Should I insist that the whole wall be retrofitted or if only the readily accessible parts be done. There is also a  30 foot high, 4 foot wide brick chimney in the middle of that wall run that is settling and showing cracks like the rest of the wall on that west side of the house. There are proposals to also form a concrete base under that fireplace footprint to keep it from settling more , although there is evidence of  a 2 inch wide vertical crack on both sides of the chimney where it meets the framing of the house as if it wants to fall into the street even without an earthquake. No one yet seems particularly interested in bracing the chimney back against the house, thinking it could stress the framing in a decent size earthquake if it was structurally attached (could be dissassembled and repalced with wood construction but money scarcity is an issue). So the plan presented there is simply to stucco patch the crack  with the expectation that the crack will stabilize if the subsoil  brick footprint is beefed up with concrete while the rest of the wall is getting a new concrete foundation. Feedback on partial seismic work vs total seismic shear and bolt, one wall foundation replacement work, chimney salvaging work and any opinions on what this might cost if a minimal job was undertaken or alternatively, a more major reconstruct effort undertaken?