Bricks, Masonry, Asphalt and Concrete - Crumbling Brick Foundation

I have a house from 1895 with a brick foundation to it. The house originally had some severe water problems (no gutters, many trees) which have since been taken care of. Several of the bricks are to the point of crumbling when touched, and there are some major seepage problems.

What can be done to stop/improve the deterioration? Can bricks below ground be replaced? Can the mortar be replaced? Would applying a skin of concrete over it all be a possible solution, or only hide the problem & make it worse?

Assuming the entire basement brickwork needed repaired & the basement floor is 2,200 sq feet, can you give me a very rough idea of cost (worst case scenario)?

Thank you very much!
--John

Deteriorated brickwork is replaced. Above and below grade repairs (brick and mortar) are possible. A wide range of damp proofing solutions exist but a concrete skin is unlikely choice. A perimeter drain "french drain" will probably be on the include list.

With foundation brickwork crumbling under touch seek engineering advice and talk to qualified restoration masonry contractors. A rough range is 10% to 30% of the new construction cost. Over 30% and it time consider other options.

Thanks… will excavation be needed, or should they be able to replace brick & mortar from the inside only?

Minimally excavation is required for damp proofing and a perimeter drain. Determining the condition of the exterior brickwork before making a full commitment is logical also. During replacement excavation relieves side wall pressure and helps keep dirt from falling into the work or basement.