We bought a house that's over 60 years old. There has been one addition to the back of the house which was done with added cinder block foundation to the original mortered rock foundation. The rock foundation portion of the house is deteriorating to the extent that at certain parts the rocks are coming apart and the morter is little more than sand, and of course there are holes where water comes in. The added area of the house has "settled" so that the rear of the house (floors) is literally sloped. I am wondering if I can or should repair or replace the rock foundation, and if so how? And is it advisable to try to raise the "settled" area of the house at the same time, or in a separate operation? I am not sure if the "settling" happened before the addition, or because of the addition. People who would know that are deceased.