I recently bought a house that was built in the early 1920's. It is in San Diego CA and has a foundation that is okay. The house has sunk down slightly but was inspected and seems to be due to some water from poor drainage. I know what to do to fix that but I am interested in attaching the foundation to the house so that if there is a "Big One" the house will remain on the footings. Is there any problem with just increasing the number of support beams and adding footer under the new supports on the foundation? I have been reading up on foundations but I am not sure how deep to sink new footers and is there any thing wrong with increasing the number of supporting beams under the house. It only has a crawl space. Thank you.