Photos: Hillary Clinton's life in the spotlight. Clinton waves to the media in January 1996 as she arrives for an appearance before a grand jury in Washington. The first lady was subpoenaed to testify as a witness in the investigation of the Whitewater land deal in Arkansas.
1 Adding a basement to an existing house can cost $30,000-$70,000 or more, depending on the size of the existing crawlspace or half-basement or if the house is on a slab foundation, and how much of the work is do-it-yourself and how much is done by contractors.
On average, slab foundations cost about $20,000 to $30,000 for mid-to large-sized homes. However, keep in mind that prices vary based on the size and layout of your home, and your geographic location.he cost of a raised foundation varies widely based on the size of your home, its layout and the region of the country where you live. For an average-size home, you can expect to spend around $30,000 to $40,000 in most regions of the country.