What is a Dutch basement? Many homes that bad been built over crawl spaced later had basements excavated. Instead of supporting the house and building a new foundation or underpinning, the existing footings to the new depth, retaining walls were built usually about three feet inside the basement to support the earth under the original foundation. This resulted in a somewhat smaller basement than the foot print of the house. Problems have arisen in this type of construction if the tops of the retaining walls were not adequately reinforced.