There is no definitive answer to this question as it depends on a variety of factors, such as the climate and soil conditions in your area. However, some of the most common types of foundations for houses include concrete slabs, crawl spaces, and basement foundations. Concrete slabs are one of the cheapest types of foundation to install and are perfect for areas that experience mild climates. Crawl spaces are a less expensive option than basements and can be used in areas with warmer climates. However, they do require more maintenance than other types of foundations. Basement foundations are more expensive to install but offer greater stability and protection against weather conditions.

The cheapest foundation for a house is a concrete slab. It's also the most durable and long-lasting foundation, but it can be difficult to repair or modify once it's been installed.