How to Smooth a Concrete Wall Finish | Home Guides | SF Gate
Aug 08, 2019· Foundation.All concrete block walls must rest on a sturdy foundation of poured concrete. The depth and size of the foundation will vary depending on the size of the concrete block wall and the weight it must support, but a typical freestanding wall requires a foundation that is about twice as wide as the wall itself and which extends about 1 foot down below the frost line.