I would like to know if it is possible to add a second floor on an 8" CMU foundation wall? My home (built in 1966) is on a flat site, with non-expansive soils, in a temperate, dry climate. The foundation has no cracks that I can see and since the basement is currently 80% finished I know that it is also water-tight - no leaks that I have seen. It appears that the house is level with no settling. In short the house seems very solid. The first floor walls are 2x4 stud walls. I have found a logical place for the stairs. I've checked local codes and it appears that I am well within height and setback limits.

I thought before I consulted with a structural engineer I would ask if 8" CMU walls can typically support a new second story addition or not. If they can typically support a new second story addition is the retrofit required (if any) any more or less costly or complicated than an 8" concrete wall. I appreciate any feedback anybody has!

If it was built according to code,it should be no problem if you have the soil that can handle the load. The dead load from the sevond floor is frequently an assest if you have block walls.

The thickness of a foundation is usually dictated by the lateral from the soil and not the vertical load. If it was not for the soil, you would probably have a 6" wall.

There are many 2 and 3 story homes built on 8" block foundations. The record for a 8" loadbearning (no steel or concrete columns) block building is about 30 stories and the tallest 6" block building I have seen is 22 stories.

You should have an engineer to look at the existing structures and verfy that there are no unusual loading conditions that could cause locaized problems.