New Foundation: Minimum height of concrete above openings
I am pouring a new concrete foundation for my existing house. The foundation walls will be 8' high and 8" thick of 3000psi reinforced concrete. The house has a large 8"x8" beam running along the entire perimeter of the house that will sit on top of the new foundation walls.
I would like to have several openings for 2' x 2' windows in the foundation walls. I would like to place the windows below the top of the wall leaving a span of concrete between the top of the windows and the top of the wall. My question is, what is the minimum height that this span of concrete should be? Obviously there will run rebar across the span, but I am still worried about cracking if I don't go thick enough. I am currently working with 6" of concrete above the windows in my plans.
I would appreciate any thoughts.