I am going to start a kitchen remodel on a mid 40's home that is constructed with concrete block on all exterior and filled concrete block center wall up to the second floor. Floor joists span approx 13' (on each side of the center solid wall, and supported by the concrete blocks with notches out of the blocks.
I know I do not need the sister joists to span the entire length, BUT if I wanted them to span the entire length should I make the notch larger in the concrete block in order to fit the sister joist? OR do I only span the length needed to help with deflection of the floor.
Existing joists are 2x10 but are actually much older than the house as they were re-purposed in the 40s from a farm house.
What are your thoughts?