This should give you a better idea how to
connect a stair stringer to a concrete building foundation. As you can
see in the picture above, we're using treated 2 x 4 lumber to set the
stair stringers on.
The treated lumber is then fastened to the concrete using a high-powered
tool that shoots anchoring pins into the concrete. If you look in the
picture above, on the center treated 2 x 4, you will notice one of these
pins, towards the bottom of the picture.
You can use different types of framing anchors to attach your stair
stringers to the concrete.
Split Level Stair Framing