In this video

The fully assembled stair stringer frames are carefully brought over and positioned under the front porch. The workers then mount these frames to the existing porch structure, driving deck screws through the top bracing into the porch joists. They continuously check for plumb, level, and square using an Empire spirit level and a measuring tape to ensure the stairs are perfectly aligned and at the correct height. The bottom of the stringers are secured into the ground (likely concrete or compacted earth) using a Hilti gun, which fires powerful shots to anchor the wood, preventing any movement when people step on the stairs.