Cut Underlayment Opening

What happens here

After removing the shingles, inspect the exposed roof underlayment. Remove any remaining roofing nails using a hammer or the claw end of the pry bar. Use a utility knife to make a precise cut through the roof underlayment, creating an opening that matches the dimensions required for the post anchor's base. It's recommended to use a measuring tape and a straight edge to ensure the cutout is accurate and straight. The video shows the existing underlayment being black felt paper and then a self-adhering material beneath it.

Goal: Create a precise opening in the underlayment