Mark the Lumber for Cutting

What happens here

Begin by selecting a piece of treated lumber (e.g., 'Prowood' brand, ground contact rated) that will serve as the deck post. Use a speed square (e.g., 'Milwaukee' brand) and a pencil or carpenter's marker to accurately mark the dimensions for a notch or dado cut on the lumber. The marking should define the area to be removed so the post can fit snugly into the existing deck frame.

Goal: Accurately mark the post for a notch to fit the deck frame.