How to Build Porch Stringers

Place a 2-by-4-inch wood board on the edge of your porch where you want to install the stairway. Ensure the end of the board extends beyond the edge of the porch. Tape a 4-foot carpenter's level to the board to ensure it is plumb. Use a measuring tape to determine the distance between the board and the ground below to calculate the total rise, or vertical space, the stairs have to cover.

Decide on the run or horizontal distance of each step, which is usually 10 inches. Also, divide the total stairway rise by the desired rise for each stair, which is typically 7 to 8 inches. Round the result to the nearest whole number before you record it. For instance, if the total rise is 71 inches, divide it by 7 to arrive it to arrive at 10.14, or 10 steps. To arrive at the rise per step, divide the total rise by the number of steps, which is 7.1 inches.

Set the 2-by-4-inch wood board on the edge of the porch so it slopes down at a 40-degree angle. Use the corner of the board that rests on the ground as a rough guide to determine how far out the stairs will extend. Hold another board down from the edge of the porch, and measure the distance to the landing. Divide the measurement by the number of stairs to arrive at each stair’s depth.

Lay a 2-inch-by-12-inch wood board on a cutting table and mark the notches on it for each stair’s rise and run. For instance, if you want each stair’s rise at 7 inches, position the thin side of the framing square so the edge of the stock lines up with the measurement. Draw a straight line along the edge of the square to trace the measurement on the stock.

Match the flat side of the square against the desired depth, for instance 10 inches. Draw a line against the flat side of the framing square to mark the stair’s depth. Repeat this process to form notches for the stairs on the stock.

Measure 1 1/2 inches upward from the rise of the lowermost stair and mark the point on the stock with pencil. Also, measure 3/4 inch downward from the rise of the topmost stair and mark the spot with a pencil. Cut the stock at the points using a handsaw. Dry-fit the board between the lower surface of the porch and the ground, ensuring it forms a tight fit. If required, trim excess length using a saw.

Place the board back on the cutting table and carefully cut along each notched mark using a saw to form the first stringer for your porch.