How to Cut Stair Treads With Square Guides

Stick a piece of masking tape onto the outer edge of the tongue arm of a carpenter square at the 8-inch mark. This will determine the height of each stair riser. Place a second piece of tape onto the outer edge of the base arm of the framing square at the 11 inch mark. This will denote the tread length.

Place the framing square onto a length of 2-by-12 inch lumber, which will serve as a staircase stringer. Begin at the upper end of the stringer and place the square elbow in so that the riser marker leads and the tread marker follows. The tape should sit flush against the edge of the lumber. Use a pencil to trace around the outside edge of the framing square to form an outline of the risers and treads.

Move the framing square further down the 2-by-12 so that the outside edge of the tongue arm rests against the end of the tracing you just made. The idea is for each set of marks to start off right where the last set ended. Repeat the tracing process for the next step. Continue to outline risers and treads along the length of the stringer. A series of peaks and valleys, reminiscent of a saw blade, should result.

Cut along the pencil lines with a circular saw as far as you can go. Use a jigsaw to cut any remaining edges or hanging portions to avoid damaging the stringer. The stringer is now ready for risers and treads. Place this cut stringer over another length of 2-by-12 and trace along the edges with the pencil to ensure a perfect replica. Cut it in the same manner as the first stringer.