To adjust for the thickness of the tread when laying out a stringer, what should be done?

When laying out a stringer for a set of stairs, adjusting for the thickness of the tread is essential to ensure proper alignment and fit. The correct action is to shorten the bottom riser by an amount equal to the tread thickness. This adjustment is necessary because the bottom riser height is measured from the finished floor level to the top of the first tread. By shortening it, you account for the thickness of the tread that will be installed, ensuring the top of the first tread aligns correctly with the top of the riser.

This approach maintains the overall rise consistency across the flight of stairs while accommodating the actual materials being used. It prevents the riser from being too tall or creating a step that is uneven after installation, leading to a safer and more aesthetically pleasing staircase.

Adjusting the top riser or leaving the risers unchanged would not account for the additional height introduced by the tread, potentially resulting in steps that are not uniform in height, which can be hazardous. Extending the top riser would also complicate the rise calculations without solving the issue at hand. Thus, shortening the bottom riser is the most effective and accurate solution for this layout problem.