Drop the Stringer by One Tread Thickness or Your Bottom Step Will Be Tall

The Problem

You lay out a stringer with perfectly equal rises, cut it clean, and the finished stairs still feel wrong — the bottom step is taller than the rest by exactly one tread thickness. The math was right; the adjustment was missing. Once treads go on, every step's walking surface moves up by the tread thickness. Step two rises from the top of tread one, so the added thickness cancels out — everywhere except the first step, which rises from the floor.

The Technique

The fix is one cut, made before the stringer goes in:

1. Lay out and cut the stringer with all rises equal, as normal.
2. Before installing, cut an amount equal to the tread thickness off the bottom of the stringer — the surface that sits on the floor.
3. The whole stringer drops by one tread thickness. Now the first tread's walking surface sits at exactly one rise above the floor, and every step above it matches.

Carpenters call it "dropping the stringer," and skipping it is the most common reason a finished staircase fails the equal-rise check that codes and feet both notice.