on repairs to STAIRS

With the effects of time & gravity, all buildings tend to settle as they age, but they don’t settle uniformly. In what’s known as differential building settlement, the interior wood framing shrinks and settles more than the sturdier outer walls. Since most stairs are attached to an interior wall on one side, differential building settlement may cause the staircase to sag away from the wall, toward the newel post or stair well. Repairing a staircase with a significant settlement problem is best done from below.

Before that work can begin, however, it’s essential to figure out the center line of the stair, says Steve Payne, co-founder of Payne-Bouchier Fine Builders in Boston. “If you don’t do that, the stair is never going to work out right.”

Finding the center line is simple if you follow this rule: the line always follows the handrail. The edge of the staircase and the positioning of the risers around any turns are controlled by this center line, from the handrail down through the balusters or spindles. It’s the fixed point around which all the other elements of the stair move.

This is especially true in certain rowhouse neighborhoods in Boston, where the typical mid-19th century stairs are elliptical-well, continuous-rail staircases that run