small projects

posttensioned stair

concrete and steel.

The post tensioned stair began
with somewhat more humble
origins - its concrete cantilevered
treads of an earlier design had
been so badly constructed, they
had to be entirely redone. In an
momentary bout of contrariness,
the client saddled the rebuild
with an added task of having the
treads held away from their side
wall, effectively eliminating the
continuous joint required for a
properly cantilevered support.

The stair found redesign as
floating wafers hung from wall
anchors on one side and steel
rods on the other. With the post-
tensioned rods serving functions
of both structural support and
baluster, the resolving detail was
found in freely rotating threaded
locking cylinders at the base of
each rod to serve as a finishing
detail and for lateral stability,
and the levelling of each tread.