Precast stairs are a very popular method of construction. When used within a steel frame, they may be supported directly onto steel beams etc. Frequently they are installed within a concrete stairwell enclosure and different methods of support are needed.
The stairs may sit onto an angle bolted to the stairwell wall. The choice of fixings is wide, post-fixed drilled fixings, cast-in sockets, and cast-in channel. Of these, cast-in channel offers the greatest tolerance on site, and may even avoid the need for shimming or packs. This channel is often supplied in the form of a ‘ladder’ for ease of installation.
With this detail, it is usually necessary to take measures to protect the angle against fire, corrosion and to improve visual aspects.
As an alternative to angles, there are proprietary products that are cast into the stair element and extend into recesses in the stairwell walls. These have the advantage of not being visible from the underside, and hence not requiring protection. They also allow stairs to be installed rapidly.
These inserts (TSS) are positioned at mid depth and do not appear on either the top or bottom surface. Similar inserts (RVK) project to the upper surface and are usually covered by screeds etc.
Both types can be insulated to improve transmission of stepsound in public staircases.