Single Beam Staircase . The single stringer beam is made from hss (hollow structural steel) and can be powder0coated to almost any colour, including brushed brass. 0 likes | 33 downloads | 103 views download. interior single tread metal stairs Búsqueda de Google Staircase from www.pinterest.com.mx This type of stringer uses a single beam, usually steel or stainless steel, that sits underneath the stair treads and provides the support for the stairs. Table 5.8 4 calculate min. These are installed in the field using traditional methods such as hoisting, or by using a traveling crane with.