Non-laminated, self-configuring, variable pitch spiral stairset and method of fabricating spiral stairway

A spiral stairway, formed from a stairset, for extending from a lower floor level to an upper floor level, said spiral stairway comprising:

• a central support column extending vertically from a lower floor level to at least an upper floor level, said central support column formed from a center support and a plurality of spacer elements surrounding said center support;
• a plurality of generally triangular stair tread units extending radially outward from said central support, each said stair tread unit having a proximal end and a distal end, said proximal end rotatable around said center support and separated from an adjacent stair tread unit by one of said spacer elements, said stair tread units rotatable with respect to each other around said central support and being of a number to equally divide a distance between the lower floor level and upper floor level with a uniform vertical spacing therebetween;
• a spiral banister spiralling around said central support column, said banister having a plurality of substantially rectangular segment members and a tensionable cable threaded through each segment member, said segment members being a selected whole number for each stair tread unit, at least one end of each of said banister segment members being beveled whereby tensioning of said tensionable cable forms said plurality of segment members into a curved member for forming said spiral banister, said banister further having a substantially rectangular further segment member at each end, said further segment members containing a tensioning means for tensioning said cable;
• a first vertical newel post attached to the lower floor level;
• a second vertical newel post attached to the upper floor level, with first and second opposite ends of said banister attached to said first and second newel posts, respectively;
• and
• a plurality of vertical balusters, each said baluster joined at an upper end to, and extending downwardly from, an outwardly-directed side surface of a segment member of said banister and joined at a lower end to a corresponding stair tread unit, whereby upon loosening of said cable, said stair tread units remain rotatable with respect to each other around said central support column.

A method for assembling a stairway on-site that extends from a lower floor level to an upper floor level from a stairset having a plurality of stair tread units and a banister, said stair tread units each having a downwardly-extending bracket extending along a leading edge, and said banister having a plurality of substantially rectangular segments threaded by a tensionable cable, said segments being of a selected whole number for each stair tread unit, each said segment having at least one beveled end to contact an adjacent segment, said method comprising:

• forming a central support column extending from a lower floor level to at least an upper floor level, said central support column comprising a central member threaded through alternating spacer elements, said spacer elements having a height corresponding to said stair tread unit bracket, and through proximal ends of said stair tread units;
• arranging said stair tread units in a spiral array around said central support column;
• fastening a lower end of an upright primary baluster to said brackets of each said stair tread units;
• rotating a top stair tread unit to be adjacent the upper floor level, and attaching said top stair tread unit in position;
• fastening a top end of said upright primary baluster of said top stair tread unit to an outwardly-directed surface of a corresponding segment of said banister;
• rotating a next to said top stair tread unit to a position partially beneath said top stair tread unit until said upright primary baluster of said next to said top stair tread unit is positioned proximate to a corresponding segment of said banister;
• fastening a top end of said upright primary baluster of said next to said top stair tread unit to an outwardly-directed side surface of its corresponding segment of said banister;
• fastening a leading edge of said top stair tread unit to a trailing edge of said next to the top stair tread unit;
• continuing positioning and fastening stair tread units and primary balusters between stair tread units and outwardly-directed side surfaces of said segments of said banister to complete all stair tread units of said stairway;
• attaching top ends of balusters intermediate said primary balusters to outwardly-directed side surfaces of segments of said banister, and lower ends to said stair tread units so as to be parallel with said primary balusters;
• tensioning said cable threaded through said banister segments to make said banister rigid and of spiral configuration;
• and
• fastening a lower end of said banister to a lower newel post at the lower floor level and an upper end of said banister to an upper newel post at the upper floor level, whereby upon loosening of said cable, said stair tread units remain rotatable with respect to each other around said central support column.

A banister for use on a spiral stairway that extends from a lower floor level to an upper floor level, said stairway having a plurality of stair tread units extending radially from a central support column said banister comprising:

• a plurality of substantially equally-sized first banister segments having rectangular parallel side surfaces, parallel top and bottom surfaces, and rectangular end surfaces to abut adjacent first banister segments, at least one end surface oriented at an angle to said side surfaces to achieve a curve when said plurality of first segments abut, each said first banister segments provided with a passageway extending between end surfaces and positioned midway between said top and bottom surfaces and midway between said side surfaces, there being a selected whole number of said first banister segments greater than one corresponding to each of the stair tread units;
• a cable member extending through said passageway of each said first banister segments, whereby said first banister segments are rotatable with respect to each other about said cable member;
• a further banister segment on at least one end of said cable member containing means for tensioning said cable after installation through said first banister segments;
• a plurality of substantially vertically oriented baluster members each having one end attached to one of said first banister segments on an outwardly-directed surface proximate a midpoint between said end surfaces, said baluster members having a second end for attachment to one of the stair tread units to establish a height of said banister above the stair tread units;
• and
• attachment means at ends of said banister for attachment at the upper and lower floor levels.