Methods of manufacturing curved staircases and staircases produced

A boxable at least partially curved staircase which employs cooperating treads and risers as a form for defining an at least partially curved path to be followed by inside and outside stringers laid up from flexible stringer strips along said curved paths to form at least a curved run of staircase of selected length, the boxable staircase comprising:

• cooperating treads and risers in a plurality sufficient to form in sequential combination at least a curved run of staircase, the treads having opposite end portions, having an end portion for the inside formed to define an inside curved path and an opposite end portion for the outside formed to define an outside curved path along the outside end portions of assembled stringers;
• said formed opposite end portions of said cooperating treads comprising notches formed along the underside of said treads to lie along the respective inside and outside curved paths;
• said plurality of cooperating treads and risers being matable in assembled sequence with a vertically oriented riser under each tread, said risers having a length such that when assembled in sequence with the cooperating treads, opposite vertical end portions of each of the plurality of risers lie respectively in a curved plane which includes the inside and outside curved paths defined by the opposite ends of the assembled cooperating treads;
• a multiplicity of flexible strips for laying up together in the form of a curved inside stringer of multiple layers, said strips being of common width and conveniently shippable length;
• a multiplicity of flexible strips for laying up together in the form of a curved outside stringer of multiple layers, said strips being of common width and a conveniently shippable length which is less than the full length of the curved stringer required to extend from one end of the curved run to the other end of the curved run;
• at least one first flexible strip for laying up along the outside curved surface of an inside curved stringer, said outside curved surface lying along said inside curved path, being in contact with one end of the risers under each tread, when assembled, and having sequential cutaway upper edge means for engaging the inside curved path formed on the inside end portion of sequentially assembled treads;
• at least one second flexible strip for laying up along the outside curved surface of an outside curved stringer, when formed, to have its outside curved surface laying along said outside curved path, being in contact with one end of the risers under each tread, when assembled, and having sequential cutaway upper edge means for engaging said outside curved path formed on the outside end portion of sequentially assembled treads;
• and
• wherein said upper edge means of said at least one first and second flexible strips are adapted to supportingly follow and engage the notches formed along the underside of sequential treads when assembled to form said staircase.