Wooden stairs have been used for many, many years in all types of residential construction. The standard closed stairs consist of two parallel spaced apart members, called housing or stringers, which support a sufficient number of treads and risers to span the distance between the two levels for which the stairs are designed. The stairs are usually laid out on the job site. The conventional method of preparing the components for assembly of the stairs is to use a router on the job site to machine grooves at the appropriate locations in each of the stringers. These grooves are generally tapered and they receive the treads and risers at right angles to each other to form the stairs. The tapered grooves provide for the use of wedges so that the treads and risers can be properly positioned relative to each other. Once properly positioned, each of the treads and risers is secured in place by nailing, by the use of a suitable adhesive or by using other fasteners. The most common method is to nail the treads and risers in place, and if the appearance of the stairs is important, moldings can be used to cover the nail heads. Moreover, even if the components of the stairs are premachined in a manufacturing plant, it is virtually impossible to cut and fit the risers and treads so as to eliminate all gaps between them. Moldings can then be used to cover these gaps.
Stairs constructed using the foregoing described conventional technique can be custom produced and assembled in a manfacturing plant and then shipped to the job site for installation. Such stairs are obviously bulky and expensive to ship, and must be installed in the proper sequence of construction or it may become difficult to install the stairs. Moreover, the contractor must make certain that the distance to be spanned by the stairs between the two levels and the opening for the stairs are accurately measured and constructed. If not, the pre-manufactured stairs may be very difficult to install. To avoid these problems, it is sometimes customary for the stairs to be cut, assembled and installed on the job site. This, of course, requires more time since mass production factory techniques cannot be employed. In either event, however, it generally requires sixteen or more man hours to layout, cut the components and assemble the stairs. This time can be considerably more where more expensive decorative woods are used instead of pine or fir. Stairs, therefore, can be a relatively expensive portion of a construction project.
Many of the disadvantages of constructing stairs using the foregoing described conventional techniques can be eliminated by the use of the interlocking techniques disclosed and claimed in my prior U.S. Pat. No. 4,154,032 issued May 15, 1979 and entitled "Stairs and Method of Making Same." However, even with these techniques the stringers must be individually machined to produce the proper rise and run so that the completed stairs will fit properly.
When using the techniques of the invention described herein, the layout, cutting and assembly time of any stairs, either conventional or interlocking, can be substantially reduced thus reducing the cost. With the interlocking stairs, the time for installation in the field is one man hour or less. Moreover, the cost of producing and stocking the components can be reduced because the components are standardized regardless of the opening where the stairs is to be installed.