PATENT APPLICATION

OF ROBERT EVERETT SORENSON ₅ JR.

TITLE: STAIR SYSTEM WITH EXPANDABLE CENTER

CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority from the United States patent application filed on 28 June 2006; application no. 11/168,208.

STATEMENT REGARDING COPYRIGHTED MATERIAL

Portions of the disclosure of this patent document contain material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office file or records, but otherwise reserves all copyright rights whatsoever.

FIELD OF INVENTION

[0001] This invention generally relates to a staircase system, more specifically to an adjustable staircase system and, still more precisely to a staircase system with expandable center that is easily and quickly built, cost effective and is safe to be installed by an average worker.

BACKGROUND OF THE INVENTION

[0002] A major cost portion of any construction project, whether residential, commercial, or industrial, is that of stair construction. The specialized nature of stair construction, coupled with the multitude of individual pieces that may fit exactly, various building codes that may be met and the various materials that can be used, make it necessary to use highly skilled craftsmen to design and construct stairs. These craftsmen are necessary whether building one stair or multiple stairs of the same design, because of the small variations between floor heights, and floors may lead to a not so perfectly level or square. Accordingly, the need has arisen, for the development of the Stair System which provides the flexibility of expansion in height and length and at a low material and labour cost.

[0003] US Patent number 5,890,330 discusses an adjustable staircase system; where adjustable steps extend between two parallel stringboards. Each stringboard includes two locking flanges and each step is supported by four pivotable blocks each securable to a flange by means of a nut. Two threaded rods extending through the step and between the stringboards engage two respective nuts combined with two opposite blocks. The height of each step of the staircase may be adjusted by changing the spacing between the blocks along each flange. The horizontal position of the steps may be adjusted by changing the vertical distance between the front blocks and rear blocks along the stringboards, regardless of the angle at which the stringboards were fitted. A universal staircase may thus be achieved. Considering various aspects this system is limited in many ways as pivotable blocks make the assembly bulky and costly without added benefit adding towards extra installation time.

[0004] In another US Patent number 5,636,483 a system is discussed where a prefabricated stair system having individually pivotally mounted right angular brackets on opposed stringers, has a control bar which removable contacts the brackets to assume all brackets are arranged at the same angles with respect to the stringer so that the treads, which are supported by opposed

pairs of brackets, are parallel to the floors and the risers supported by the brackets are perpendicular to the treads. The stair system is shipped as a kit and assembled in situ following a method of assembly and installation. This system as the system is made to order and thus limited in its scope in various ways and having many components making the assembly complicated and time consuming for installation.

[0005] The above mentioned prior arts and some other related works are either expensive or cumbersome for assembly and require highly skilled craftsman to design and construct stairs and thus they are time consuming in construction and increasing the labour cost as well. So there is a need for a low cost and a simple adjustable staircase system which can be installed quickly by an average worker providing more strength to all the stair treads.

OBJECT OF THE INVENTION

[0006] In view of the foregoing disadvantages inherent in the above- mentioned techniques, a general object of the present invention is to obviate above and other drawbacks associated with the prior art.

[0007] The object of the invention is to provide with a staircase system.

[0008] It is further object of the present invention to provide with an adjustable staircase system.

[0009] Another object of the present invention is to reduce the assembling complexity of the system.

[0010] It is yet another object of the present invention to make the system cost effective.

[0011] Still another object of this invention is to reduce the required installation time.

[0012] It is still another object of the invention to provide with an attachment of a temporary handrail.

SUMMARY OF THE INVENTION

[0013] One aspect of the present invention is a staircase assembly comprising a plurality of stringers, and; a plurality of stair units, having treads and risers wherein stair unit is secured by means of fastening means on each corner to said plurality of stringers.

Said stringers, having a diagonally shaped series of equally spaced substantially vertical structure notched out of one side to define the length and height of each step of the stair assembly.

The said tread, forming a channel by rolling the leading edge for holding the riser of the stair unit installed immediately below, and each stair unit is secured by means of fastening means on each corner to said plurality of stringers, said channels further engaging other stair unit laterally sliding for providing horizontal adjustability.

[0014] A staircase assembly further comprising tread having catching holes at a predetermined distance that is identified according to the length of the staircase, and a handrail assembly having a handrail posts, securing means, and rails, handrail post designed for fixing to the holder of said stringers through the catching holes of said treads and securing means are configured for clamping this assembly tightly to said stringers.

[0015] According to the another aspect of the invention an adjustable staircase assembly having a plurality of stairs each stair having a base unit having a receiving grove at its angled corner, and a stair unit having a first projecting structure, a curved structure and a second projecting structure, for fixing on top of said base unit, characterized in that the said first projecting

structure is configured for fixing it into the said receiving grove of the base unit, and the curved structure is configured for clamping the said second projecting structure of a second stair to form a staircase assembly.

[0016] The invention described herein is not limited to above description, any other embodiment implementing the concept of instant invention will fall under the scope of the present invention and will be the subject matter of the protection.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a perspective view of the stair system with expandable center;

[0018] Figure 2 is an inside or left-hand view of the stair system with expandable center with an exploded view of the bottom stair unit showing greater detail, according to a preferred embodiment of the present invention; [0019] Figure 3 is an opposing perspective view of the stair system with expandable center, with an exploded view of the bottom stair unit showing greater detail;

[0020] Figure 4 is a piecemeal view of the stair system with expandable center, prior to final installation;

[0021] Figure 5 is a perspective view of a stair unit; and

[0022] Figure 6 is a side view of a stair and base unit attached together, according to an alternate embodiment of the present invention.

Reference numerals

20... outer stringer

25... central stringer

31... riser

32... tread

33... corner bend

34... lip

35... bolt hole

36... handrail aperture

37... lap seam

41... handrail post

42... post receptacle

43... bracket

44... handrail system

46... first projecting structure

48... receiving grove

50... second projecting structure

DETAILED DESCRIPTION OF THE DRAWINGS

[0023] A further understanding of the present invention may be obtained with reference to the following description taken in conjunction with the accompanying drawings. However, the embodiments used for describing the invention are illustrative only and no way limiting scope of the invention. A person skilled in the art will appreciate that many more embodiments of the invention are possible without deviating from the basic concept of the invention any such embodiment will fall under the scope of the invention and is a subject matter of protection.

[0024] Figure 1 is a perspective view of the stair system with expandable center shown as a complete built system of its components. [0025] Figure 2 shows the left-hand side view of the stair system where

DETAIL A shows the configuration of the individual stair units and their relationship to each other.

[0026] Figure 3 is a front perspective view of the stair system and illustrates the sliding engagement between two individual stair units and the corner bent 33 so created. DETAIL B provides greater detail of the attachment point of the handrail system 44, specifically the handrail post 41 secured within

the post receptacle 42. The handrail system 44 comprises handrail posts 41 , brackets 43, and rails and is generally tubular on shape and lightweight, yet resilient in construction. The post receptacle 40 is designed to receive the handrail post 41 and is cylindrical is shape with one open end and means to lock the handrail post 41 in place. The inner diameter of the receptacle 42 is slightly larger than that of the handrail post 41 and is constructed of similar materials. A bracket 43 is affixed to the inner wall surface of the right-hand stringer 20 to retain the post receptacle 42 to said stringer 20.

[0027] Figure 4 shows the stringer boards 20, 25 that are typically a diagonal-shaped device with a series of 90° angles notched out of one side to define the length and height of the tread 32 and riser 31 portions of the stair system. The stringer boards 20, 25 should all be of equal shape and size and utilize conventional mechanical fasteners when installed to the building framework.

[0028] Figure 5 shows the stair units should all be of equal shape and size. The stair unit is bent at a 90° angle making a corner bend 33 which defines the tread 32 and riser 31 to match that of the tread and riser cut-outs on the stringers 20, 25. The leading edge of the tread 32 is formed into a lip 34, or "C"- channel which doubles back against itself to a point upon which the clearance between the lip 34 and the riser 31 portion of the stair unit installed immediately below. The lip 34, of individual stair units 34 are designed to sliding engage each other laterally, thereby defining a left- and right-hand stair unit. Both left-hand and right-hand stair units have bolts holes 35 drilled there through on the left side and right side, respectively for affixing the stair unit to its respective stringer 20. The right-hand stair units also have an aperture 36 drilled there through at the bottom, top, and every seventh or central stair unit to accommodate the handrail system 44.

[0029] Figure 6 illustrates an alternate embodiment of the stair system.

The stair assemblies here include two separate units, riser 31 and a tread 32, a retaining clip to connect two stair units together, and a sliding assist piece.

DETAILS A and DETAILS B show the bends and configuration for the riser and stringer, as well as the shapes of the second projecting structure 50 and lip 34. The material of construction for the base and stair unit may be the same as is shown in FIG. 5 and the retaining clip and sliding assist piece for vibration dampening and minimal friction may be an ultra-high molecular weight (UHMW) polyethylene or other material with the same properties. DETAILS A and B show the bends and configuration for the stair and base units, as well as the shapes of the retaining clip and sliding assist piece.

[0030] The preferred embodiment of the present invention is designed to be used by a normal person with some skills and minimal training necessary. [0031 ] The stair system with expandable center 10 is designed for the fabricator or building contractor in mind. Custom building flights of stairs can take a lot of time that could be used to complete other tasks. Therefore, a reliable and easily constructed modular stair system that can fit any situation such as is presently defined can become a great time and resource saver. [0032] The present invention is designed to be pre-fabricated off-site according to the general specifications of the construction and transported to the site for final fitting and finishing in the space provided. The first step is measuring the total height and width by laying out the rise and run of the stringers 20, 25 that will be cut. The height is determined by the measured distance between the finished bottom floor to the top of the upper deck and the width is generally determined by standard building codes. Two (2) outside stringers 20 and a third central stringer 25 are identically cut to form the support structure of the stair units 30.

[0033] The next step required is to form the tread 32 and riser 31 from the sheet stock of the stair unit 30 to the required shape. A 90° angle is needed to define the boundary 33 of the tread 32 to the riser 31. On the opposite end of the tread 32 from the bend 33, a lip 34 is formed by rolling the leading edge about a radius and doubling back against itself creating a "C"-shaped channel, through which another stair unit 30 similarly formed can slide therethrough. The backwards bend of the lip 34 should result in minimal clearance between the lip

34 and the front-facing surface of the top of the riser section 31 of the bottom stair unit 30. Apertures or slots 35 are then formed at spaced intervals near the same edge of the tread 32 and riser 31 to accommodate nails or bolts. Care must be taken here to form identical stair units 30. Half of the stair units 30 should have the formed bolt holes 35 on its right side (see FIG. 5) and the other stair units' bolt holes 35 formed on the left side. Also, the handrail pole aperture 36 is cut out on a desired side of the tread 32 of every seventh stair unit 30 as per OSHA guidelines (see FIG. 5), and ensuring that the bottom, top, and at least one central stair unit 30 are included.

[0034] At this point, the finished stair units 30 should be secured to the top and front surface of the stringers 20, 25. Handrail pole receptacles 42 are mounted on brackets 43 are to be installed on the inside surface of the stringer 20 at locations corresponding to the bottom step, top step, and seventh or central step at a position below the projected placement of the stair unit 30 (see FIG. 3, Detail B). Edge and pressure blocking may at this time be attached at the top and bottom of each stringer 20 for use during final installation. The pre-fabrication of the stair system with expandable center 10 is now ready for transport to the job- site, along with the central stringer 25 and handrail system 44. [0035] When the pre-fabricated stair system 10 has been delivered to the job site and placed in the space provided, final installation of the device 10 should commence (see FIG. 4). The right and left sides of the system 10 are adjoined together by overlapping the "C"-channels 34 of the treads 32 of one side overtop the other side, providing a sliding engagement between the two (2) sides. It is important at this stage to ensure that the side with the temporary handrail pole apertures 36 are on the outside edge as opposed to abutment of the stair system 10 against a wall. One side of the stair system 10 should be secured to the building framework with the other side manipulated into place by sliding the entire side until it abuts the framework on the opposite side, at which point it is secured thereto. The central stringer 25 is then secured at a central point underneath the stair system 10 by bolts, screws, or nails driven through the tread 32 and riser 31 portions of the overlapping stair units 30, preferably in the

same pattern as used to secure the separate stair units 30 to their respective stringer 20. Any height adjustment is inherently minimal due to building code regulations on riser 31 height and are accounted for by the overlap and bend of the lip 34 formed at the leading edge of the tread 32 portion ("C"-channel) during pre-fabrication.

[0036] The handrail system 44 is then installed where needed by feeding the poles 41 through the apertures 36 located on the tread 32 and secured within the receptacle 42 mounted to the inside of the stringer 20 via a bracket 43 by a channel lock or similar system. A similar securing system is present for installing the handrails to the pole 41. Both the handrails and poles 41 may be expandable as necessary. This handrail system 44 is necessary due to OSHA requirements and may be easily removed and the apertures 56 covered with a cap or plug when the handrail system 44 is not installed.

[0037] Additional finishing for the handrail system 10 is generally left up to the building fabricator or stair constructor but typically involves the use of an adhesive or coating to protect the stair system 10 and to cover, protect, and level the lap seam 37 formed during final installation. It is conceived that an adhesive tape will be applied to the lap seam 37 to effect a smooth transition for carpet applications. Edge and pressure blocking for final construction may be attached during pre-fabrication or during final installation.

[0038] It is conceivable that other alternate embodiments for the present invention may provide additional support and ease of construction. A "T"-channel piece designed for attachment directly to the top surface of each stringer step, with the extended piece fitting within a similarly shaped and sized notch formed downward from the top surface of said stringer step, provides added support for the stair units.

[0039] A more elaborate design involving a separate tread and riser stair unit and base unit with more bends are referred to in FIG. 6. The sliding point in particular has a separate rounded extension piece offset from the corner bend defining the riser and tread boundary and running the entire width of said boundary. This rounded piece is received within a similarly yet opposite shaped

groove on tne oase unit. I ne base unit is placed first on top of the top and front facing stringer surfaces and the tread and riser stair unit is placed on top of the base unit, with the vertically interlocking pieces corresponding to specialized bends at the leading edge of the tread portion. Vibration dampening devices such as UHMW polyethylene fill in the space and secure said stair units and base units together at the lip joint and at the sliding point to provide a smoother movement between the lateral stair units.

[0040] The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.