Modular staircase system

Abstract

A modular staircase system configured to form a curved staircase, support extremely heavy finishing materials, having higher design tolerances, and can be achieved at a relatively moderate cost. A plurality of stair modules are configured to secure to one another to form a complete staircase system, each which has an elaborate stringer of significant strength and moderate weight configurable to create floating staircases at an affordable cost.

Description

FIELD OF THE INVENTION

The present invention generally relates to staircase systems utilized in the building industry.

BACKGROUND OF THE INVENTION

A conventional staircase system includes a plurality of ascending/descending steps laterally extending between a pair of stringers, each of the steps include a tread portion and a riser portion. Stairs are expensive due to the high cost of the materials, as well as the skilled labor required to make and construct such systems. The labor can easily exceed the cost of the materials in even the most basic staircase systems. As the complexity of the staircase increases, including designing curves, landings, and floating stair systems, the price exponentially escalates due to the cost of the materials, the wasted materials, and the additional labor.

Staircase systems area complex works of art. Stair owners have unlimited choices of material to cover their stair with. It could be as simple as oak treads, oak riser, oak skirt boards, oak balusters, and oak handrails, to as complex as Italian Marble treads, Italian marble risers, Italian marble skirt board, Italian marble balustrade and Italian marble handrails. When considering the different types of materials, the load factor for the two stairs described above are at two ends of the scale. Stair builders utilize wood stringers and risers or steel stringers and risers to carry the loads associated with the chosen materials. With the complexity of building and designing stair systems, many of the stairs are fabricated off site and then transported to the job site and then installed.

In high-end staircase systems, curved stringers are often made from large expensive cold rolled steel. Steel stringers which may extend in the vertical direction in excess of 12 feet lineally extend 20 feet or more. These metal stringers are extremely difficult to tool given both the tooling tolerances, as well as the variations of the material over temperature. The longer the stringer, the more likely that tolerances can lead to a staircase that fails to meet the design requirements in its intended location. Given the extreme pricing of the tooling and the steel stock, it is an expensive task to simply scrap the stringer. More elaborate designs include multiple landings, which increase the stair complexity and loading requirements.

SUMMARY OF INVENTION

The present invention achieves technical advantages as a modular staircase system which may be configured to form a curved staircase, support extremely heavy finishing materials, having high design tolerances, and which can be constructed at a relatively moderate cost. A plurality of stair modules are configured to secure to one another to form a complete staircase system, each module having an elaborate framed stringer of significant strength and moderate weight, configurable to create eloquent floating staircases at an affordable cost. The stringers may be formed of steel tread flanges and riser flanges to form a steel framed stringer. The tread flanges and riser flanges may form a rectangular frame defining an opening, adapted to receive an outer fascia member, and support a riser and tread extending therebetween. This metal framed stringer can be designed to be curved to extremely tight tolerances and support extremely heavy loads, and easily assembled as a complex staircase at the fabricator, disassembled for convenient transport, and reassembled at its intended location with moderate effort. Because the steel stringers are framed, the cost of materials is reduced without sacrificing strength, and the curve can be designed to a tight tolerance using computer aided tooling equipment. Staircases designed according to the present invention can realize up to an 40% savings in materials and 50% savings in labor compared to conventional staircase systems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a planar view of a modular curved staircase system according to one preferred embodiment of the present invention;

FIG. 2 is a top view of the staircase system of FIG. 1 with the risers and treads removed to expose the framed stringers in modular construction;

FIG. 3 is a view of the underside of the staircase system shown in FIG. 2 detailing the laterally extending t-astragals extending between the stringers, as well as the hardware for securing one modular stair section to the next;

FIG. 4 is an enlarged view of one modular stair section of the staircase shown in FIG. 1 with the treads and risers removed;

FIG. 5 is a perspective view of a single stair module with the riser and tread portions removed;

FIG. 6 is a perspective view of a single stair module with a unitary riser and tread portion adapted to and supported by the framed stringers;

FIG. 7 is a perspective view of a single stair section with a unitary riser/tread adapted over each step and supported by the framed stringers;

FIG. 8 is a perspective view of a staircase system according to a second preferred embodiment including modular stair sections and a plurality of modular landing sections; and

FIG. 9 is an enlarged view of a landing section extending between two modular stair sections shown in FIG. 8.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Referring now to FIG. 1, there is generally shown at 10 a modular staircase system according to one preferred embodiment of the present invention. System 10 is seen to be comprised of a plurality of stair sections generally shown at 12 assembled and secured to one another to create a floating staircase with continuous ascending steps generally shown at 14. Each step 14 has a riser portion 16 and a tread portion 18, as shown. In this preferred embodiment, each stair section 12 has three steps 14, although more or less steps could be included in the stair section 12 as desired and as a function of the overall staircase design. Staircase system 10 derives technical advantages in that a complex staircase system can be achieved utilizing modular stair sections, each section being tooled to very tight tolerances, configured to support great weight including premium stair materials including cast stone, marble and granite, as well as itself, at a relatively moderate cost.

Referring now to FIG. 2, there is shown staircase system 10 with each of the risers 16 and treads 18 removed therefrom to expose the framed stringers 20 adapted to support and receive the plurality of risers 16 and treads 18. The stringers 20 are preferably comprised of high strength metal material such as cold rolled steel so as to be adapted to support the staircase system 10 itself, as well as the extremely heavy premium materials supported thereon. Each stringer 20 of each section 12 is seen to comprise of a plurality of framed portions generally shown at 22 forming a rectangle and a space 24 therewithin. A curved planar fascia member 26 is secured to an inner and outer portion of the framed portions 20 to collectively form the inner and outer stringers 20, as will be discussed in more detail shortly. Also shown in FIG. 2 is each of the stair sections 12 secured to another stair section 12 either above the upper step or below the lower step, as shown. Each stair section 12 is seen to include a laterally extending frame member 30 configured to be secured to the opposing frame member 30 of the adjacent stair section 12. The opposing frame portions 30 of adjacent sections are secured to one another, such as using fasteners or welding, as generally shown at 32.

Referring now to FIG. 3, there is shown an enlarged view of the staircase system shown in FIG. 2 further detailing the securing mechanisms 32, shown as bolts and nuts, securing one step section 12 to the next. Also shown is a plurality of laterally extending frame members 40, commonly referred to as t-astragals, adapted to receive a bottom fascia (not shown) in a flush relationship.

Turning now to FIG. 4, there is shown an enlarged view of the lower step section 12 shown in FIG. 2 with the tread and riser portions removed to expose the framed stringer portions 22. Each stringer 20 is comprised of a plurality of riser flanges 42 and tread flanges 44, each shown to be comprised of a planar strip secured to one another, such as by welding. More specifically, a stringer flange 44 is seen to extend the width of two steps, with a first riser flange 42 extending upwardly from the mid section thereof, and also downwardly from the mid section thereof to form collinear aligned riser flanges in a “T” configuration. These members are preferably welded together and form the structurally rigid rectangular frame portion 22. The inner and outer fascia member 26 are each preferably comprised of curved planar steel stock welded to the riser flanges 42 and tread flanges 44 to collectively form the framed curved metal stringer 20.

Also shown is a plurality of openings linearly defined in the riser flanges 42 so as to facilitate securing a finished riser portion thereto using fasteners (not shown). The upper tread flange 44 forms the tread support configured to receive and secure a tread, comprised of a planar member, such as wood, steel, plywood, but also can receive and support extremely heavy materials including cast stone, marble and granite, as well as elaborate railing systems including cast stone and wrought iron materials.

Advantageously, the framed stringer portions 20 can be configured with precision tooling to very tight tolerances, even when curved as shown. As previously mentioned, curved staircases are the most difficult staircases to create given the material characteristics themselves, such as when under load, heated, or bent. When each step section 12 is ultimately integrated to form the complete staircase 10, the precision of each step section 12 creates a very precision staircase system 10. Advantageously, the need for a continuous extremely thick stock of steel as a stringer is eliminated, greatly reducing the cost of the stair system, while maintaining mechanical integrity. Further, if there is a misalignment at installation, only one section needs to be reworked or re-fabricated.

Referring now to FIG. 5, there is shown another view of the stair section shown in FIG. 4 by itself.

Referring now to FIG. 6, there is shown the single stair section with a unitary riser and tread portion 50 extending between the respective stringers 20 and secured to both the riser flanges and tread flanges, such as by welding. This unitary riser/flange member 50 may, if desired, receive the finished tread member and riser member, such as both mortar compound and the tread itself. The unitary tread/riser member further provides structural integrity in three dimensions for each step section 12.

Referring now to FIG. 7, there is shown the completely assembled step section 12 with the unitary riser/flange sections 50. A pair of lower flanges 46 are also shown secured to the underside of the framed stringers 20, as shown.

In one preferred embodiment of the present invention, for purposes of illustration without limitation thereto, each step section 12 may be configured or comprised of ¼ inch CRS, whereby the tread flanges may be 3 inch W× 3/16 inch CRS. The lower stringer flange may be 3 inch W× 3/16 inch CRS, and the tread/riser plate may be 3/16 inch CRS. The t-astragal may be 14 gauge with a 3 inch width, and a 1 inch vertical rise having a thickness of ⅛ inch. Non-structural components for all tread surfaces may be, for instance, 1⅝ mortar layer, 1¾ inch marble layer, and ¾ inch sheet rock and plaster for the facade. With these design specifications, the staircase of FIG. 1 meets the structural design loads for 1- and 2- family dwellings manual, prepared by the US Department of Housing and Urban Development Office of Policy Development and Research. For instance, the staircase system 10 adequately supports a concentrated live load of 300 pounds (or 40 PSF, whichever is greater) assumed to act directly in the middle of each sub-tread to simulate a worst-case scenario. Each sub-tread, when analyzed individually, meets these requirements.

Referring now to FIG. 8, there is shown another, more complex staircase system 60 configured according to the present invention. As shown, staircase system 60 includes a plurality of step sections 12, as well as a plurality of landing sections 62 interposed between a pair of step sections 12 and secured thereto to create an elaborate floating staircase. In this design, the inner and outer welded composite sheet metal stringers are comprised of 3/16 inch CRS, as is the tread/risers. Referring to FIG. 9, there an enlarged view of the lower landing 62 designed to support floating conditions when configured with marble and mortar finishing materials. It can be appreciated, in view of FIG. 8, that this elaborate staircase system 60 has a significantly reduced staircase dead weight, including the steel materials as well as the marble and mortar finishing materials, that is extremely moderate considering the size and complexity of the stair system 60, while still meeting the load requirements established by the US Department of Housing and Urban Development Office of Policy Development and Research. Further, this staircase integrity is also verified by the SolidWorks® program created by SolidWorks Corporation of Concord, Mass., and is verified by a registered professional engineer.

To those skilled in the art of complex staircase systems designs, which is truly a skilled art, they will appreciate the numerous advantages of the present invention. The modularity of the staircase system is just one technical advantage of the present invention, coupled with the fact that extremely precision high-load staircases can be realized at a fraction of the cost of those comparable systems created with continuous stringers that are extremely expensive, difficult to manufacture, and difficult to integrate, particularly in close locations. Moreover, the engineered staircase system can be manufactured prior to delivery and assembly at the stairs ultimate location to verify integrity, tolerances, and perform overall quality analysis. Further, there is a tremendous time savings in both the manufacturing time for such a staircase system, as well as the installation time. Consider the fact that the staircase system shown in FIG. 1 can be easily installed by skilled labor into a home in one day without elaborate scaffolding or huge labor cost. Further consider that a floating staircase of intricate design, high load, and that is aesthetically pleasing to discriminate homeowners and guests, the numerous technical advantages of the present invention can be realized. Should one step section 12 ever need to be repaired or replaced, the stair case can be easily and quickly disassembled, with the replacement section integrated therewith at a very nominal cost. It can be further appreciated that despite all the numerous technical advantages in CAD design, complete tooling and design experience, a delivered staircase system 10 may not always perfectly fit in its intended environment. In such cases, the upper section 12 may be redesigned to provide a high tolerance fit between the rest of the staircase system 10 and the upper landing without having to replace the entire staircase or having to rework the entire staircase. Considering the cost of materials and labor, and the extremely competitive environment for which staircase designers compete, the numerous advantages of the present invention provide a highly desirable system, and allow staircases that are truly of art to be created.

Though the invention has been described with respect to specific preferred embodiments, many variations and modifications will become apparent to those skilled in the art upon reading the present application. It is therefore the intention that the appended claims be interpreted as broadly as possible in view of the prior art to include all such variations and modifications.

Claims

1. A stair system comprising:

a plurality of steps each having a riser portion and a tread portion, each of the steps having a first end and a second end;

a first stringer secured to the first end of each said step, the first stringer extending generally transverse to each of the steps; and

wherein the first stringer is comprised of frame elements defining stringer spaces therebetween, and further comprises a face flange secured to the frame elements proximate the stringer spaces.

2. The stair system as specified in claim 1 wherein the frame elements comprise at least two stringer flanges extending generally parallel to each other.

3. The stair system as specified in claim 2 further comprising at least one riser flange extending between the two stringer flanges, wherein one of the stringer flanges is positioned closely proximate one of the step tread portions.

4. The stair system as specified in claim 3 wherein the riser flange extends transverse from a midsection of one of the stringer flanges to the other stringer flange.

5. The stair system as specified in claim 4 further comprising at least two said riser flanges extending between the two stringer flanges to form a generally rectangular stringer frame portion.

6. The stair system as specified in claim 5 wherein the face flange is secured directly to the two stringer flanges and the two riser flanges.

7. The stair system as specified in claim 5 further comprising a lower flange extending beneath, and secured to, a lower portion of the stringer frame portion.

8. The stair system as specified in claim 2 wherein the face flange is generally planar.

9. The stair system as specified in claim 2 wherein the stringer flanges are generally planar.

10. The stair system as specified in claim 2 wherein the riser flanges are generally planar.

11. The stair system as specified in claim 2 wherein the face flange has a major outer surface that is curved.

12. The stair system as specified in claim 2 wherein the stair system has a securing portion configured to securely join the stair system to another said stair system.

13. The stair system as specified in claim 2 wherein the steps of each said secured staircase systems are in line with each other to form an ascending or descending stair.

14. The stair system as specified in claim 2 wherein the stair system has a securing portion configured to securely join the stair system to a landing member.

15. The stair system as specified in claim 2 wherein the securing portion comprises an opening configured to receive a fastener securingly extending to another said stair system.

16. The stair system as specified in claim 2 wherein the first stringer further includes a railing mounting portion configured to receive and support a railing.

17. The stair system as specified in claim 2 wherein the railing mounting portion includes a plurality of openings configured to receive a railing system.

18. The stair system as specified in claim 2 wherein the first stringer is comprised of a metal material.

19. The stair system as specified in claim 2 wherein the riser portion and the tread portions are comprised of a planar metal material.

20. The stair system as specified in claim 2 wherein the riser portion and tread portion are comprised of metal strips.

21. The stair system as specified in claim 2 wherein the face flange comprises a singular planar piece of metal.

22. The stair system as specified in claim 19 wherein the riser portion is a riser extending the width of the tread.

23. The stair system as specified in claim 19 wherein the tread portion is a tread extending the width of the tread.

24. The stair system as specified in claim 19 wherein the riser portion and the tread portion each extend the width of the tread and are also a unitary member.

25. The stair system as specified in claim 22 wherein the riser is curved.

26. The stair system as specified in claim 22 wherein the thread is curved.

27. The stair system as specified in claim 1 further comprising a t-astragal extending from the first stringer.

28. The stair system as specified in claim 18 wherein the first stringer is comprised of steel.

29. The stair system as specified in claim 28 wherein the stringer frame elements are welded together.

30. The stair system as specified in claim 4 wherein the at least one riser flange is generally perpendicular to one of the stringer flanges.

31. The stair system as specified in claim 2 wherein at least one of the stringer flanges extends the width of two said steps.

32. The stair system as specified in claim 2 wherein the stringer flanges extend parallel of one said step.