Modular Stair Stringer Assembly with Alignment Brackets
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Solution Overview
Problem
Conventional stair stringer construction is labor-intensive and prone to errors, with existing prefabricated solutions lacking flexibility to accommodate variations in building environments and requiring careful measurement, which increases installation time and potential for mistakes.
Innovation Solution
A stringer assembly comprising a support element, brackets with rise and run indicators, and alignment elements that allow for accurate spacing and squaring of brackets, along with a temporary tread system and preassembled tread and riser combinations to facilitate efficient and variable construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional stringer construction with separate marking and cutting of each triangular portion is used, then the stringer can be custom-fitted to specific rise and run dimensions, but the construction requires great deal of labor and presents numerous opportunities for error and injury
Solution Approach 1:
The stringer is divided into modular components: a straight support element and multiple interchangeable triangular brackets. Each bracket is pre-cut with specific rise and run dimensions, allowing workers to simply assemble pre-fabricated pieces rather than measuring and cutting each section individually. This segmentation maintains adaptability while dramatically improving construction efficiency and reducing errors.
Solution Approach 2:
The triangular brackets are pre-cut and pre-marked with rise and run dimensions before delivery to the construction site. This preliminary preparation eliminates the need for on-site measuring and cutting operations, reducing labor time and minimizing opportunities for measurement errors while still allowing custom dimension selection from available bracket varieties.
2Productivity
If preassembled portions of stringers or prefabricated stairways are used, then some on-the-job calculating and cutting is eliminated, but the ability to accommodate for variables in the building environment is reduced
Solution Approach 1:
The system provides dynamic adaptability through interchangeable brackets with varying rise and run dimensions. Workers can select and swap brackets to accommodate different floor-to-ceiling heights, tread depths, and material thicknesses encountered in the field. This modular approach maintains installation efficiency while preserving the flexibility to adapt to building environment variables.
Solution Approach 2:
The straight support element serves as a universal base that can accommodate multiple types of triangular brackets with different dimensions. This universal interface allows a single support element to be used across various stair configurations, maintaining both installation efficiency and adaptability to different building conditions.
3Ease of manufacture
If L-shaped brackets with rise and run markings are used to construct a stringer, then most cutting issues are eliminated, but each bracket must be carefully measured before attaching, which increases installation time and leaves significant potential for error
Solution Approach 1:
The triangular brackets are designed with self-aligning features including pre-drilled attachment holes positioned to automatically align with corresponding holes in adjacent brackets and the support element. The brackets include integrated rise and run markings that self-register during assembly, eliminating the need for careful measurement and alignment operations while reducing installation time and potential for error.
Solution Approach 2:
Alignment pins or registration features act as intermediaries between brackets, automatically establishing correct positioning and spacing. These intermediaries transfer the alignment function from the installer to the component itself, eliminating measurement steps while ensuring accurate assembly.
4Strength
If a 2×12 piece of wood is used for the stringer, then sufficient structural thickness is available, but about one-quarter of the original piece is scrapped and the effective structural thickness is reduced to less than half
Solution Approach 1:
The stringer is segmented into a full-thickness straight support element and separate thin triangular brackets. The support element retains the complete structural thickness of the original 2×12 lumber, while the brackets are thin decorative or functional overlays. This segmentation preserves full structural integrity while eliminating material waste, as the brackets can be efficiently manufactured from smaller stock.
Data Source
AI summary
A stringer assembly includes a support element, a plurality of brackets and a plurality of alignment elements. The brackets are connected to the support element, and each bracket includes a rise indicator corresponding to a desired rise dimension and a run indicator corresponding to a desired run dimension. The alignment elements align the rise or run indicator on one of the brackets with the other of the rise or run indicator on an adjacent one of the brackets to space the brackets at a desired rise and run. The brackets each include a tread flange and a riser flange, such that a tread and a riser can be directly connected to each bracket. The brackets may include cutouts for a temporary tread system.