Stair Hanger Inversion for Concealed Rim Joist Connection

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Solution Overview

Problem

Existing methods for connecting stair stringers to a rim joist lack a structurally rated, concealed, and accessible solution, often requiring additional materials and time, with standard joist hangers not tested for this specific application and not providing a concealed connection.

Innovation Solution

A pair of mirror-image stair hangers or a reversible hanger system that connects stair stringers to a rim joist from the front side, using nail-receiving openings and flanges to provide a concealed and structurally rated connection, suitable for deck construction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If standard joist hangers with a sloped seat are used, then the connection is structurally rated and tested, but the connection is not concealed and the flanges are visible

Engineering Contradiction:

Improvestructural ratingVSAvoidconcealed connection

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The hanger design inverts the traditional joist hanger configuration by positioning the flanges to face upward instead of outward, allowing them to be concealed beneath the stringer while maintaining structural integrity and load-bearing capacity

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of operation

If nails or screws are driven through the back side of the rim joist, then the connection can be made, but the connection is not structurally rated and tested

Engineering Contradiction:

Improveconnection accessibilityVSAvoidstructural rating

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The hanger acts as an intermediary component that provides a structurally rated connection interface between the rim joist and stringer, eliminating the need for direct field modifications while ensuring tested and approved load-bearing capacity

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If additional building material is used to achieve the connection, then the connection can be made, but the process becomes time consuming

Engineering Contradiction:

Improveconnection strengthVSAvoidinstallation time

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The hanger integrates multiple functions into a single component: providing structural support, enabling concealed installation, ensuring structural rating compliance, and facilitating straightforward attachment to both the rim joist and stringer without requiring additional specialized materials

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS7631463B2Stair hanger

Publication Date: 2009.12.15 MITEK HOLDING INC

AI summary

A concealed connection mechanism for connecting a pair of stair stringers to the front face of a rim joist.