Client: Sterling Miller Designs
Location: Private Residence
Project Brief: ASR provided engineering support for a seven-story spiral staircase, enabling precise Corian cladding installation through as-built modeling, vibration mitigation, and installation engineering.
ASR’s Role: Primary engineering partner providing as-built CAD modeling, structural and vibration analysis, thermal assessment, mounting strategy development, and installation engineering support.
Project Summary
ASR provided specialized engineering support for the installation of Corian cladding on a seven-story spiral staircase within a private residence. The structural steel staircase had been designed and installed by others prior to ASR’s involvement. ASR was engaged to support the architectural vision by enabling the precise fabrication and installation of Corian panels onto an existing steel structure with significant geometric complexity and tight aesthetic tolerances.
ASR worked closely with Sterling Miller Designs to bridge the gap between architectural intent, as-installed conditions, and constructability. The scope included as-built modeling based on 3D scan data, detailed CAD development, vibration and stiffness analysis, thermal expansion assessment, and the design of installation tooling and methodologies to achieve a continuous, monolithic Corian surface consistent with the architect’s renderings.
Engineering Scope & Key Constraints
The engineering challenge centered on fitting rigid architectural cladding onto an existing steel spiral staircase spanning multiple floors, where accumulated construction tolerances and structural flexibility could not be accommodated through conventional fabrication methods. Key constraints included:
- Installation onto an as-built steel structure with cumulative tolerance stack-up
- Architectural requirements for a smooth, continuous Corian surface with minimal visible joints
- Multi-story geometry with no central support column, resulting in structural flexibility
- Dynamic behavior perceptible to occupants across multiple levels
- Thermal expansion and contraction of Corian relative to steel
- Avoidance of expansion joints while preventing cracking or long-term damage
- Installation sequencing and tooling requirements for a confined interior environment
Meeting these constraints required a tightly integrated approach combining field measurement, advanced analysis, and fabrication-aware design.
ASR’s Approach
High-Resolution 3D Scanning and As-Built Modeling
To accurately capture the geometry of the installed steel staircase, a Leica 3D Disto scanner was used by others to perform a high-resolution scan of the as-built structure. ASR received the resulting scan data and imported it into CAD to develop a high-fidelity digital model representing the exact installed condition of the staircase.
Analysis of the scan-derived model revealed that the architect’s original Corian geometry would not fit the installed steel without visible gaps or misalignment due to cumulative fabrication and installation tolerances. Using the measured data, ASR developed a method of fitting the Corian drum axis to the scan-defined reference points, minimizing cumulative error while keeping deviations visually imperceptible.
ASR provided targeted guidance identifying localized areas where limited grinding of the steel was required, along with selective modifications to the Corian design, such as recessed lap joints in problem regions. This approach minimized rework, avoided extensive modification of the steel structure, and resulted in a smooth, continuous Corian surface that closely matched the architect’s renderings.
Vibration, Stiffness, and Dynamic Analysis
During the project, it was observed that motion at upper levels of the staircase could be felt at lower levels, indicating significant structural flexibility and dynamic coupling across floors. ASR conducted a vibration study and stiffness analysis to evaluate the dynamic behavior of the staircase and its interaction with the surrounding residential structure.
A detailed finite element model was developed to:
- Identify dominant vibration modes and resonant behavior
- Evaluate global and local stiffness of the staircase across multiple levels
- Assess boundary condition stiffness provided by adjacent floors and landings
The absence of a central support column resulted in the staircase behaving as a large, flexible spring. Field observations were correlated with analytical results to validate the model and confirm the governing modes of vibration.
Based on these findings, ASR engineered targeted structural reinforcements to stiffen structures, reducing dynamic amplification and mitigating perceptible vibration from occupant foot traffic. These modifications improved occupant comfort while preserving the architectural intent and ensuring compatibility with the Corian cladding system.
Thermal Expansion and Corian Attachment Strategy
ASR performed a thermal expansion and contraction analysis to evaluate differential movement between the Corian cladding and the steel substrate across expected temperature ranges. The objective was to prevent cracking, adhesive failure, or stress buildup without relying on visible expansion joints.
Using the high-fidelity as-built CAD model derived from the 3D scan data, ASR developed panel-specific shimming and mounting methodologies to accommodate differential movement while maintaining precise alignment. These strategies were tailored for each Corian panel based on local geometry, orientation, and boundary conditions.
This approach enabled a monolithic Corian appearance while preserving structural integrity, material performance, and long-term durability.
Fabrication Tooling and Installation Engineering
In addition to creating final CAD models of the Corian panels and handrails, ASR designed custom tooling and fixtures to support fabrication and installation.
ASR also developed installation methodologies and sequencing guidance to manage deflection, alignment, and load transfer during installation, ensuring that field conditions remained consistent with analytical assumptions.
Collaboration and Verification
ASR worked closely with Sterling Miller Designs, fabricators, and installation teams throughout the project. Engineering recommendations were continuously refined to balance architectural intent, as-built conditions, and constructability.
The combination of scan-derived modeling, validated analysis, and fabrication-aware engineering allowed potential issues to be resolved proactively rather than reactively during installation.
Outcome
ASR enabled the successful installation of Corian cladding on a seven-story spiral staircase that would not have been feasible using conventional design assumptions. The final result achieved a smooth, continuous architectural surface with no visible gaps, minimal modification to the existing steel, and long-term durability.
This project demonstrates ASR’s ability to support architects and designers on highly complex interior architectural features—particularly where precision cladding, structural flexibility, and aesthetic expectations intersect. ASR’s combination of as-built modeling, advanced analysis, and practical installation engineering allowed the architectural vision to be realized without compromise.
