Shoring Considerations in Existing Buildings

Construction in existing buildings can encompass repair, restoration, horizontal and/or vertical expansion, modification of architectural programs, or changes in occupancy classification to achieve project goals. Typically, the project’s Registered Design Professional (RDP) develops construction documents for the final design configuration which only show permanent design conditions and do not consider temporary loading and support conditions. Contractors are responsible for means, methods, and sequences of construction to achieve the final design intent, allowing them to complete the work in accordance with their own preferences and capabilities.

Some projects require temporary structural modifications, while others may rely on the existing structure to support construction activities. Temporary shoring is required when existing structural elements do not possess sufficient strength to support construction loads. Shoring, typically, is viewed as props, posts, beams, or other members installed temporarily to provide support to an existing building element during construction.

The RDP generally does not provide shoring design with the final design documents as it is not part of the permanent structural system. The responsibility for temporary conditions is left to the Contractor, who engages a Specialty Structural Engineer (SSE) to serve as the Design Professional in Responsible Charge of designing and specifying shoring systems. The SSE must consider many factors when designing shoring including, but not limited to, temporary loads during construction, facility use during the work period, appropriate types of shoring, the available strength of the existing structure, including any modifications as part of the work, and the Contractor’s sequences, methods, preferences, and capabilities. This article presents several of these considerations and the challenges they can create for the SSE, with examples of how these obstacles were addressed on previous projects where the authors acted as the SSE for shoring design.

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