CONSULTING STRUCTURAL ENGINEERS SINCE 1941

Founded in 1941, Mackintosh & Mackintosh, Inc. is a structural engineering firm with a long-standing practice focused on the evaluation, rehabilitation, and adaptive reuse of existing structures throughout Southern California. The firm has developed particular expertise in the analysis and strengthening of historic buildings, including timber truss systems and unreinforced masonry (URM) construction.

Mackintosh & Mackintosh provides structural engineering services for a wide range of projects involving seismic retrofit, structural rehabilitation, and the integration of new structural systems into existing buildings. The firm is widely recognized for its work on historic timber roof systems, including bowstring trusses and other long-span wood structures, where preservation of the original structural character must be balanced with modern performance requirements.

A core component of the firm’s practice involves the evaluation of existing buildings subjected to structural distress or damage. Mackintosh & Mackintosh routinely performs structural damage assessments following seismic events, fire incidents, and other causes of structural degradation. The firm serves as the Engineer of Record for the development of repair and restoration plans, including the preparation of construction documents for fire-damaged structures and other compromised building systems.

The firm’s experience with fire-damaged buildings includes the assessment of structural capacity following exposure to elevated temperatures, evaluation of residual strength in wood, steel, and concrete elements, and the design of repair and replacement strategies that restore structural integrity while meeting current building code requirements. These services are often performed in coordination with building owners, insurance professionals, contractors, and public agencies.

Mackintosh & Mackintosh has extensive experience in the seismic retrofit of URM buildings and other existing structures subject to current code requirements. The firm’s work frequently involves the development of innovative load path solutions, including the use of collector elements, diaphragm strengthening, and the integration of Special Concentric Braced Frames (SCBF) and Special Moment Resisting Frames (SMRF) into existing construction.

Through decades of practice, the firm has built a reputation for providing thoughtful and practical structural solutions that respect the original construction while addressing the demands of modern building codes. Mackintosh & Mackintosh continues to support architects, owners, contractors, and institutions in delivering complex projects that require a high level of technical understanding and careful integration of new and existing structural systems.

Steven G. Provenghi, SE
Managing Principal
Mackintosh & Mackintosh, Inc.