Historic Preservation

Within the realm of rehabilitation and adaptive reuse of older structures, Silman has developed a special expertise in the engineering of historic buildings. We have worked on more than 400 individual landmarks recognized on federal, state, and city historic registers, as well as scores of other buildings of landmark quality. We have consulted on some of the largest preservation projects in the USA, such as Ellis Island ($160 million) and Shepard Hall at the City College of New York ($125 million). Our proficiency in the use of preservation techniques (non-destructive evaluation, remote monitoring, computer modeling, and composite construction) has aided our efforts in saving America’s architectural heritage.

Several of our engineers have formal education and degrees in accredited university historic preservation programs, while others have completed on-the-job training. We are fully conversant with the Secretary of the Interior’s Standards and Guidelines for Historic Preservation, as well as international standards, such as the Charter of Venice and World Heritage Sites recommendations. We have participated in writing Historic Structure Reports for a number of significant buildings.

Silman is thoroughly familiar with all of the structural materials found in historic buildings, including timber, masonry, plaster, concrete, iron and steel. Our work in new building construction has helped inform the efforts expended in restoration – we are leaders in the use of composite construction. The fusion of new, high-strength materials with old, where appropriate, has led to some innovative structural solutions, such as carbon fiber shell structures matrix bonded to a wood roof; steel tees bonded to rotted wood floor beams, steel flitch plates bolted to undersized timbers, steel plates bonded to buckled wood columns, and high strength prestressing tendons for reinforcing of existing historic concrete structures. Other modern materials are being considered, such as aircraft alloy of aluminum used for skylight mullions. Most important, all these solutions are governed by our understanding and appreciation for original fabric and the need to conserve it wherever possible.

We have used sophisticated computer modeling to understand better structural behavior of highly indeterminate structures. Three-dimensional and finite-element modeling are used to great advantage for numerous preservation projects. Complex seismic analysis resulting in retrofit plans have been conducted for several historic wood structures in the U.S., as well as ancient temples in Nepal.

Silman pioneered the use of non-destructive evaluation (NDE) techniques for historic buildings. In a $192,000 research partnership contract with the US Army Corps of Engineers, we studied the use of five technologies at the New York State Capitol: impulse radar, impact echo and ultrasonic pulse velocity, infrared thermography, electromagnetic detection and fiber optics. These methods have subsequently been used successfully at many historically sensitive projects. Silman’s utilization of remote sensing and monitoring is another technique used to great advantage in its preservation work.

Because sufficient funds are not always available to make necessary repairs immediately, Silman has developed a number of strategies to stabilize and temporarily protect historic buildings. Systems such as temporary shoring, weather barriers, netting, scaffolding, sidewalk sheds, cabling, and pinning give owners time to obtain the required money for permanent repairs. Programs designed to last as long as ten years have been developed, with excellent results. A companion methodology for permanent stabilization of historic ruins has also been developed; this is often the only alternate to a costly rehabilitation program.

Select preservation projects include the following: