Assessing the Cost of Seismic Retrofit

Cost plays a critical role in selecting the most appropriate retrofit measure. It is always best to undertake retrofit measures before an earthquake occurs, when options are available for strengthening existing members. Once damage is done, the cost will be substantially higher and finding engineers, architects, and contractors available to do the work on a constricted schedule will be more difficult.

Planned seismic retrofit work may add between $10 and $100 per square foot to the cost of rehabilitation work depending on the level of intervention, the condition of the building, and whether work will be undertaken while the building is occupied. Costs can exceed several hundred dollars a square foot for combined restoration and seismic upgrade costs in major public buildings, in order to provide a level of structural reinforcement that would require only minor repairs after a major earthquake. But maintenance and incremental improvements to eliminate life-safety risks are within the cost realm of responsible upkeep.

Each property owner has to weigh the costs and benefits of undertaking seismic retrofit in a timely manner. Owners may find that an extended engineering study evaluating a wide range of options is worthwhile. Not only can such a study consider the most sensitive historic preservation solution, but the most cost-effective one as well. In many cases, actual retrofit expenses have been lower than anticipated because a careful analysis of the existing building was made that took the durability and performance of existing historic materials into consideration. Most seismic retrofit is done incrementally or incorporated into other rehabilitation work. In large public buildings, seemingly expensive "high-tech" solution such as installing foundation base isolators can turn out to be justified because significant historic materials do not have to be removed, replaced, or replicated. The cost for a fully retrofitted building can offset the potential loss of income, relocation, and rebuilding after an earthquake. Without careful study, these solutions often are not evaluated.

Some municipalities and states provide low-interest loans, tax relief, municipal bonds, or funding grants targeted to seismic retrofit. Federal tax incentives for the rehabilitation of income-producing historic buildings include seismic strengthening as an allowable expense. Information on these incentives is available from the State Historic Preservation Office. It is also in the best interest of business communities to support the retrofit of buildings in seismically active areas to reduce the loss of sales and property taxes, should an earthquake occur.