Due to be completed this month, a four-story federal office building in Philadelphia is the first General Services Administration (GSA) project to require hard-metric concrete block and clay brick. That is, the masonry units had to be resized to meet round-number metric specifications rather than simply relabeled in metric dimensions, a practice known as soft-metric conversion. The 40,000-square-meter building is a steel-frame structure with concrete masonry backup walls and brick veneer. The project called for approximately 350,000 90x90x190 mm (nominal 100x100x200 mm) clay brick units; and 50,000 190x190x390 mm (nominal 200x200x400 mm) and 100,000 140x190x390 mm (nominal 150x200x400 mm) concrete masonry units. To achieve the nominal dimensions, masons used 10 mm mortar joints. PROJECT PROCEEDED SMOOTHLY Although productivity dipped somewhat in the early stages--as contractors, tradespeople, and suppliers learned to think and work in metric--the job proceeded smoothly overall. JOB CHALLENGES There were some challenges to overcome. Getting workers to converse and think in metric was one of them. To shorten the learning curve, the contractor purchased metric tape measures and rulers, and insisted that the workers use them. Material ordering also presented a challenge. Since the federal office building is the only hard-metric project in the area, the contractor had to avoid ordering too many of the custom-made block and brick, which couldn't be used anywhere else.