Overview

Philadelphia’s City Hall building is one of the nation’s most recognizable historic buildings. Completed in 1901, the 548 ft. tall building is the largest load-bearing masonry building in the world and, at over 1 million s/f, also the largest municipal building in the United States. Philadelphia fire code ordinance changes now require all non-residential buildings over 75 ft. in height to have sprinkler systems. Over the last decade, City Hall has internally been phasing sprinkler compliance across its 700+ rooms. We were hired to design the sprinkler system in the final 29 rooms, due to the construction complexities and architectural intricacies of the rooms, which included elegant courtrooms, the Mayor’s Reception Room, and the Law Library.

Challenges

The building presented challenges to the sprinkler design in many ways. High ceilings and masonry vault floor construction allowed virtually no access to space above ceilings. Incomplete, outdated, and missing construction drawings compounded the fact that construction techniques and technologies changed over the building’s 30 year construction period, removing construction uniformity between floors. Physical construction challenges were supplemented by incredibly ornate gilded ceiling coffers and lighting.

Solutions

Each room’s sprinkler solution was unique. Through various methods of surveying, including utilizing a boroscope, and working with the fire marshal, we were able to design compliant sprinklers with minimal aesthetic impact on all of the rooms. Most rooms utilized concealed piping and sprinkler heads, which were color matched to the ceiling. Variances were obtained to install exposed wall-mounted sprinklers in some more ornate rooms. Exposed below ceiling sprinklers were utilized in a few areas in which concealment was not feasible.