Historic Skylight

The building’s three-story atrium features a 40-foot by 60-foot skylight, allowing natural light to flood in, illuminating the rich and highly articulated interiors. The original skylight was fabricated nearby in Chelsea, N.Y., and the monitor consists of two separate glazed assemblies with an interstitial space in between. While the outer assembly faces the sky and provides protection from the weather, the interior glass layer, or laylight, is seen by the public from within the atrium, and is treated in a highly ornamental fashion. Additionally, the laylight provides code-required occupant protection from potentially falling glass. The gable-shaped monitor projects from the roof, with glass panels originally supported by a copper frame structure with a ridge at its peak. There are 10 clerestory windows on the vertical sides where the skylight drops to a walkway that stretches around its perimeter. The walkway extends along the built-in gutters at two sides and consists of hexagonal glass block set within cast iron panels. The laylight within the atrium is comprised of hundreds of translucent glass panels set in an ornamental bronze-clad cast iron frame forming a monumental barrel vault.

The skylight began leaking in the 1990s, but due to the constant use of the building, rehabilitation was postponed. By the time restoration began, the atrium’s grandeur was diminished by the damaged and grimy skylight, and there was extensive damage to adjacent materials, such as marble and plaster. The renovation team, led by Urbahn Architects, New York City, removed the entire outer monitor system and replaced it with a new copper-anodized aluminum frame to emulate the original copper frame cladding. The team oversaw the fabrication of a new aluminum frame to hold the glass panels, and several new copper elements were fabricated to match the originals, including leaders, gutters and a ridge vent.

For the laylight, Urbahn and historic conservator Jablonski Building Conservation Inc. (JBC), New York City, developed a procedure that called for removing the glass panels to facilitate the restoration of the leading that holds the glass in place, as well as provision of new glass to replace missing or broken panes. Additionally, the bronze cladding was stripped of all coatings, cleaned and refinished in situ.

To address the inherent vulnerability of the glass block walkway to water infiltration, the design team designed a new protective assembly including laminated glass protecting the glass blocks with new, durable aluminum panels as a walking surface, all within a new metal frame system. The original hexagonal glass blocks, which are 1 1/2-inch-thick by 3 1/2 inches wide, were replicated with groups of blocks forming 24 glass panels running on two sides of the skylight.

“Working within a cherished historic edifice such as Surrogate’s Court required a team that is attuned to the aesthetics, materials, and building practices of another age, as well as well versed in both the limitations and advances of modern construction technologies,” explains Rafael Stein, AIA, principal at Urbahn.

Extensive corrosion of the cast iron frames required Gillinder Brothers Inc., Port Jervis, N.Y., to cast new hexagonal glass blocks to match the originals, including an embossed snowflake pattern on the surface. Wemco Casting LLC, Bohemia, N.Y., fabricated the new cast iron frames. EverGreene Architectural Arts, Brooklyn, N.Y., repaired the plaster on the lunettes before they were painted to match the Siena walls and columns, and stripped the bronze enclosures of all finishes before cleaning.