elemental » Construction Update

Construction Update: Shepard Hall TSRU Models

administrator — Wed, 31 Mar 2010 21:08:25 +0000

Fabrication has begun of the models needed for the production molds for the thin-shell replicas that will replace the deteriorated terra cotta. Together with the previous nine phases, more than 60,000 pieces have been replaced making this by far the largest historic reconstruction of its kind in the world.

The thin-shell approach was developed in 1986-87 by Elemental (then The Stein Partnership) as a means to rebuild the failing structure on an accelerated schedule and still allow for a cladding that accurately reflected the original material.

At the project outset, more than one third of the original terra cotta had already failed and been removed to protect the public safety. As a result, many of the sculptural elements required either partial restoration or total recreation based on the surviving fragments and old photographs. Here, from the first phase (1986-1991) are original grotesques with missing heads, replicas awaiting installation and the rebuilt turrets with the new thin-shell cladding.

This process continues today. Because the contemporary manufacturing processes offer a much higher level of precision than did the original, care is taken to introduce the imperfections that are characteristic of the terra cotta. These include tooling marks, irregularities on flat planes and slight variations in the characteristic “white” color from piece to piece. Depending on the level of deterioration of the original terra cotta, the process of obtaining models can vary from the direct use of terra cotta originals as new molds, to partial reconstruction of damaged terra cotta and fabrication of complete recreations based on historic photographs and interpolations from other similar pieces on the building.

Here, models have been fabricated based on typical profiles found throughout the building

In other cases, terra cotta that had suffered minimal damage serves as models, such as these florettes

This unique grotesque from the building, missing pieces of his nose and and fingers, was carefully removed from the building

and restored to serve as a model for the new GFRC replacement.

When the models are finished, rubber-lined production molds will be created. The thin shell replacement units (TSRU) are then fabricated using a sprayed glass fiber reinforced cementitious system, about three quarters of an inch thick. The description of the process will continue as the project progresses.

Stay tuned for continued updates from the field.

Construction Update: Shepard Hall Entry Ramp & Facade Work

administrator — Thu, 18 Feb 2010 21:57:56 +0000

Entry Ramp Takes Shape

Central to the entry redesign is the reconstruction of the original ground floor entrance. In addition to the salvaged schist stone wall, concrete retaining walls form the stair opening leading down to the original lower level stone arch entry. Earth and gravel fill are compacted to serve as a supporting base for the new concrete stair slab.

Facade Reconstruction Underway

Scaffolding has been erected and selective demolition & removals have begun on the main building. The first step of the facade reconstruction is the selective removal of existing terra cotta sculpture to serve as models for new Glass Fiber Reinforced Concrete (GFRC) replicas.

A rigorously tested thin-shell GFRC, strong, light weight and durable, has been the material for all the terra cotta reconstruction. The entire reconstruction, totaling over 65,000 pieces, is currently the largest GFRC reconstruction project in the world.

Following careful removal of the representative sculptural pieces, demolition of the remaining terra cotta will begin.

Steel lintel Investigation

Meanwhile, the demolition of the existing terra cotta window surrounds exposes the original steel lintels that support the window openings. Each steel lintel is inspected to determine its structural viability. Where possible, salvaging the original steel is preferred.

Schist Stone Sounding

Local Manhattan Schist stone is the primary façade material of Shepard Hall as well as the other campus buildings originally designed by George Post. Through a process called “sounding,” each stone on the building is struck with a mallet and the sound produced is an indicator of the stone’s integrity. Stones that sound “hollow” or are visibly damaged or deteriorated are marked by the design team for replacement.

Stay tuned for continued updates from the field.

Construction Update: Shepard Hall, concrete underpinning

administrator — Mon, 02 Nov 2009 19:37:09 +0000

As construction continues, efforts to utilize the original schist stone entry ramp wall that was recently unearthed continue to make progress. Concrete underpinning (for an explanation of underpinning, click here) along with new steel reinforcement, will allow the original schist stone wall to be incorporated into the new entry design. Meanwhile, as the entry ramp work continues, Elemental Architecture and the team are preparing to commence full scale reconstruction efforts on portions of the main building itself. Stay tuned for continued updates from the field.

Construction Update: Shepard Hall Original Entry Wall Fully Revealed

Tom Abraham, AIA — Thu, 17 Sep 2009 17:38:22 +0000

Along with the recently unearthed entry stairs a major portion of the original entry wall has been unearthed. Following inspection, the team is now evaluating how this remnant of the original entry can be incorporated into the reconstruction. The wall, constructed of Manhattan schist likely from the building site, was buried under fill during a mid-twentieth century alteration. As part of the reconstruction efforts to the entire building, a new entry in keeping with George Post’s original entry is being created. Stay tuned for continued updates from the field.

Construction Update: Shepard Hall Original Entry Stairs Revealed

Tom Abraham, AIA — Thu, 03 Sep 2009 17:51:02 +0000

As demolition and excavation progress continues for the newly designed building entry, a startling discovery: the original entry stairs built in 1907, long believed to have been demolished, are found buried under earthwork fill below the recently removed concrete ramp. Along with the stairs a significant portion of original schist stone wall is also uncovered. Elemental and the construction team are now evaluating if portions of the original elements can be incorporated into the new entry design.

Construction Update: Shepard Hall Reconstruction Kicks-off

Tom Abraham, AIA — Thu, 28 May 2009 13:30:40 +0000

The 9^th & 10^th phases of the award-winning historic reconstruction of Shepard Hall at the City College of New York has officially begun. The project, which includes the replacement of nearly 8,000 pieces of failing terra cotta sculpture ornament with new glass-fiber reinforced concrete replacement units and a new main entrance to the building, is expected to be complete by May 2011. Stay tuned for regular construction progress updates from the field.