The Pierre Hotel

WDP was engaged to perform a rope access critical examination of the building’s historic façade. The Pierre is subject to the directives of NYC LL11/98, “Façade Inspection and Safety Program” (FISP), requiring every building above six-stories in height to undergo hands-on façade inspections and filing of an acceptable inspection report classifying the façade conditions with the NYC Department of Buildings every five years.

Two of WDP’s SPRAT certified Professional Engineers performed the hands-on condition survey by rope access, thus offering flexibility and providing cost savings to the owner. Hammer sounding of cracked terra cotta masonry identified that some masonry elements were no longer fully engaged, and the building was classified as Unsafe. Subsequently, WDP developed façade repair documents to address cracked and spalling terra cotta and other masonry elements, as well as localized repointing and crack repair to mitigate excessive surface penetration, which has the potential to lead to accelerated façade deterioration.

Our professional team of envelope specialists includes Mr. Civitillo, who is certified by the NYC DOB as Qualified Exterior Wall Inspector (QEWI), and is intimately familiar with all types of enclosure systems and façades. Our understanding of the important differences between various systems, their material properties and intended functions allows us to design repairs with sensitivity to the subtleties required for each system. The Pierre Hotel façade is a mass masonry façade, consisting of a large number of glazed terracotta elements, which are most susceptible to deterioration resulting from weathering, freeze-thaw cycling, and rust-jacking of embedded structural steel due to prolonged moisture exposure.

As the initial investigation could only reasonably cover a representative portion of the façade, the repair design implemented a series of unit price repair details to allow for scaling the application of the typical repairs to portions of the façade that were not carefully examined. WDP worked closely with the NYC Landmarks Preservation Commission to gain approval for the repair approach and specific submitted products to preserve the historic fabric of the façade.

WDP has been providing façade condition surveys throughout the construction process. When a new scaffolding drop was rigged, WDP performed an initial drop survey with the contractor to identify and mark out unit price repairs as required to correct unsafe and SWARMP conditions. The primary goal of the repair program is to correct conditions that may pose an immediate hazard to life safety. However, the program is designed with the secondary goal to improve durability by reducing pathways for moisture intrusion that can lead to accelerated deterioration.

At several locations and particularly at corners of the building, cracking in terra cotta is prevalent, thus WDP has directed test cuts to observe and measure any steel column section loss and evaluate the need for structural repairs. WDP’s in-house structural engineering capabilities have proved beneficial in that we have easily transitioned from façade repairs to structural evaluation and back. When a probe was uncovered, we used a combination of calipers and ultrasonic thickness measurements to quantify the remaining section properties of the exposed steel. With this information we are able to calculate the remaining section capacity and compare it against the original section’s reserve capacity. For the steel locations requiring strengthening or replacement, our structural engineers are able to develop creative connection details to replace original riveted connections without altering the capacity or structural behavior of the overall system. Weldability analysis was performed on the original steel to verify that the chemical composition of the Carnegie steel sections will lend itself to modern steel sections and welding electrodes.