Location: Voorhees, New Jersey
Size: 650,000 sq. ft.
Masonry Used:65,000 sf. Exterior pressure-equalized open rainscreen. 27,000 sf. Interior Lightweight CMU walls. 12,000 sf. Exterior decorative CMU walls
Submitted by: Molly Construction Company
The hospital building is steel frame construction with structural stud backup with sheathing, waterproof membrane, rigid insulation backup walls with a thin stone pressure equalized open rainscreen façade. The stone rainscreen is the Arrisclip system by Arriscraft international installed with the Gridworx aluminum track anchor system by Precision Wall Systems, Inc. There is no mortar or joint sealant in the joints. The open rainscreen has horizontal aluminum and vertical polycarbonate components in the joints. The stone is made of calcium silicate from silica sand, lime and pigment. There is no Portland cement. Combined with the Gridworx aluminum track anchor system made from recycled aluminum, this façade is environmentally and maintenance friendly. This façade is also the first and only pressure equalized open rainscreen façade of calcium silicate stone to date.
Pressure equalizing is accomplished by compartmentalizing the cavity with internal baffles that keep air flow down to nominal two hundred square foot compartments in the facade. There were challenges in compartmentalizing the façade. Arriscraft provided details using vertical stainless steel flashing that is preinstalled starting at the face of the waterproof membrane. On top of the membrane is the “Z” channel stud system and rigid insulation. This needs to be installed prior to the Arrisclip/Gridworx system. In order to install the system using the metal flashing details the trades needed to visit the wall numerous times. The time consuming sequencing was driven by the union jurisdictions as follows starting with the backup walls. The carpenters install the framing and sheathing. The roofers install the waterproof membrane and compartment flashings. The carpenters install the Z channel studs and insulation and the masons install the Arrisclip/Gridworx stone facade.
The problems with preinstalling the compartment flashings are twofold. First, the design required the roofers to layout, “in space”, all of the horizontal and vertical components to the dimensions and tolerances to meet the stone shop drawings, weeks in advance of the Arrisclip installation. Secondly, assuming that the flashings were in the proper locations, they would not be durable enough to withstand the inadvertent damage inflicted by other trades working around thin gauge metal protruding from the backup walls during installation of the Z-channels, insulation and stone rainscreen veneer.
After analysis of the compartmentalization details and sequencing of trades, Molly was able to redesign the components to simplify the installation, remove the roofers from one construction sequence and put the mason in control of the compartmentalization of the rainscreen during the installation of the Arrisclip/Gridworx system. Continuous sheet metal was installed by the carpenters during the Z channel and insulation phase behind the control joints in the rainscreen. As the rainscreen was installed, weatherproof foam sheet was bonded to the sheet metal and captured between the Gridworx channels and control joint stones. This joint was then filled with silicone sealant to match the stone. This solution increased production of the façade construction, compressed the overall schedule, and improved the finish stone veneer by keeping the mason in control of the finished stone rainscreen system.
Architect/Designer: Bob Bonosho, AIA
Company: HGA Architects
Structural Engineer: Mark Debrauske, AIA
Company: HGA Architects
General Contractor: Bill Swanson, Project Executive
Company: Turner Construction - Philadelphia Office
Masonry Supplier: Craig Swirzon, Thin-Clad Manager
Company: Arriscraft International-Arrisclip system
Masonry Supplier: Stephen Lloyd, Principal
Company: Precision Wall Systems-Gridworx manufactruer
Masonry Supplier: Liz Billies, Sales Manager
Company: Consolidated Brick Company-Distributor
Masonry Supplier: Rocky Fizzano, Executive Vice President
Company: Fizzano Brothers Concrete Products-CMU manufacturer
Masonry Supplier: David Jaye, Sales Manager
Company: Trenwyth Industries-Decorative CMU manufacturer