Insulated Metal Panels for Wall and Roofing Retrofits
RE-ROOFING AND RECLADDING
So what are the drivers and benefits of replacing an existing building’s cladding and/or roofing system? “Overcladding an existing building can provide a new lease to the building’s life/aesthetic and also provide upgrades to the building’s air tightness, air quality, and thermal/energy performance requirements,” states Duc Vo, LEED Green Associate, Senior Project Manager, Curtainwall Production Coordinator, Sunrise Erectors, Canton, Mass.
“As commercial buildings of the mid-20th century dwindle in market appeal, it’s often their facades that are showing their age,” explains architectural writer Katharine Logan in an Architectural Record article on building reclads. “Technical components fail; contemporary performance expectations outstrip what earlier materials and methods achieved; a change of program calls for a change of look; an aesthetic expression no longer appeals to the market. Meanwhile, the core structure typically remains sound, and the resources it embodies-energy and carbon emissions, money, and labor-retain their value. For a growing number of buildings, recladding can help reap fresh value from structure and site, improve performance and marketability, and launch a whole new lease on life,” she writes. Together with a fresh, updated look, building teams are afforded the opportunity to significantly upgrade building enclosure performance with thermal efficiencies, enhanced daylighting, acoustic performance, weather resistance, and resiliency.
Photo courtesy of ATAS International
For the adaptive reuse of an historical building into the Lafayette College Bushkill Commons in Eaton, Penn., IMPs provided the insulating properties and design flexibility that the college was seeking.
In many cases, buildings can remain occupied during many of these retrofit projects. When proper sequencing and construction methods are utilized, the building interiors are not exposed to the elements, and building owners don’t have the added expense of heating and cooling, or relocating their operations. Much of the existing building materials are retained and reused, significantly saving on resources, carbon emissions, and cost. This also limits the time and effort involved in hauling discarded materials to the landfill.
Another important aspect of these overcladding projects is the opportunity to preserve the building within the context of the neighborhood, and if applicable, protect the historic integrity of a building. “Preserving and retrofitting existing buildings is both good for the environment, and for our client’s bottom lines,” states Drake. For example, in a Construction Specifier article5 on overcladding for old masonry facades. Albert Aronov, AIA, Partner, RKTB Architects, New York, points out that many older government and school buildings are built with solid masonry bearing walls. Degraded over time, many of these buildings are drafty and leaking, with damaged brickwork and windows. “To address the deleterious effects of time, weather, and full occupancy on masonry school buildings, overcladding has emerged as a valuable strategy,” he writes. When overcladding masonry structures with IMPs, for example, these upgrades can capitalize on the masonry’s existing thermal mass. Incentivizing these types of building energy improvement projects, some cities, including New York and Toronto, are not penalizing owners for exceeding limits on added floor area ratios that may result.
RIVERMARK/808 MEMORIAL DRIVE
Challenged to revive a grey-colored Brutalist residential complex in Cambridge, Mass., built back in 1972, Bruner/Cott Architects was searching for a cladding system to meet the project’s ambitious standards for energy efficiency, sustainability, recyclability, and durability. Informed by the results of a comprehensive analysis of the two building envelopes, it was determined that a facade overclad could be performed without major structural impacts or upgrades.
This was good news as new construction for a building this size would have been prohibitively expensive, not to mention the large quantity of carbon emissions that would have been required to rebuild the 10-story and 19-story buildings overlooking the Charles River. The recladding option also met Rivermark’s requirement that the 300 families living in the complex would not be displaced during the 30 months of construction.
To meet the above-mentioned performance goals, the architects ultimately chose clay and Sedona metal composite panels and insulated metal panels (IMP) for the 12-inch-thick cladding assembly system. The mix of two custom metallic colors creates a large diagonal stripe across the facades, replacing the worn concrete with colors matching Cambridge’s brick vernacular. Not only did the design inject new vibrancy and life into the tired-looking exterior, but the owner saw a significant jump in thermal performance and energy efficiencies.
Expounding upon the team’s decision to go with IMPs, Jason Jewhurst, FAIA, partner, principal, Bruner/Cott Architects, Brookline, Mass., explains that the cladding’s high thermal performance, excellent insulation, and air sealing properties helped reduce the building’s energy use intensity (EUI), carbon footprint and operating costs. “IMPs are durable, withstand the harsh weather that is common in New England, and are easy to maintain. They are made from a high percentage of recycled content and are fully recyclable, reducing landfill waste. Additionally, they are manufactured using a low-energy process, further reducing their environmental impact,” Jewhurst adds.
The cladding system design successfully combines two distinct systems into one air-sealed, thermally broken assembly. “A special aluminum extrusion was designed for panel joints, providing a continuous pathway for water and moisture weeping and compartmentalization for fire protection,” explains Jewhurst. “The visible portion of these joints were carefully reviewed for a smooth transition between prefabricated panel assemblies and to ensure a cohesive look on the building’s facade.”
Photos courtesy of Nucor Insulated Panel Group
Replacing the old concrete with colors matching Cambridge’s brick vernacular, Bruner/Cott specified metal composite panels and insulated metal panels to overclad 808 Memorial Drive in Cambridge, Mass. The IMPs significantly boosted energy performance and enabled the residents to stay in their homes throughout the retrofit.
FABRICATION AND INSTALLATION
To fabricate the panels, 70% of the work was performed in the shop, with the remaining 30% stick-built system using mast climbers. “We custom-designed all the horizontal IMP panels and CW frames to be mated together similar to a unitized curtainwall system. All the frames were built in shop and sent to site to be installed/hung using material hoists. System sleds/anchors were installed onto the building’s existing floor slabs and the overcladding was hung/installed similar to a unitized CW system,” explains Duc Vo, LEED Green Associate, senior project manager, curtainwall production coordinator, Sunrise Erectors, Canton, Mass.
In determining how to attach the panels to the wall, the existing conditions had to be carefully analyzed. “We discovered that the original ribbed faced concrete masonry units (CMU) block veneer infill needed to remain due to high removal and disposal costs. Removing the CMU infill would have exposed inside portions of the wall to the elements for long durations of time,” explains Jewhurst. Consequently, the IMP system is anchored to the precast concrete core floor planks, providing even support at each floor level.
In addition, common to architecture of the 1970s, it was discovered that some of the existing facades on both buildings were out of plumb by over five inches from top to bottom. To remedy this, the air cavity space and anchoring system had to be adjusted.
Vo explains that the project was infrared scanned and modeled in Revit. “We coordinated our shop drawings and superimposed the new overcladding onto the survey model, allowing us to coordinate material exactly to size. Once installed, industry-standard field control and survey were performed to confirm alignment,” he relates. “Even with the infrared model and field controls, the contractor hired surveyors to help us with the layout and alignment of the exterior overcladding.”
The panel fasteners were checked for the correct torque requirements per the manufacturer/engineering requirements, and pull testing was performed to ensure the anchors passed engineering requirements. In addition to the metal panels, existing window bays were replaced with new high-performance operable windows. The construction team first installed the new windows and then removed the old ones. Lastly, the assembly was sealed.
Through this process, constant communication and coordination were required to address resident needs while keeping the project on schedule and within budget. This involved careful planning with construction workers on-site, relocation team, movers, cleaners, and property management to minimize disturbances for the tenants.
The metal panels are finished with a polyvinylidene fluoride (PVDF) coating, meeting AAMA 2605 performance standards. The coil coating also ensures a high level of color consistency.
Other building updates included the replacement of central heating and domestic hot water systems with high-efficiency condensing boilers, efficient fan coil units in apartments, a new cogeneration plant providing efficient heating and low-cost electrical power to the site, new central ventilation, energy-efficient lighting, and low-flow bathroom fixtures. According to an audit performed by the Massachusetts Clean Energy Center, the remodeled buildings were projected to save 2,973,120 gallons of water, 141,659 kWh of electricity, 7,053 therms of natural gas, and $92,500 of annual utility savings.
Notice
