Insulated Metal Panels for Wall and Roofing Retrofits  

Photo courtesy of Kingspan Insulated Panels

Recladding with insulated metal panels is a great way to boost energy efficiencies and occupant comfort while delivering a refreshed, updated look as was done here for the decades-old 808 Memorial Drive apartment buildings in Cambridge, Mass.

Checking all the boxes for high performance, sustainability, longevity, aesthetics, and affordability, insulated metal panels for wall and roofing systems are an increasingly popular option for a wide range of projects from healthcare to schools to offices to recreation to retail to multifamily, and the list goes on. Delivering air, water, and moisture protection, together with unmatchable thermal performance, Insulated Metal Panels (“IMPs”) are a fantastic “one and done” option for building enclosures. The versatile panels are also gaining traction in the growing retrofit market as building teams look to refresh and update their cladding and roofing systems with tighter, better-performing enclosures.

“Insulated metal panel retrofits for roofing and walls offer both the practicality of a lightweight, continuously-insulated skin and the design incentive of clean lines, durable finishes, and integrated detailing,” states Colin Drake, FAIA, LEED AP, principal, JRA Architects, Louisville, Ky. Bruner/Cott Architects also chooses IMP cladding and roofing systems for many of their retrofit projects on account of the product’s versatility, ability to meet and exceed energy code requirements, and its adaptability for historical renovation projects.

Presently, the market for IMPs is approximately five times larger in Europe than in North America. But as more projects are installed and the building market learns more about the technology, U.S., and Canadian projects are anticipated to grow. Before delving into IMPs compatibility with retrofit projects, it’s important to appreciate the extent to which the market has evolved in recent years.

RETROFIT BOOM

While an increased focus on building retrofits traditionally occurs during economic slowdowns when there isn’t as much capital to fund new development, something changed a few years ago. In a recent American Institute of Architects report entitled “Renovate, Retrofit, Reuse: Uncovering the Hidden Value in America’s Existing Building Stock,”¹ the authors explain that following the Great Recession in 2008- 2009, retrofit projects increased significantly and have remained a strong percentage of all construction projects ever since then. In fact, in the spring of 2022, retrofit work surpassed 50% of the market for the first time, overshadowing new construction. “New highs in boom-time renovation work represent a shifting trend with significant implications for the profession and for the environment,” states the paper. “Even as the economy has recovered from the Great Recession-and the construction sector has surged in recent years–the proportion of architects’ work on existing buildings has held steady.” “The most logical thing we can do to decrease our impact on the planet is to reuse what already exists,” stated Jean Carroon, FAIA, Goody Clancy. Really driving this point home, Carl Elefante, former president of the American Institute of Architects is famously quoted as saying, “The greenest building is the one that already exists.”

Photo courtesy of Nucor Insulated Panel Group

A former factory-turned-school, Essex County West Caldwell School in West Caldwell, N.J., recently received another facelift with IMP wall panels to boost thermal performance and help convey to help convey the high-tech, modern look the school was after.

As interest in issues like health and well-being, social impacts, biodiversity, and climate resilience rise in importance, particularly in more architecturally progressive markets like California, New York, and Boston, owners and architects are taking a more serious look at building retrofits and renovations and reroofing and recladding. As stated in a “Retrofit Revolution” report² by the UBS Sustainability and Impact Institute, “the existing building stock is mostly energy inefficient, and adversely impacts the health and comfort of inhabitants, leading to costly medical, social, and economic outcomes. Retrofitted buildings that are better insulated, better ventilated, and smarter reduce emissions and the strain on grids as the economy electrifies while improving health outcomes,” while buildings age and older facade systems are no longer delivering acceptable levels of energy efficiency and occupant comfort, not to mention aesthetics. Instead, the building codes and the marketplace are demanding more. For example, Class B and Class C office buildings are finding it difficult to fill occupancies, particularly if the building is drafty and tired-looking with high energy bills. This summer, Moody Analytics reported that office vacancies had hit an all-time high of 20.1%, breaking the 20% barrier for the first time in history. In all, a whopping 1 billion square feet of office space in the U.S. is sitting vacant.

While upgrading the building enclosure is not a low-cost nor low-hanging fruit approach to increasing a building’s value in the short term, it is a very viable longer-term investment, which shouldn’t be overlooked. Further more, destroying and replacing the building is certainly higher cost than retrofitting an existing building. A new facade upgrade is not going to deliver that quick ROI. However, such an investment will optimally position the property towards where the market is headed. “Take a building that today is worth $100 million and requires a $15-million upgrade. That may never pencil out on an operating-cost break-even basis. But as tenant demand for low-carbon buildings accelerates, there’s a risk that the building’s value falls because it’s unable to meet the tenants’ low-carbon targets, which in turn affects the number of potential future buyers. On the other hand, low-carbon space can earn a substantial premium from retrofit investments,” states Greg Bolino, Head of Global Sustainability Strategy & Assets, JLL. In the shorter term, rising energy costs, market pressure to meet sustainable building certifications, and developing codes and standards are making reclads and roofing retrofits more viable.

Photos courtesy of Kingspan Insulated Panels

IMP’s insulation capabilities and speed to erection helped drive Holly and Smith Architect’s selection of the colorful wall panels for Mandeville High School in Mandeville, La.

 

 

UNDERSTANDING IMPS

Before delving into some details and best practices for recladding and reroofing buildings with IMP systems, a general overview of the technology and its benefits is in order. IMPs are made from two sheets of metal sandwiched with rigid insulative foam core. In addition to servicing as an all-in-one air, water, and vapor barrier­­-fully tested for structural, thermal, and fire protection performance-IMPs deliver exceptionally high thermal performance with complete insulation. In fact, at R7 to R8 per inch, IMPs are one of the greatest pound-for-pound materials in the marketplace when it comes to thermal value per inch. As a point of comparison, the R Value per inch of other types of common insulation materials is R5 for extruded polystyrene, R4 for expanded polystyrene, and R3 for mineral fiber and cellular glass. Virtually eliminating thermal bridging, the system serves as a full thermal barrier, which is becoming a code requirement in many municipalities. Highlighting the significance and importance of thermal performance, the Building Science Corporation (BSC)³ performed a study comparing IMPs to other enclosure systems. The building scientists point out that typical roofing installations are challenged with thermal conductivity through the steel framing/studs and air leakage through and around improperly installed internal frames or cavity insulation. These issues combined can reduce the effective thermal resistance of the assembly by over 50%. Consequently, a fully insulated wall is the best way to avoid this.

In comparing IMPs to blanket insulation purlin roof systems, these systems are challenged with thermal conductivity issues and therefore do not provide comparable performance to IMP roof assemblies. For non-insulated, i.e., concrete tilt-up and insulated mass wall assemblies, BSC says they are problematic in hot humid climates and mixed humid climates as the latent load of the outdoor air introduced by the humidity makes it difficult to use ventilation air for energy removal at night. In addition, they are problematic in cold climates because the interior surface of the mass wall stays below the comfort level as there is insufficient thermal energy available from the exterior. “Insulated metal panel systems provide all the required functions needed from a proper building enclosure with less materials needed to install and provide a better performing, energy-efficient building,” states the study.

While these insulating values gave IMPs their start in cold storage, manufacturing, and processing facilities which required climate-controlled environments, the products’ durability, light weight, and appealing aesthetics have significantly expanded their reach to healthcare, education, recreation, transportation, offices, and hospitality facilities. The panels integrate well with customized windows, louvers, and sunshade systems, and like other metal roof systems, they serve as a great platform for solar photovoltaics. And because they are pre-assembled as a fully integrated building envelope system with a high level of quality control, this better ensures performance and uniformity in appearance.

IMP wall and roof panels come in a wide range of custom shapes, print patterns, colors, and finishes. Architects can tap into the creative possibilities of forming dynamic curves, geometric patterns, and everything in between. Panels can be smooth or textured in a variety of expressions including striated, fluted, grooved, or embossed. This flexibility enables designers to fit their facade and roofing designs within the context of the surrounding architecture and style. “I have seen quite a bit of design flexibility with these systems,” observes Alexander Zilberman, AIA, AZA-Alexander Zilberman Architecture, New York City. “You can have a standing seam profile, modularize it and you have the benefit of a factory finish-either off the shelf or a custom finish, including anodized finishes.”

Zilberman also likes IMPs' bespoke capabilities and their ability to integrate with an array of products like fascias, rakes, soffits, and gutter systems. But the fact that IMPs incorporate air, water, vapor protection, and thermal performance within one system is key. “As a designer, it frees me because it’s unnecessary to detail all those components or figure out how it works with other manufacturers’ products. So you are picking things off of a menu, in this way,” he says.

Eliminating the need to interface with multiple components and manufacturers for the building enclosure design and installation, boosts performance, prevents installation errors, simplifies the design, and expedites design, procurement, and installation. The pre-assembled IMPs arrive on-site ready for installation. The lightweight of the panels makes them easier to install. And as full thermal, water, air, and vapor-tight enclosure, the sequencing of construction and permits can be fast-tracked. This not only minimizes the risk of adverse weather slowing down construction but also enables project teams to get started on the interior work much quicker. Depending on job complexity and size, IMPs can be erected at a rate of up to 5,000 square feet per eight-hour shift by a four-man crew on an industrial project and up to 1,100 square feet during an eight-hour shift by a four-man crew on an architectural project when proper lifting equipment is used. Case in point, Zilberman recently specified IMPs, together with composite aluminum panels for the roof of a large retail complex in New York. As the most efficient and effective roofing system to install, the panels added significant insulation and energy efficiencies. and enabled the mall to meet all its design and building code requirements.

While lighter-weight roofing systems are of benefit in many applications, this advantage is particularly poignant with aging structures and in seismic zones. The lighter-weight panels can be installed in larger spans. As compared to conventional cladding, which requires screws every few inches to secure the panels to the structure, IMPs reduction in anchor points significantly minimizes the risk of air and water infiltration, and thermal bridging.

On the topic of sustainability, the metal facings are 100% recyclable and incorporate a minimum of 30% recycled content. The insulating cores meet current U.S. Environmental Protection Agency requirements for global warming potential reduction, VOC content, and have zero ozone-depleting potential.

As for longevity, an oft-quoted study performed by the Metal Construction Association and ZAC Association,⁴ with oversight from three independent consulting firms, found that a low-slope, unpainted 55% Al-Zn coated steel standing seam roofing system can last as long as 60 years. And like all metal shingles, IMPs undergo aggressive structural performance testing. Structurally, IMP roof panels offer a high strength-to-weight ratio. In addition to their strength and insulating properties, the panels are highly weather- and corrosion-resistant, making them appealing for cold climates and coastal regions.

Photo courtesy of Kingspan Insulated Panels

At the Gusto 501 restaurant in Toronto, insulated metal panels in varying shapes and cascading designs were selected for their aesthetics, cost savings, and speed to construction.

Photo courtesy of of Wood's Powr Group Co.

IMPs can be erected at a rate of up to 5,000 square feet per eight-hour shift by a four-man crew on an industrial project.

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.

INFLATION REDUCTION ACT

Even more significant, the U.S. Inflation Reduction Act (IRA) of 2022 is offering significant incentives to help drive energy-efficient improvements in projects. The IRA modifies the tax incentive under section 179D of the Internal Revenue Code for energy-efficient improvements to existing commercial buildings, in addition to new construction, with increased deduction limits and other changes. In lieu of a one-time $1.88 per square foot tax reduction cap under the previous program, building owners can qualify for a reduction of up to $5 per square foot and can apply for the credit every three years.

To qualify, the improvement measures must enable the facility to use 25% less energy than a comparable building. With a 25% reduction, this means that the upgrade will yield a 50 cent per square foot deduction, scaling up to a $1 per square foot deduction for a 50% efficiency gain. The deduction then increases on a sliding scale by $0.10 for each additional 1% improvement up to a maximum of $5 per square foot.

Energy savings, measured as an EUI reduction, are based on a measurement of the building’s actual energy use over the course of 12 months before and after the energy upgrade. Applying this opportunity to roofing upgrades, ICF International released a study in 2021 entitled “Life-Cycle Benefits of Energy Code-Compliant Roof Replacement.”²⁶ The study found that upgrading a typical existing low-slope roof to a code-compliant roof can result in significant whole-building energy savings.

Further, a roof improvement project could increase the 179D deduction in a range of $0.20 to $1.10 per square foot depending on the building type and climate zone, with an average increase would be $0.60 per square foot. In colder climates, and for building types with large roof-to-floor ratios like schools and large retail, savings will be even greater. Consequently, roofing upgrades are highly recommended for owners and architects looking to cash in on IRA tax reduction benefits.

Photo courtesy of Nucor Insulated Panel Group

After a fire damaged the Wurstfest festival venue in Braunfels, Texas, the event organizers were in a hurry to rebuild in time for the annual festival. IMPs were chosen for their speed to construction and enhanced structural performance.

RETROFITTING WITH IMPS

In addition to the many noted benefits IMPs for new construction, the panels are a great choice for building enclosure upgrades. “IMP assemblies are increasingly popular for deep energy retrofits, additions, and recladding projects, especially in the northeast climate zone,” states Jason Jewhurst, FAIA, partner and principal, Bruner/Cott Architects, Brookline, Mass.

IMPs can be installed over many types of backup walls including wood, steel, concrete, and masonry. And the system’s ease of installation reduces costs schedules and labor costs. As noted, IMPs are fire resistant, and overcladding boosts acoustic performance as well.

In addition to presenting a fresh, updated facade, perhaps the biggest benefit is the boost in thermal savings. And thanks to IMP’s all-in-one water, vapor, and air barrier, those performance savings are locked in. Also of note, the IMP's air and water seal is located on the interior side of the panel and in the panel joinery. This design allows it to be completely concealed and not visible to the exterior.

“Leveraging high performance, time-tested materials like IMPs for building retrofit is just a natural extension of the same value these materials have proven over decades of successful application,” states Drake. “Few alternatives offer such lightweight, long-span, single-source applicability as IMPs, and their long history with integrated glazing, flashing, and design options further offer solutions that can increase the aesthetic results while extending buildings’ productive lifespans.” For IMP roofing retrofits in particular, while the new roof is highly thermally efficient, re-roofs can also capitalize on the roof’s existing insulation.

As noted, the building stays dry and weather-resistant during installation, and workers are afforded an existing work surface as opposed to the open purlins and joists with new roof construction. In addition, the through-fastened metal roof system diaphragm remains in place thereby preserving the original structural diaphragm strength used to design the original structure.

When re-roofing with an IMP, as opposed to completely removing the existing roof structure, building teams have the option of preserving the structure by adding a sub-framing system. These sub-purlins are structural members, typically 10 to 12 feet in length, made from 16 gauge, 0.060-inch-minimum 50 KSI structural grade G-90 galvanized steel and notched to fit over the ribs of the existing metal roof panels.

Factory notching provides a “structure to structure” connection with the least possible increase in assembly height. The system also adds strength to the existing roof system thereby offsetting the added weight of the new metal-over-metal roof components. These sub-purlins can be fabricated for almost any existing metal roof panel profile including screw-down, standing seams, and custom heights to accommodate added insulation between the old and new roofs. Some products offer an “anti-rotational” arm to stabilize the framing system that is attached over compressible insulation materials.

54 MIDDLESEX

Bringing a worn-out-looking 1970s office building back to life in Bedford, Mass., Bruner/Cott Architects designed a hybrid assembly of insulated metal panels (IMP) and high-performance ribbon curtainwall windows. Similar to existing buildings of this vintage, the project’s design capacities required that the recladding be heavier than the original veneer brick facade. However, a new masonry façade would have cost twice as much as metal. “The combination of high thermal performance per square foot of façade, low weight per square foot, competitive cost of fabrication, and installation made IMPs a strong candidate for a project of this scale and budget,” reports Jason Jewhurst, FAIA, Partner, Principal, Bruner/Cott Architects, Brookline, Mass. “Insulated metal panels allowed us to pull it all together and provide the updated aesthetic the owner was seeking in an energy-saving system,” added Michael Frechette, AIA, then a project architect with the project’s contractor Dacon Corporation.

Photos courtesy of Nucor Insulated Panel Group

 

 

 

 

 

In all, 16,000 square feet of grey and white 3-inch IMPs, in 24-inch and 36-inch widths, were installed. The selected panels have a 22-gauge exterior skin and a 26-gauge interior skin. The horizontal IMPs were installed in widths consistent with windows and other design elements of the building.“It’s a lot more difficult to do a horizontal renovation than a new vertical installation,” related Dave McGrath, a sales engineer with the Mansfield, Mass.-based Controlled Environment Structures (CES), whose firm installed the facade, “We had to line up our seams with the mullions on the storefront windows. There is a lot of custom fieldwork because we weren’t working off a blueprint; these are field conditions.” For example, the original concrete masonry unit presented a very rough surface, and the aesthetic was not desired for the new facade. To rectify this, CES came up with a clever solution to attach the IMPs to a sub-framing system, fully concealing the CMUs.

In addition, a continuous bracing clip had to be installed prior to the panel installation to provide lateral bracing. “The bays of the building are 28 feet across and required intermittent lateral bracing between the structural columns,” explains Frechette. “The system was fabricated such that it could be lifted into place by a crane and mechanically anchored from inside the building, making it very easy for workers to safely and efficiently install the panels once arrived at the site.“ He adds that the system had to be detailed to accommodate imperfections in the existing cast-in-place structure. This informed how the panel joints and expansion joints would allow for a degree of adjustability during the site installation.

Another challenge was working with panels and their smooth finish. Because any imperfection is exposed, the quality of manufacturing with the IMPs had to be right on. Fortunately, it was. “The smooth finish adds to the crisp geometry the owner wanted,” Frechette says. “It is a clean aesthetic and an upgrade from the typical embossed finish.” Ultimately, the project team was amazed at the level of thermal efficiency that the IMPs deliver.

“The energy efficiency of the metal panels is a decrease of two-thirds the amount lost through the walls and the savings is something like 70 cents a square foot over 40,000 square feet, reports Dacon Senior Project Manager Jeff Prince. “We had heard that it was going to be beneficial, but it really wasn’t until the tangible savings that we saw on our energy costs for managing and maintaining the building that it really became apparent,” echoed Ian Curran, Director of Leasing, Curran Management, the building owner.

INSTALLATION STRATEGIES

While the embodied carbon, labor, and cost savings associated with IMP recladding and reroofing while using the existing structural system are significant, the process of aligning and attaching the new panels to the substrate can be challenging. Whereas “ground-up IMP projects get to make the rules and dimensional tolerances that best suit the new building, overcladding projects require the team to respond to the dimensional parameters set by the existing structure and then form a framework and dimensional guidelines that respond and intersect with the existing topography of the vertical surfaces or facade of the existing building,” explains Jewhurst. Furthermore, building teams must contend with a certain level of unpredictability regarding the state of the existing substructure and the substrate to which the new panels are being attached. If the structure is flawed or degraded, this can impact the quality of the installation and the IMP warranty.

To help mitigate this risk, Drake recommends inspecting the substrate, and, if possible, probing the structure. It is also best practice to confirm that the receiving structures and surfaces meet the manufacturers’ requirements. “Structural design must be front and center when applying a new skin over an existing envelope. Whereas a new building can count on a fully code-compliant assembly, and typical material attachment, over-cladding demands attention early on to be sure that the new, high-performance skin has adequate support,” he states. This involves reviewing the specifics of the detailing with the IMP manufacturer and structural engineer to best ensure compatibility, as noted.

Vo agrees that structural support for the new cladding system is the most important item to design and engineer from the onset of a project. One strategy he suggests is leaning into the unitization and prefabrication capabilities of IMP systems. To optimally execute this, it’s important to establish sizes and spans for unitization that will meet engineering requirements and existing building parameters.

Another best practice, says Drake, is vetting the right IMP product for the job. “It’s even better to confirm integration with numerous reputable manufacturers to assure competitive bidding and the best system for the project’s unique challenges” he explains. “These are very efficient panel modules, but only when they arrive on site prepped for a project’s specific parameters.”

Important details include flashings at transitions, penetrations, curbs, terminations, and panel end lap. “Detailing is everything for wall retrofit success,” emphasizes Drake. “Flashing conditions at openings, coordination at the top and bottom of panel transitions, and effective planning for unique penetrations are no less critical than any other assembly. Attention to detail for air and water management, as well as care for the inevitable, atypical moments on a building, set a project up for success.”

Photos courtesy of All Weather Insulated Panels

Using vacuum suctioning, IMP roof, and wall panels for Wood's Powr-Grip’s manufacturing facility were installed in just two weeks.

 

 

ROOFING PROFILES AND INSTALLATION

For IMP standing seam roofing systems, both retrofits and new construction, the product offers the advantage of ease and speed of installation. As opposed to multi-piece field-assembled metal systems or built-up roof systems, which require several individual layers and components, an IMP installation includes one step because all the components are contained within the panel. This simplified installation process delivers labor savings and shorter project schedules. In addition, interior work can then begin sooner.

IMP roof panels come in two profiles: standing seam and through-fastened. The standing seam profile roof panels are typically mechanically seamed together during installation with no exposed fasteners within the envelope boundaries. The fasteners that connect the panel to the roof framing are covered when the next panel is joined to it. A traditional joinery is a standing seam panel with a 2-inch straight leg, and some manufacturers offer panels with a T-shaped joinery and or trapezoidal joinery The latter option has a 2-inch leg and a trapezoidal lower half, creating a panel installation with greater dimension across the face of the roof. Through-fastened profiles have exposed fasteners. Though not as aesthetic, they offer the advantage of faster installation because they do not require that the installer mechanically seam the panels together.

A noted benefit of IMP systems is the nature of the sandwiched panels means there is no significant linear differential expansion between the interior and exterior facings. Instead, the expansion of the panel is distributed among the individual spans as curvature, which is called thermal bow. Because the overall panel does not significantly elongate or contract, there is no need to install an IMP roof panel with slotted clips.

IMP roofing installs also require the creation of an end lap on the panel at the perimeter of the roof to be able to perfectly fit the panel onto the roof. To create an end lap, installers typically cut away the inner-facing liner and foam core, leaving a small exterior-facing extension that will then lap over the lower panel. The length of the extension and end lap is dependent on the slope of the roof and panel profile. The end lap joints are caulked and fastened according to the roof panel manufacturer’s recommendations. The tool for cutting should be designed to cut metal panels. Reciprocating saws are not recommended.

When lifting the panels, a common method is wall clamps. At least 12 gauge is recommended. Though more common in Europe, vacuum or section lifting can be a very safe, efficient method.

CONCLUSION

In sum, a number of variables are driving interest in retrofitting older buildings and, particularly, recladding, and reroofing projects. Growing concerns about energy efficiency, sustainable design, the use of resources, operating expenses, energy use, labor, and incentives are all encouraging building owners to consider renovation over new construction.

Generally speaking, as reported in Metal Architecture magazine, metal roof shipments are expected to grow 5% this year, the metal wall market is expected to be approximately $2.8 billion by 2025, and IMP adoption is contributing to this growth. Essentially, industry experts anticipate that North American IMP applications will begin catching up with popularity in Europe. “Predicted growth in the industries that are well suited for IMPs will result in commensurate growth in the use of IMPs,” agrees recently retired industry consultant Brian Gardiner, FRCI, RRC, CCS.

Meanwhile, experts anticipate IMP roofing and wall renovations will play a significant role. “We anticipate IMP retrofits will become more prevalent in the coming years, especially with 70s Brutalist architecture and the updated energy requirements. If planned properly and thoughtfully, overcladding will have less impact on the occupants and property overall,” states Vo. In conclusion, Zilberman predicts, “Expect more bespoke projects. As manufacturers are being challenged by project-specific scenarios, there will be more and more opportunities for custom, design-specific applications. These will help design teams achieve both performance and aesthetic for all projects.”

END NOTES

¹American Institute of Architects, “Renovate, Retrofit, Reuse,” 29, Nov. 2023. .
²UBS Sustainability and Impact Institute. “Retrofit Revolution,” Nov. 2023. < https://www.ubs.com/global/en/sustainability-impact/sustainability-insights/reports/retrofit-revolution.html>
³“Building Science Corporation Digest of Insulated Metal Panels,” Nov. 2022. < https://www.metlspan.com/wp-content/uploads/2022/11/MIMP-251-White-Paper-Update-FINAL-WEB.pdf?_gl=1*18be2fp*_ga*MTcwOTY2NTA0Ni4xNjkwMzc5MDQ5*_ga_HPMHMWTESP*MTY5OTk3MTY4Ny4yNDkuMS4xNjk5OTc0NjY4LjU0LjAuMA..>.
⁴“Service Life Assessment of Low-Slope Metal Roof Systems,” Nov. 2014., https://www.metalconstruction.org/index.php/online-education/service-life-assessment-of-low-slope-unpainted-55-al-zn-alloy-coated-steel-standing-seam-metal-roof-systems---published-102018>.
⁵Aronov, Albert. “Overcladding for Od Masonry Facades: Why it is Important to Think Performance First,” Nov. 3, 2021. < https://www.constructionspecifier.com/overcladding-for-old-masonry-facades-why-it-is-important-to-think-performance-first/>
⁶ICF International. “Life-Cycle Benefits of Energy Code-Compliant Roof Replacement,” Oct. 1. 2021. < https://cdn.ymaws.com/www.polyiso.org/resource/resmgr/ifcreports/PIMA_Life_Cycle_Cost_Analysi.pdf>.

Barbara Horwitz-Bennett is a veteran architectural journalist who has written hundreds of CEUs and articles for various AEC publications.www.linkedin.com/in/barbarahbennett