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Metal Wall Panels on the Roof: How to achieve durability and reliability using sheet metal

All images courtesy Simpson Gumpertz & Heger

All images courtesy Simpson Gumpertz & Heger

by Scott A. Tomlinson, PE, and Matthew M. Copeland, PE

Sheet metal has been used as a roofing material for centuries on all types of structures. Copper, stainless and galvanized steel, aluminum, and zinc are commonly employed in various low- and steep-slope assemblies. Designers and contractors know from centuries of accumulated knowledge how to achieve durable and reliable roofing assemblies using these types of sheet metal. But what about newer materials?

Modern architectural designs often use newer materials and metal panel assemblies for roofing applications, some of which are not intended to be used as roofing and, therefore, may not be well-suited for it. One such trend is the use of architectural metal wall panels (e.g. metal composite material [MCM]) as roofing to create a visually seamless transition between building walls and roof surfaces, such as low-slope setbacks in the façade. Whether in low- or steep-slope assemblies, using metal wall panels in roof applications presents unique challenges for the designer and contractor.

This article focuses on use of architectural metal wall panels in low-slope ‘brow’ roofing (Figure 1). It also includes a brief discussion of contractor coordination essential to success, particularly since metal wall panel contractors typically have a different set of skills and training than roofing contractors. The installation of metal wall panels on larger low-slope roof areas includes additional complications and risks not discussed in this article.

Generally, architectural metal wall panels are not well-suited for roofing applications. Even in vertical applications, these systems are not typically intended to be watertight. The systems incorporate water management strategies and a water-resistive barrier (WRB) behind the panels (i.e. a rainscreen) to accommodate water that penetrates the panels. It is unreasonable to expect these same panel systems and water-resistive barriers to be watertight when installed nearly horizontal and skyward-facing.

Therefore, the panels must be considered a water-shedding layer, much like roofing shingles, and roofing underlayment is required to accommodate water that penetrates the panel system. The underlayment must be designed and constructed to perform as ‘waterproofing.’ Self-adhering membrane roofing underlayment (referred to as a ‘membrane’ in this article) is well-suited for this application.

Panel skyward-facing surface water management
The panels should be considered the water-shedding layer and the roofing underlayment the primary waterproofing. That said, the panels should be designed and installed to shed as much water as practical to drainage locations and minimize water penetration to the waterproofing membrane. Allowing an excessive volume of water to penetrate the panel system to the membrane increases the risk of leakage through panel attachments, vulnerable details, and construction imperfections in the membrane system. Providing the maximum slope permitted by the design generally directs water away from vulnerable flashings and joints, and decreases water penetration through the panel system.CS_September_2014.indd

Providing a gutter system underneath skyward-facing panel joints (e.g. using splines in panel joints to create a gutter) and sealing the joints (e.g. sealant and backer rod if aesthetically acceptable) minimizes water penetration to the membrane (Figure 2); gutters should be used when possible. Depending on the roof geometry, some assemblies may not accommodate gutters underneath the joints because there is no place to drain water in the gutters; sealant should still be installed in these joints and should be maintained over time as the joints deteriorate. Returns at panel joints should be used to form gutters and receive sealant.

Panel internal vs. eave edge drainage
Sloping the panels to drain over edges is preferred to internally draining the roof. Systems that drain over edges more readily accommodate steep slopes, and minimize water penetration to the membrane (i.e. water does not have to flow to a drain in the membrane). Further, sloping of the panel planes and valleys is simpler because they do not need to conduct water to drain holes. Properly designed snow guards can mitigate the risk of falling snow and ice in colder climates.

Where draining to the exterior wall is unacceptable, the design must incorporate internal drainage or a perimeter gutter. Roof drains must provide drainage at both panel and membrane levels. One option is to provide a drain at the membrane level and holes in the panels directly over the drains (covered with perforated metal—additional ultraviolet [UV] protection of the membrane below may be required). Bi-level drains can also be used. The drains must be installed at the low points in the roof system. Slope and valleys in the panel system must direct water to the drain holes. Designers should consider heat tracing the drains where water can freeze and impede drainage (i.e. at canopy conditions where the drains do not enter heated space).

When a perimeter gutter system is used, the membrane and panels must integrate with the gutters. However, this detailing has intricacies beyond this article’s scope.

Panel impact on membrane level drainage
Unimpeded water drainage is critical at both the panel and membrane surfaces. The risk of water leakage through the self-adhering membrane (e.g. through weak seams, holes, and other imperfections) rises as the water’s volume, depth, and dwell time on the membrane increases.

Panel edges returned to form joints and gutters, and to receive sealant joints, should not extend all the way to the membrane surface. There should be a gap provided between the bottom edge of the return and self-adhering membrane to allow for drainage and reduce the risk of damage to the self-adhering membrane. The gap should be as large as practical (e.g. 25 mm [1 in.]), but not less than 6 mm (1/4 in.).

Panel attachment
The panels must be anchored to the roof structure to meet wind uplift and other loading requirements while maintaining the self-adhering membrane’s waterproofing integrity. Panel attachment clips are typically fastened with screws through the membrane to the structural sheathing or framing underneath the sheathing.

Panel attachment clips should be designed and positioned so they do not impede membrane level drainage. Using discrete clips (e.g. 100-mm [4-in.] long) in lieu of longer or continuous ones reduces the risk of impeding drainage. It is also important to install clips as far as practical away from drains and designed drainage paths such as valleys. This reduces the risk of impeding drainage and water leakage through the fastener penetrations, which are the weak point in the membrane system.

The clips should be fastened with wood screws to increase the likelihood of the membrane self-sealing to the fastener. The drilling action of self-drilling screws can damage the membrane and reduce the self-sealability.

Installing the clips on multiple pieces of membrane squares (e.g. 100-mm [4-in.] square, as shown in Figure 2) each, adhered to the layer below, increases the membrane thickness and self-sealability, and raises the elevation of the fastener penetrations above the membrane surface on which water flows. Setting the attachment clips in mastic atop the squares, before fastening, further increases the self-sealability of the fastener penetration.

A more reliable solution to attaching the panels with clips directly through the membrane waterproofing is to construct stanchions to which the panels are mounted. Stanchions provide penetrations that can be reliably waterproofed, but is a more custom assembly that increases the roof assembly’s overall thickness and cost.

Waterproofing materials
The waterproofing membrane is the critical component in a roof assembly using metal wall panels, and a self-adhering membrane is well suited for this application. Like most products, not all self-adhering membranes are equal. Some membranes form more reliable laps, adhere better, seal better around fasteners, are easier to handle and install, or can tolerate higher service temperatures.CS_September_2014.indd

Additionally, some membrane manufacturers have more ancillary products, technical support, and a longer track record of success. The designer must determine the appropriate membrane products, with the understanding it will be used as waterproofing.

Use self-adhering membrane designed for use as a roofing underlayment.
The membrane should meet ASTM D1970, Standard Specification for Self-adhering Polymer Modified Bituminous Sheet Materials Used as Steep Roofing Underlayment for Ice Dam Protection; the requirements for self-sealability and lap integrity under a head of water are particularly important. More flexible membranes are typically better for detailing, but can be more difficult to install.

The designer should consider specifying flood testing of the installed membrane. Also, it is important to note these products function as vapor retarders—therefore, the system as a whole must be evaluated for condensation resistance.

Specify rubberized asphalt-based adhesive instead of butyl-based adhesive where service temperature and compatibility permits.
It is the authors’ experience rubberized asphalt adhesive achieves higher initial and long-term adhesion. Substrates should be primed to improve membrane bond, even when not required by the membrane manufacturer.

Specify mastic and fluid-applied membrane at seams and details.
The membrane must be installed watertight on its own, but mastic installed over the membrane at seams and details can provide an additional layer of protection. Fluid-applied membrane can be installed underneath the membrane to form smooth transitions (e.g. cants) at inside corner details and to make three-dimensional details watertight.

Waterproofing installation
The self-adhering membrane must be properly installed to perform as waterproofing. The membrane system (and panel system flashing) must turn up building walls and integrate with flashings and the air/water/vapor barrier on the walls. The membrane must be uninterrupted by metal flashings so it is fully waterproof.

Slope
The membrane must be sloped to the drains (internally drained) or eave edges (edge drained). For an edge-drained system, the design must incorporate a gap at the eave edges to allow water on the membrane to drain out of the roofing assembly. The 2012 International Building Code (IBC) requires a minimum of 1/4 in. per ft for roofs—more slope is generally better. This minimum slope must be provided at the membrane level, which serves as the primary waterproofing (Figure 3), but should also be provided at the skyward-facing panel surface to help reduce water infiltration down to the membrane.

Substrate preparation
The substrate must be properly supported and attached and have smooth transitions at joints to prevent damage to the membrane during service. Uneven transitions and gaps should be bridged with sheet metal well-fastened to limit thermal movement that can cut the membrane. A fluid-applied cant improves seam reliability by easing the membrane transition and allowing the installer to apply the required pressure to form a reliable seal at seams. CS_September_2014.indd

Proper adhesion and reliable seams
Self-adhering membrane must be ‘fully’ supported and adhered to provide effective waterproofing and reliable seams. The substrate must be clean and dry, and the membrane must be firmly ‘pressed’ onto the substrate; hard rollers can help.

The pieces of membrane must be ‘fully’ adhered to each other at seams with no pathways for water (e.g. wrinkles).

Serviceability
Roof drains require maintenance. The hole in the panels at drains must be covered with a perforated material; this cover must be removable to allow maintenance workers to access and maintain the drain.

Metal wall panels are not designed to accommodate live loads imposed by maintenance workers in a horizontal application. If sealant joints and drains cannot be serviced without walking or kneeling on the panels, the designer should consider methods of providing supplemental panel support and/or maintenance worker load distribution.

The authors have considered using moisture-tolerant high-load capacity rigid insulation over drainage mat between the top of the self-adhering membrane and the underside of the panels (fit snugly) to provide additional support. However, such a system has yet to be installed or tested.

Contractor co-ordination
Critical to the successful performance of a metal wall panel low-slope roof is both the designer and contractor believing the panels must minimize water penetration to the membrane, and the membrane must perform as ‘waterproofing.’

A pre-construction meeting is beneficial to clarify design intent and project requirements. The pre-construction meeting should include the:

  • designer;
  • general contractor;
  • metal panel subcontractor;
  • subcontractor responsible for installing the membrane; and
  • other involved contractors.

The meeting should include discussion of the following:

  1. The designer and contractor must understand the panels are a first line of defense intended to shed water and minimize the volume of water that reaches the membrane. The panels themselves are impermeable, but the joints and flashing, even if protected with gutters and sealants, will permit water penetration through the panel system. Water penetration will increase as sealants deteriorate.
  2. The construction schedule should allow adequate time for inspection of the membrane installation before installation of any overlying materials, including any mastics/sealants applied over seams in the membrane (i.e. membrane must be inspected prior to applying mastics/sealants). The membrane installation must be watertight on its own; flood testing requirements need to be coordinated with the project team at the pre-construction meeting. The designer and contractor should expect that water will pond on the membrane under certain conditions.
  3. Panel shop drawings must be coordinated with the roofing design and installation so water drainage is directed to the appropriate location. For example, panel valleys should conduct water directly to the drains, not simply to their general vicinity. Shop drawings should indicate location and size of metal panel anchors as well as joints between panels. Perimeter flashing and other transitions to adjacent construction should be coordinated on the shop drawings, with clear indication of responsibility. Adequate coordination may require additional effort on behalf of the general contractor.

Conclusion
Architectural metal wall panels can be used with success in a low-slope roofing application with proper design and construction. Success requires the designer, contractor, and end user to understand the panels are a first line of defense intended to shed as much water as practical, while the self-adhering membrane level must be designed and installed as waterproofing. Additionally, the system must be maintained. Sealant joints require regular inspection and replacement, and drains demand cleaning.

Before designing and constructing a roofing system using architectural metal wall panels, the owner and designer must be aware of the risks. These include leakage, warranty implications (i.e. will leakage be covered by a long-term warranty?), and cost of repair. In some instances, the risks may be more than the designer and/or owner can tolerate.

Scott A. Tomlinson, PE, is a senior project manager at Simpson Gumpertz & Heger Inc. (SGH), with more than 15 years of experience designing, constructing, investigating, and repairing building-envelope systems of all types. He can be reached at satomlinson@sgh.com.

Matthew M. Copeland, PE, is a senior staff I at SGH, with more than eight years of experience. He specializes in the design, investigation, and rehabilitation of building envelope systems for both historic and contemporary structures, with a focus on materials science issues. Copeland can be contacted via e-mail at mmcopeland@sgh.com.

 

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Solar Air-heating Systems 101: Cigas Machine Shop

A total of 1084 m2 (11,670 sf) of black, transpired solar collector wall panels were installed at the Cigas Machine Shop in Pottstown, Pennsylvania. Photo courtesy ATAS International

A total of 1084 m2 (11,670 sf) of black, transpired solar collector wall panels were installed at the Cigas Machine Shop in Pottstown, Pennsylvania. Photo courtesy ATAS International

The Cigas Machine Shop in Pottstown, Pennsylvania, is located in a building previously owned by the Bethlehem Steel Corporation, with parts of the structure dating back to the late 1880s. Back in that era, Bethlehem Steel was involved in the production of fabricated components used in the construction of the Golden Gate and many other familiar bridges.

When Cigas took possession of the building in 2007, it was a typical steel mill structure. With no heat or insulation, inadequate ventilation and a black exterior skin, the temperature extremes inside were unbearable in the summer and winter months. While the temperature was more moderate in the spring and fall, it was dimly lit and as unpleasant inside as it was unattractive outside.

Despite its age and problems, the basic structure was in remarkably good condition and far superior to current building standards. With readily available utilities and services, the site was an excellent candidate for renovation. The design team’s challenge was not only to bring the site up to contemporary building and safety standards, but also to make it as energy-efficient as possible while maintaining as much of the original architectural character and craftsmanship as practical.

In its original condition, using conventional methods and 2006 fuel prices, the annual cost to heat the 6875-m2 (74,000-sf) building in the winter was estimated to be $350,000. A strong steel structure and thick concrete slab are positive attributes, but the uninsulated space with 20-m (65-ft) high interior volume created significant operation inefficiencies. There was also no effective method of moderating the dangerous summer heat.

The challenge was to find a way to provide a comfortable and safe environment for employees, while also reducing the operating overhead for the building. No single technology could address both needs and the solution came from a blend of carefully selected sustainable building materials and green technologies.

High R-value insulation was added to walls and ceilings. Daylight harvesting was achieved with the extensive use of high performance skylights. A rainwater harvesting system was implemented to significantly reduce the demand placed on municipal water, sewer, and storm water management systems. A Galvalume metal roof was installed, which has special ‘cool’ coatings, offering superior performance characteristics and extreme durability. Improving the appearance of the building, a new exterior metal skin also helped to reject the summer heat.

A total of 1084 m2 (11,670 sf) of black, transpired solar collector wall panels were installed on the building’s southern facing vertical surfaces. They both added aesthetic appeal to the structure, and serve as an integral part of the system that provides the primary source of heat in the winter.

The system collects heat from the sun and transfers it inside the building, even on the coldest winter days. It also provides passive cooling in the summer and fresh air exchange for a healthy interior environment year-round. In extreme winter conditions, the solar system is supplemented with heat from a high-efficiency natural gas fired system. With 20-m high ceilings, some mechanism to mix the air inside the building was necessary. Small, efficient destratification fans were used for this application.

The facility’s owner, Craig Cigas, explained actual fuel costs to heat this building in the first year were reduced to just $890 versus the projected $350,000.

“We turned a six-figure problem into a three-figure solution,” he said. “It’s an incredibly simple, yet effective, design that immediately appealed to me. Moreover, we were able to achieve a 12-month return on our investment.”

The industrial shed was harmonized with a superior workplace that resulted in reduced energy consumption, while offering employees better air quality. This helped move Cigas’ manufacturing operation to the forefront of green industrial facilities.

The renovation hit the mark, said project architect, Martin Breen, formerly with AP3C Architects and now with Philadelphia’s KDA Architects.

“The machine shop now has a contemporary aesthetic that represents the world-class manufacturing processes taking place inside,” he explained. “It stands out in the stark industrial landscape and is a shining example of how industrial facilities can be environmentally responsible.”

While the project did not pursue certification under the Leadership in Energy and Environmental Design (LEED), it still looked to the green building program for certain principles.

“Continuously searching for ways to apply LEED design guidance and sustainable technologies as they mature and come to market is not only the responsible thing to do, it’s the smart thing to do,” Cigas said. “We should all be thinking green and sharing what we learn.”

To read the full article, click here.

Solar Air-heating Systems 101: Ensuring efficient and economical renewable energy

All images courtesy ATAS International

All images courtesy ATAS International

by Lee Ann M. Slattery, CSI, CCPR, LEED AP

The cost of heating a building is a major expense for most building owners, and it is also a cost to the health and well-being of the general population in carbon pollution. By incorporating renewable energy technologies into the design and construction of a building, both these costs can be substantially reduced.

Building owners are seeking ways in which to reduce their energy consumption. According to the U.S. Environmental Protection Agency (EPA), the country’s buildings account for 36 percent of total energy use, and 30 percent of greenhouse gas (GHG) emissions.1 Existing and emerging renewable energy technologies are offering several methods in which to reduce both energy consumption and emissions. One example is a transpired solar collector—an air-preheating system that augments the building’s standard heating system.

The technology is quite simple and effective. Perforated metal wall panels in a dark color are installed several inches from a generally south-facing wall, creating an air space or plenum between the non-combustible watertight wall and the metal panel. Sunlight heats the air at the surface of the collector, and fans at the top of the plenum or in the air handling units (AHUs) draw the warmed air through the perforations into the plenum.

This heated air is distributed into the building, often through the existing HVAC system (Figure 1), or, in the case of a warehouse or manufacturing facility, distributed directly into the workspace (Figure 2). This simple and efficient system can be used on various building types, and is suitable for both new construction and retrofit projects.

A transpired solar collector system can also create healthy, productive indoor environments. In recent years, EPA’s Science Advisory Board has consistently ranked indoor air pollution among the top five environmental risks to public health, and there is mounting evidence that inadequate ventilation affects human performance.2 This finding applies to institutional buildings, such as schools, as well as offices, laboratories, and other commercial buildings. Requirements for outside air are established by various associations, code bodies, and government agencies. It is important to deliver enough fresh air, while maintaining a comfortable temperature within the building.

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Installation of a transpired solar collector
There are two primary requirements for the outer covering of exterior walls to which transpired solar collector panels are attached: an approved water-resistive barrier and an approved material for the plenum’s fire safety.

In other words, the covering must provide a drainage plane to prevent intrusion of liquid water to the interior of the wall assembly. The International Building Code (IBC) requires a water-resistive barrier be provided behind the exterior veneer for this purpose. For fire safety, the cavity between the transpired solar collector panels and the exterior of the main wall serves as a plenum that distributes ventilation air to the occupied space in the building. In terms of minimizing the spread of flames and the creation of smoke, this is of paramount importance. Requirements of various fire safety codes dominate this consideration.

Common building materials—such as metal panels, brick, or concrete masonry—meet both of these requirements. The most direct way to meet these requirements is by using a watertight, non-combustible material as the outer covering. The use of any alternative materials must be considered very carefully so neither assembly integrity nor occupant safety is compromised. Any alternative materials must be approved water-resistive barriers and also meet the minimum fire safety requirements for Underwriters Laboratories (UL) 181, Factory-made Air Ducts and Air Connectors, Class 1 materials.

Once it has been determined there is a proper watertight, non-combustible wall over which to install the transpired solar collector panels, the contractor is ready to begin panel installation. The panels are typically installed 100 to 200 mm (4 to 8 in.) from the existing wall, creating the air space (plenum). A series of vertical zees and horizontal hat channels are used to create the air space (Figure 3).

The panels can be installed over or around existing wall openings, and no special skills or tools are needed. Any excess moisture collected in the plenum drains out the bottom flashing assembly, and/or is naturally vented at the top of the system in the cooling season. The plenum is heated, which lowers relative humidity, and there are high ventilation rates in the heating season.

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Direct-to-space heating applications
Hangars, light manufacturing, maintenance garages, industrial buildings, and other large, open spaces often employ direct-to-space heating and ventilation systems. Some characteristics of these types of buildings include:

  • high ceilings;
  • heaters suspended from ceilings;
  • air exhaust fans in ceilings;
  • negative pressure (which draws in cold outside air); and
  • temperature stratification (hot air collects at ceilings).

A transpired solar collector system will heat make-up air for these buildings and provide a simple, economical approach to meet indoor air quality (IAQ) standards. This renewable energy technology benefits these facilities in three ways:

  1. Ventilation air is actively heated by solar energy.
  2. Heat loss through the wall is recaptured.
  3. Stratified heat at the ceiling is utilized at the working level.

Fan units are located at regular intervals along the wall near the roof to draw the preheated fresh air through the tiny perforations in the metal wall cladding. Each fan has modulating outside air and return dampers, discharge air temperature sensors and controls, and a flame-retardant duct that distributes the solar-heated air along the ceiling through numerous precision openings. When air is no longer required and the fan system is shut down, the outside air dampers close automatically.

As the fi rst net-zero energy transit center in the country, John W. Olver Transit Center (operated by the Franklin Regional Transit Authority in Greenfi eld, Massachusetts) incorporates a transpired solar collector.

As the first net-zero energy transit center in the country, John W. Olver Transit Center (operated by the Franklin Regional Transit Authority in Greenfield, Massachusetts) incorporates a transpired solar collector.

During the summer, when heating is not required, outside air can be brought directly into the distribution ducts through bypass louvers or through a separate inlet. As well, during the warmer months, cool evening air can be brought into the building using the system at night, so it is a much more comfortable environment for the employees in the building the following morning.

Ventilation air, destratification, and balanced ventilation
American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) 62, Ventilation for Acceptable Indoor Air Quality, is recognized as a foundation standard for IAQ. It states:

Indoor air should not contain contaminants that exceed concentrations known to impair health or cause discomfort to occupants.

Ventilation requirements for industrial facilities vary widely according to the type of process. Air change rates of one-half to four per hour are common. Heating these large volumes of air during cooler months can be expensive.

In a typical building, the temperature of the hot stratified air at the ceiling can rise to over 27 C (80 F) in winter. The air distribution fans and duct reclaim the stratified heat trapped at the ceiling by creating natural convection currents that carry the heat down to the working level for employee comfort.

With a lower ceiling temperature, heat losses through ceiling-mounted exhaust fans are reduced. At the same time, the constant supply of make-up air pressurizes the building, stopping infiltration of cold air around openings and reducing uncomfortable drafts along the floor. The controlled intake of fresh air also purges contaminants efficiently, eliminates high-velocity cross-drafts through windows and doors, and prevents down-draft in combustion flues. When system fans are running, a transpired solar collector can also have an insulating effect and recapture heat loss through the walls.

Several sustainable systems, including a transpired solar collector, contributed to Leadership in Energy and Environment Design (LEED) Silver certifi cation of Hampden Academy in Maine.

Several sustainable systems, including a transpired solar collector, contributed to Leadership in Energy and Environment Design (LEED) Silver certification of Hampden Academy in Maine.

A transpired solar collector contributed to credits in Sherwood Middle School—a Shrewsbury, Massachusetts facility enrolled in the Collaborative for High Performance Schools (CHPS) program.

A transpired solar collector contributed to credits in Sherwood Middle School—a Shrewsbury, Massachusetts facility enrolled in the Collaborative for High Performance Schools (CHPS) program.

Pre-heated replenishment air for institutional and commercial facilities
A transpired solar collector system is an excellent renewable energy source for schools, as well as office buildings and laboratories, for numerous reasons. For example, these types of buildings are occupied primarily during daylight hours when the sun is available for heating. Schools, in particular, operate during the coldest seasons when heating requirements predominate.

Fresh air helps students and employees learn and work better. Further, these buildings are long-term investments offering energy savings over many years. The installed cost of a system is comparable to that of a brick wall, with a typical payback period of three to eight years. Grants and other incentives for renewable energy projects may also offset costs.3

Each square foot of collector panel can heat 3.4 to 13.6 m3/hour (2 to 8 cfm) of air and provide 1 to 2 therms (100,000 to 200,000 Btus) of heating energy annually. Air temperature increases of 16.7 to 27.8 C (30 to 50 F) are common, and heating cost savings generally range from $16.15 to $59.20 per m2 ($1.50 to $5.50 per sf) of collector, depending on the fuel displaced. Annual energy savings are typically 20 to 40 percent or more. The panels have an approximate 30-year life and are virtually maintenance-free. Transpired solar collector panels with a polyvinylidene fluoride (PVDF) paint finish offer long-term color integrity and heat absorption values.

Perforated solar cladding can be seamlessly integrated into many architectural designs. Collector walls are most advantageously installed on south-facing walls, but east and west walls are also acceptable. Non-perforated panels can be used to unify design elements. Darker colors are better absorbers than lighter hues. As shown in Figure 4, different profiles of panels, with both horizontal and vertical installations, can be employed, with exposed or concealed fasteners (depending on the profile chosen) and mitered corners for the system are also available.

A solar air-heating wall assembly is an energy system that is custom-engineered per project. Building orientation, climate, and ventilation requirements are just some of the factors that must be considered. In most cases, a feasibility study is recommended to predict energy savings and define the construction details.

The Canadian government wrote a free, easy-to-use software program called RETScreen to determine the energy, environmental, and financial impact of these systems.4 Proprietary software is also used to fine-tune installations.

The technology for perforated solar air-heating systems was developed through extensive testing at the National Renewable Energy Laboratory (NREL) of the U.S. Department of Energy (DOE), and in Canada at the CANMET Energy Diversification Research Laboratory, an agency of Natural Resources of Canada (NRCan).

Project suitability
When designing a new building (or renovating an existing one), a transpired solar collector may assist in the solution of design challenges such as:

  • reducing energy consumption and air pollution;
  • minimizing maintenance;
  • heating with a cost-effective supplemental system;
  • maximizing use of renewable, non-polluting fuel; and
  • ventilating with preheated fresh air.

More specifically, modular transpired solar collector units can be used for drying agricultural produce such as herbs, spices, and coffee beans. Modular units can be mounted on a roof, wall, or the ground. They can assist in obtaining fuel savings in the drying process, extending the life of drying equipment and improving control of moisture content reduction.

Another use for a transpired solar collector is to heat barns. Young pigs, turkeys, and broiler chicks require a substantial amount of supplemental heat because they cannot produce enough body heat themselves. A transpired solar collector system serves this purpose, efficiently and economically.

There is the possibility for other unique applications. This author knows of a commercial dive shop in Southern California that installed the solar collectors on their building to accelerate the drying of wetsuits hung inside of that south-facing wall.

Of course, these assemblies are also often employed in office buildings and educational settings. The use of a solar air-heating wall system improves the building environment for occupants by providing solar pre-heated ventilation air. The system reduces heating energy costs and carbon footprints, and therefore may contribute to credits under the U.S. Green Building Council’s (USGBC’s) Leadership in Energy and Environmental Design (LEED) program:

  • Energy and Atmosphere (EA) Credit 1, Optimize Energy Performance;
  • EAC Credit 2, Onsite Renewable Energy;
  • Materials and Resources (MR) Credit 4, Recycled Content;
  • Indoor Environmental Quality (EQ) Credit 1, Outdoor Air Delivery Monitoring;
  • EQ Credit 2, Increased Ventilation;
  • EQ Credit 7.1, Thermal Comfort−Design; and
  • EQ Credit 7.2, Thermal Comfort−Verification.

All these benefits, based on free energy from the sun, can translate to financial savings and an improved working environment.

Notes
1 Visit www.epa.gov/oaintrnt/projects. (back to top)
2 Visit www.epa.gov/smokefree/pubs/etsfs.html. (back to top)
3 Funded by the U.S. Department of Energy (DOE), the Database of State Incentives for Renewable Energy Visit (DSIRE) is a comprehensive source of information on incentives and policies that support renewables and energy efficiency in the United States. Established in 1995, it is currently operated by the N.C. Solar Center at North Carolina State University, with support from the Interstate Renewable Energy Council. Visit www.dsireusa.org. (back to top)
4 Visit www.retscreen.net. (back to top)

Lee Ann M. Slattery, CSI, CCPR, LEED AP, is the sales support manager for ATAS International, and president of the CSI Allentown Chapter. Specializing in the architectural building materials industry for the past 22 years, she has worked with architects, specifiers, engineers, contractors, facility managers, property owners, and distributors. Slattery also assists in the development and maintenance of ATAS’ continuing education programs. She can be reached at lslattery@atas.com.

To read the case study on the Cigas Machine Shop, click here.

Thermoformed Ceiling Panels and Tiles: Drop-out Ceiling Panels Installed Beneath Fire Sprinklers

Approved drop-out ceiling panels can be installed beneath fire sprinklers. When exposed to heat from a small fire, drop-out ceiling panels soften, distort, and fall from ceiling grid. Heat from the growing fire activates sprinklers that, unimpeded by panels that have dropped out, controls or extinguishes the fire.*

Drop-out ceiling panels have several significant advantages compared to conventional ceiling panels. They are able to:

  • hide sprinklers to reduce visual clutter on the ceiling;
  • protect sprinklers against tampering and accidental knocks and the resulting water damage;
  • simplify sprinkler design at ceiling clouds and other design features by locating sprinklers above dropped ceiling; and
  • remain cost effective, eliminating need to ‘drop’ sprinklers, simplifying alignment with panel centers and coordination with ceiling installation, and allowing use of less costly, non-appearance grade sprinklers.

Codes and standards
Use of drop-out ceiling panels is governed by local building and fire codes that address acceptable interior finish elements like ceiling panels. The International Building Code (IBC) is often used as the model building code on which many building codes are based. IBC covers interior ceiling panels in Chapter 8 and addresses fire sprinklers in Chapter 9. When requiring fire sprinkler systems, IBC refers to National Fire Protection Association (NFPA) 13, Standard for the Installation of Sprinkler Systems. This standard addresses drop-out ceilings in Section 8.15.15 (2013 Edition), permitting their installation beneath sprinklers where ceilings are listed and installed for that service. Similarly, NFPA 13R, Standard for the Installation of Sprinkler Systems in Low-rise Residential Occupancies, permits drop-out ceilings in Section 6.15.

NFPA does not approve, inspect, or certify drop-out ceiling panels. Instead, the authority having jurisdiction (AHJ) refers to listings maintained by organizations—such as IAPMO-UES, Factory Mutual (FM Global), International Code Council Evaluation Service (ICC-ES), CertMark, and Underwriters Laboratories (UL)—that evaluate products for compliance with appropriate standards.** As the AHJ has final approval authority, they should be contacted early in the design phase to get their input and address concerns.

Occupancy
Design of a drop-out ceiling system generally begins with identification of building occupancy. Listings from some agencies recognize drop-out panels in both Light Hazard and Ordinary Hazard Group 1 occupancies. FM, however, only recognizes drop-out panels in light hazard occupancies. Listings should always be checked to confirm where proposed ceiling panels may be used. Additionally, the organization issuing the evaluation report must be acceptable to your AHJ.

Light hazard occupancies are where combustibility or quantity of contents is low and fires with relatively low heat release are expected. Examples of light hazard occupancies are:

  • animal shelters;
  • churches;
  • libraries (except large stack);
  • museums;
  • offices;
  • recreational facilities;
  • restaurant seating areas; and
  • theaters (except stages).

Ordinary Hazard Group 1 occupancies are where combustibility of contents is low, the quantity of combustibles is moderate, stockpiles do not exceed 2.4 m (8 ft), and fires with moderate rates of heat release are expected. Examples include:

  • auto showrooms;
  • food manufacturing and processing;
  • electronic plants and similar light manufacturing facilities; and
  • laundries.

While typical dairy processing facilities are appropriate for drop-out ceiling panels, this would not pertain where significant quantities of cardboard packaging are stored.

Ordinary Hazard Group 2 occupancies are not recommended for drop-out ceiling panels. These include manufacturing occupancies used for plastic fabrication, wood working, and machining, and mercantile occupancies used for display and sale of merchandise. However, the AHJ may have latitude to accept drop-out ceilings if stockpiles of combustibles are limited, consist of materials with low rates of heat release, and have low probability of rapidly developing fires. A pottery store with these characteristics might be appropriate for drop-out ceilings and acceptable to the AHJ despite being a mercantile occupancy due to incombustibility of the merchandise.

Residential occupancies permit drop-out ceiling panels under NFPA 13 and 13R. Drop-out ceilings can be used in combination with either standard-response, 74 C (165 F) or higher sprinklers or quick-response, 68 C (155 F) or higher sprinklers. Residential-type sprinklers are not acceptable with drop-out ceiling panels.

When remodeling an existing building, the fire sprinkler riser should be located and its hydraulic nameplate data for occupancy classification checked. This information may help the AHJ help determine whether a drop-out ceiling is appropriate.

Sprinkler types
Next is selection of sprinkler types. All drop-out panels currently available have been evaluated for use with standard-response sprinklers that have a thermal element with an Response Time Index (RTI)—a measure of thermal sensitivity—of more than 50 (meter-seconds)1/2. One brand of drop-out panels has been recently listed for use with quick-response sprinklers (see IAPMO-UES Evaluation Report 0310. This is significant as quick-response sprinklers have been required in light hazard occupancies since 1996 edition of NFPA 13. Quick-response sprinklers have an RTI of 50 (meter-seconds)1/2 or less. No drop-out panels have been approved with extended coverage, residential, dry-pipe, or other types of sprinkler systems.

Sprinklers must be installed in compliance with NFPA requirements, including avoidance of obstructions by structural elements, HVAC ducts, and other above-ceiling elements. Evaluation reports specify allowable sprinkler heights above ceiling panels and require identification of report on packaging. Examples based on a listed vinyl drop-out panel include:

  1. Standard-response sprinklers rated 74 (165 F) or higher can be installed from 25 to 1524 mm (1 to 60 in.) above ceiling panels.
  2. Quick-response sprinklers rated 68 C (155 F) or higher require sprinklers installed 25 mm (1 in.) or less from top of standard T-bar ceiling grid. Verify that proposed ceiling panel can be installed within this clearance.

Inappropriate applications
Finally, conditions precluding drop-out ceilings include:

  1. Use in exits such as corridors, stairways, horizontal exits, pressurized enclosures, and exit passageways as defined in IBC Chapter 10.
  2. Sprinklers installed both above and below panels.
  3. Insulation between ceiling panels and sprinklers. (Insulating backer panels in specific listings are an exception.)
  4. Panels are not Class A rated.
  5. Ceiling is required to protect sprinkler piping such as soft-soldered copper pipe or combustible plastic pipe. (Drop-out ceiling will not provide concealment as it drops-out early in fire.)
  6. Ceiling is part of fire-resistance rated assembly. (Drop-out ceilings can be installed below rated assembly but cannot be part of assembly.)
  7. Space above ceiling is air circulation plenum.
  8. Ceiling is non-horizontal.
  9. Structure is floating or waterborne.
  10. Ceiling suspension system does not comply with listing.
  11. Clips prevent downward movement of panels. (Uplift prevention clips are permitted but not required.)
  12. Drop-out ceiling panels are used as diffusers within light fixtures.

Maintenance
Building owner must maintain sprinkler and ceiling systems. Drop-out panels beneath sprinklers cannot be painted. If it becomes necessary to replace drop-out panels the new ones should be of same type as originally installed or another type approved for installation beneath sprinklers. Some drop-out ceiling panel manufacturers offer signage reminding building users to replace panels in kind; signage can be posted at sprinkler alarm valve (next to hydraulic nameplate) or another conspicuous location.

* For more information, see “Drop-out Ceiling Panels–A Discussion on Their Use With Fire Sprinklers,” a white paper by Gary G. Piermattei, RFPE, PE, senior consultant at Rolf Jensen & Associates.
**See, for example:

  • CertMark International: CMI Evaluation Report CER-3101;
  • FM Approvals–Suspended Plastic Ceilings (Class Number 4651) Approval Guide;
  • IAPMO Uniform Evaluation Service (IAPMO-UES): Evaluation Report 0310;
  • ICC Evaluation Service (ICC-ES):Evaluation Report ESR-2451; and
  • Underwriters Laboratories (UL): Product Listing BLME.R4036.

Light-transmitting plastics for luminous ceilings are regulated by IBC Chapter 26.

To read the full article, click here.

Thermoformed Ceiling Panels and Tiles

All images courtesy Ceilume

All images courtesy Ceilume

by Ed Davis, David Condello, CSI, and Michael Chusid, RA, FCSI, CCS

Plastic has been frequently used for floorings and wallcoverings, but not for ceilings. This is changing as thermoformed plastic ceiling panels and tiles have proven their mettle in rigorous testing and through approvals and listings by building product evaluation services.

While ceilings can be made with various types of plastic and in myriad configurations, this article discusses ceiling elements made from rigid vinyl or polyethylene terephtalate (PET) sheets 0.33 or 0.76 mm (0.013 or 0.03 in.) thick, that are thermoformed to create decorative surfaces. Forming also imparts depth to the thin material, sufficiently stiffening panels to span between conventional ceiling suspension grid members.

Ceilings of this type have been manufactured since the mid-20th century and have been improved with refinements in materials, fabrication techniques, and finishes. They now provide a unique constellation of characteristics making them suitable for various architectural and building applications.

This article uses ‘tile’ to mean a ‘ceiling element used with concealed or semi-exposed suspension systems, stapling, or adhesive bonding’ and ‘panel’ as a ‘ceiling element used with exposed suspension systems.’1 Since standards and manufacturers do not use terms consistently, construction documents should define terms used for particular projects.

Fire safety
It is appropriate to consider fire safety first because of plastic’s combustibility. Thin plastic has such little mass it provides no significant fuel load relative to the other combustible materials in a building.2 Surface burning characteristics are more relevant to life safety; there are now Class A thermoformed ceilings that, with certain limitations, can be specified for all but the most critical occupancies.3

Ceilings can be made from plastic rated V0 under Underwriters Laboratories (UL) 94, Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances Testing. Such materials are self-extinguishing—flaming combustion stops within 10 seconds after removal of heat source, glowing combustion stops within 30 seconds, and materials do not drip flaming particles that could ignite cotton.4

Unlike most types of ceilings, some thermoformed assemblies can be installed above or beneath fire sprinklers without interfering with sprinkler function when used in accordance with listings and approvals. When exposed to heat from a fire, panels soften, deform, and drop out of suspension grids at temperatures well below the activation point of commonly used sprinklers.

Ceilings beneath sprinklers
Referred to as ‘drop-out ceilings,’ thermoplastic ceiling panels can simplify sprinkler installation and significantly reduce construction costs.5 Sprinklers are not visible from below, making ceilings less cluttered and more attractive, while also protecting sprinklers against accidental impact or tampering and the water damage that results from sprinkler inactivation. Drop-out ceilings can be especially useful for suspended ceiling ‘clouds’ that could otherwise require sprinklers to be located both above and below the cloud. (See “Drop-out Ceiling Panels Installed Beneath Fire Sprinklers.”)

One glance at a thermoformed ceiling speaks immediately to the decorative potential of the molded panels and tiles. What is not seen, however, can be even more important—these panels can be installed beneath fire sprinklers to keep the ceiling surface uncluttered.

One glance at a thermoformed ceiling speaks immediately to the decorative potential of the molded panels and tiles. What is not seen, however, can be even more important—these panels can be installed beneath fire sprinklers to keep the ceiling surface uncluttered.

Lightweight and easily installed, thermoformed panels and tiles can be trimmed with scissors or aviation snips. Although the products are made with thin material, panels and tiles are robust, do not release fi bers, and are not frangible.

Lightweight and easily installed, thermoformed panels and tiles can be trimmed with scissors or aviation snips. Although the products are made with thin material, panels and tiles are robust, do not release fibers, and are not frangible.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ceilings above sprinklers
To avoid falling panels from getting hung-up on sprinklers and preventing their operation, pendent-style sprinklers must be installed through over-sized openings in panels.

Installed with or without sprinklers, drop-out panels regain stiffness when they fall to the relatively cooler floor. Since they are thin and light, they do not significantly impede egress or access by firefighters. Building product evaluation services, however, have not approved use of drop-out ceilings in exits or stairs.

These comments about fire safety apply only to thermoformed ceiling products tested and approved by reputable organization such as UL, IAPMO Uniform Evaluation Service, International Code Council Evaluation Service (ICC-ES), CertMark, and Factory Mutual (FM).

For many designers, the best-looking fire sprinkler is the one that is not there. Sprinklers can be installed above approved thermoformed ceilings (top) or no more than 24 mm (1 in.) beneath surface (bottom). Holes for penetrating sprinklers must be oversized to allow panels to drop-out without draping over sprinkler in the event of a fire.

For many designers, the best-looking fire sprinkler is the one that is not there. Sprinklers can be installed above approved thermoformed ceilings (top) or no more than 24 mm (1 in.) beneath surface (bottom). Holes for penetrating sprinklers must be oversized to allow panels to drop-out without draping over sprinkler in the event of a fire.

Thermoformed ceiling tiles and panels can be used in humid areas such as above the hot tub. The decorative molded pattern suggests ripples in water. During day, side light entering from glazed wall enhances relief with shadows and highlights; at night, the ceiling is back-lit. Border tile with low relief are used around perimeter of space.

Thermoformed ceiling tiles and panels can be used in humid areas such as above the hot tub. The decorative molded pattern suggests ripples in water. During day, side light entering from glazed wall enhances relief with shadows and highlights; at night, the ceiling is back-lit. Border tile with low relief are used around perimeter of space.

 

 

 

 

 

 

 

 

 

 

Moisture, mold, and hygiene
Vinyl and PET ceilings are not affected by moisture and can be used in wet or humid locations. Examples include natatoria, shower and bathing rooms, spas, laundries, kitchens, and areas subject to washdown.6 Moisture resistance is also a concern in normally dry spaces due to ever-present risks of roof and plumbing leaks, dripping condensate from sweating pipes, HVAC equipment, and spills.

Moisture resistance is closely associated with mold resistance. Thermoformed ceilings neither hold the moisture required for fungal growth nor provide a source of nutrition.

In flood-prone areas, thermoformed ceiling panels meet Federal Emergency Management Agency (FEMA) Class 4 requirements for materials that:

can survive wetting and drying and may be successfully cleaned after a flood to render them free of most harmful pollutants. Materials in this class may be exposed to and/or submerged in floodwaters in interior spaces and do not require special waterproofing protection.7

In suspended ceilings, uplift prevention clips reduce the likelihood panels will be dislodged.

Moisture resistance makes it feasible to install thermoformed ceiling elements before humidity in a building has stabilized. This feature helps meet project deadlines because ceiling installation is frequently delayed until the end of a construction project. Plastic’s moisture resistance abets final cleaning of a jobsite because vinyl and PET are easy to clean.

This is important in areas requiring good hygiene. Thermoformed ceiling elements can be cleaned with a damp cloth and, if necessary, mild detergent or compatible cleaning agents. This makes them practical in culinary and food-manufacturing areas where government regulations require smooth, durable, easily cleanable, and non-absorbent surfaces. To meet these requirements, panels or tiles with low surface-relief patterns should be used.8 Thermoformed ceilings also promote hygiene by allowing above-ceiling installation of lighting fixtures and fire sprinkler devices that can collect contaminants.

While standardized stain-resistance tests have not been conducted on some thermoformed ceilings, their long record of use demonstrates plastic’s resistance to the grime and stains that typically disfigure ceilings. For example, the proprietor of a cigar lounge told one of these authors thermoformed ceiling elements in his establishment do not absorb odors from tobacco smoke, and stains can be removed by washing.

Many healthcare, veterinary, laboratory, and industrial facilities also require hygienic ceilings. Since plastic ceilings are impermeable and fiber-free, they can also be considered for cleanrooms.

Computer server farms illustrate how thermoformed ceiling products can solve a complex set of requirements. Cool air is typically fed into server racks to keep equipment within an optimal operating temperature range. Instead of releasing heated air into the surrounding room, aisles between racks are enclosed to act as plenums for exhaust air. By using translucent, drop-out panels as above-aisle ceilings, light fixtures and fire sprinklers can be located above server banks where they will not interfere with access to servers.

Computer server farms illustrate how thermoformed ceiling products can solve a complex set of requirements. Cool air is typically fed into server racks to keep equipment within an optimal operating temperature range. Instead of releasing heated air into the surrounding room, aisles between racks are enclosed to act as plenums for exhaust air. By using translucent, drop-out panels as above-aisle ceilings, light fixtures and fire sprinklers can be located above server banks where they will not interfere with access to servers.

Thermoformed panels and tiles come in a range of patterns and fi nishes.

Thermoformed panels and tiles come in a range of patterns and finishes.

 

 

 

 

 

 

 

 

 

 

 

 

 

Acoustics
Installed in a suspended grid, thin thermoformed panels act as diaphragms that transfer sound from occupied spaces to above-ceiling cavities where vibrations can be absorbed or dissipated. To simulate this condition, suspended ceilings are tested under ASTM C423, Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberation Room Method, using Mounting E with a 400-mm (16-in.) deep cavity between panels and concrete surface of reverberant test chamber.9

In this condition, thermoformed panels 0.33 mm (0.013 in.) thick have a noise reduction coefficient (NRC) of 0.25 or 0.30. This increases to NRC 0.35 to 0.45 when paired with special backer panels—inverted pans made of 0.33-mm (0.013-in.) thick plastic that nest above ceiling panels to form 76-mm (3-in.) deep air pockets that dampen vibrations.

Given the moderate acoustical performance of most suspended ceilings, ranging from NRC 0.05 for plaster and gypsum board to 0.55 or better for mineral fiber products, thermoformed panels are suitable for various commercial, residential, and institutional occupancies. However, when glued or stapled to a solid surface, thermoformed tiles provide insignificant noise reduction.

Thermoformed ceiling panels complement the panelized wood walls and doors to enhance the decorative motif of this cigar lounge. The ceiling panels do not absorb odors from cigar smoke and can be washed to remove tobacco stains.

Thermoformed ceiling panels complement the panelized wood walls and doors to enhance the decorative motif of this cigar lounge. The ceiling panels do not absorb odors from cigar smoke and can be washed to remove tobacco stains.

Faux wood grain and molded surface of ceiling add to the charm and down-home comfort of a café. Thermoformed ceiling tiles can extend over culinary areas because hygienic surfaces meet Food & Drug Administration (FDA) requirements for food-handling facilities.

Faux wood grain and molded surface of ceiling add to the charm and down-home comfort of a café. Thermoformed ceiling tiles can extend over culinary areas because hygienic surfaces meet Food & Drug Administration (FDA) requirements for food-handling facilities.

Lighting
Available in three levels of optical transmissivity, thermoformed ceiling panels facilitate creative approaches to lighting.

Opaque white panels have a bright light reflectance value (LRV) of approximately 83.10 This takes on special significance with directional light sources that cast shadows on the molded relief of panels and tiles.

Translucent white plastic is used for backlit luminous ceilings. Panels that are 0.33 mm (0.013 inch) thick have light transmittance of more than 50 percent; this is reduced to approximately 40 percent when used with acoustical backer panels. Backer panels have a frosted surface that diffuses above-ceiling light sources for more uniform illumination below. Additionally, backers reduce shadows caused by detritus that would otherwise accumulate directly on top of ceiling panels. Translucent ceilings can be used with light-emitting diode (LED) lamps to create glowing illumination that can be programmed to change colors.

Transparent panels allow light fixtures to be placed above a ceiling while maintaining the continuity of the surface’s plane and pattern.11 For example, a light fixture with a directional beam can be placed above the ceiling—and out of sight—yet still focused on a piece of artwork or other visual feature. They are also practical in areas where hygiene or other considerations make it desirable to keep light fixtures isolated. For example, federal regulations require food preparation areas to be protected against contamination from breakage of overhead lamps, skylights, and other glass.

Several levels of transmissivity can be combined as required. In a hotel lobby, opaque panels can be used with uplighting at seating areas, translucent panels to create a luminous ceiling above the registration counter, and transparent panels below spotlights creating visual excitement above the dance floor in a bar. Daylight, as an energy conservation strategy, also suggests applications for translucent and transparent panels beneath skylights for opaque or translucent panels and as light shelves to direct light more deeply into buildings.

Sustainability
Many of the already enumerated characteristics of thermoformed ceilings contribute to building sustainability, such as:

  • lighting efficiency;
  • noise reduction;
  • cleanability; and
  • fungal resistance.

In terms of material choices, some industry leaders advocate against vinyl, also known as polyvinyl chloride (PVC). Vinyl is made from petrochemicals, has problematic precursor products, and may release toxic products of combustions if burned. Other authorities remind us of vinyl’s long service life and low maintenance requirements which mitigate some of these concerns. Reputable manufacturers now use vinyl produced through cleaner technologies and without the most egregious additives. Combustion risks are reduced by considerations mentioned, and vinyl is recyclable as a Type 3 plastic.

Environmental Building News, an arbiter of sustainable design, suggests, “For builders and architects, our recommendation is not to avoid vinyl altogether, but to seek out better, safer, and more environmentally responsible alternatives.”12

Reasoning like this has led to an increased use of recycled PET (rPET) for ceilings with as much as 40 percent post-consumer recycled content. While PET has a greener environmental rap sheet—raw material costs more than vinyl—it is more difficult to fabricate in certain ceiling styles, and it is not yet approved for use below sprinklers. While vinyl has demonstrated longevity in building applications, PET service life has yet to be determined. PET is recyclable as Type 1 plastic.

Both vinyl and PET are available with GreenGuard’s Gold certification of compliance with California’s Department of Public Health Services Standard Practice for Specification Section 01350 (i.e. California Section 01350) for low chemical emissions from building products used in schools, healthcare, and other critical environments. Indoor air quality (IAQ) is also protected because the plastics are fiber free and hygienic.

While sufficiently rigid to maintain visual flatness once installed, both vinyl and PET:

  • are resilient enough to flex during installation and maintenance;
  • are not frangible;
  • resist moderate abuse without breakage;
  • contain ultraviolet (UV) inhibitors; and
  • are cleanable.

Thermoformed ceilings weigh as little as 0.49 kg/m² (0.10 psf)—approximately 80 percent less than mineral fiber ceilings. This represents a significant reduction of manufacturing resource requirements. Additionally, transportation impacts are reduced because panels and tiles are lightweight, thin, and nest for compact packing. Five times as many panels can fit on a truck compared to 19-mm (3/4-in.) thick mineral fiber panels.

Appearance
While this article has discussed physical and performance properties, selection of thermoformed ceilings frequently begins with aesthetic considerations. Ceilings are often the most visually prominent surface of a room; the flat plane and rectangular grid of standard acoustic ceilings, once the hallmark of ‘modern’ efficiency, now epitomizes the ‘less is a bore’ sentiment of many designers. Thermoformed ceiling panels and tiles are available in dozens of styles ranging from historic stamped tin patterns and classic coffers to contemporary geometric and multifaceted panels and from shallow profiles to relief extending as much as 76 mm (3 in.) above or below the ceiling grid. Additionally, digital fabrication techniques have lowered the cost of making molds for custom patterns.

Some styles can be installed upside-down; while the pattern remains the same, inverted panels change the relationship of shadow and highlight to engage the viewer. Other design options include white, solid colors, faux metallic finishes, and faux wood grain finishes.

When a style with deep relief is used, it is customary to use border panels or tiles with low relief around ceiling perimeters. Alternatively, adventurous designers can achieve interesting effects by expressing the panel or tile profile at the ceiling perimeter.

Installation
Installation of thermoformed ceiling panels and tiles is similar to other materials. Lay-in panels can be used with standard suspension systems with 24-mm (15/16-in.) wide tees.13 Fiberglass, plastic, or aluminum suspensions should be considered in wet areas. Direct-mounted tiles install easily with construction-grade adhesives or staples. Panels are available for both 609 x 609-mm (2 x 2-ft) and 609 x 1218-mm (2 x 4-ft) grids.

The lightweight panels and tiles are less likely to cause injury due to lifting or dropping.14 They lack sharp edges and installers do not have to wear respirators. The material can be easily cut with scissors or aviation snips. Decorative strips are available, if desired, to trim butt joints between tiles.

Conclusion
It is crucial to verify the approvals and listings of proposed products because not all thermoformed ceiling products rise to the same standards. While thermoformed panels and tiles are widely used in simple do-it-yourself applications, design professionals may want assistance from a reputable manufacturer to identify suitable products for projects with more demanding requirements.

Through thermoformed ceiling panels and tiles can be used for any one of their several beneficial characteristics, it is when these innovative products are able to meet several requirements simultaneously that plastic can be transmuted into gold.

Notes
1 These definitions are from ASTM E1264, Standard Classification for Acoustic Ceiling Products. (back to top)
2 IBC Section 803.2, “Thickness exemption,” exempts ceiling finish materials less than 0.09 mm (0.036 in.) thick from fire performance and smoke development testing. While the IBC section applies only to materials directly applied to the surface of walls and ceilings, it establishes thin materials have insignificant fuel load. (back to top)
3 Class A finishes have flame spread ≤ 25 and smoke developed ≤ 450 tested under ASTM E84, Standard Test Method for Surface Burning Characteristics of Building Materials. (back to top)
4 For more on UL 94, see www.ides.com/property_descriptions/UL94.asp. (back to top)
5 In a detailed estimate examined construction costs for a 10,219-m2 (110,000-sf) office building in Oklahoma City 0.6 x 0.6-m (2 x 2-ft) plastic ceiling panels with acoustical backer and concealed (above-ceiling) sprinklers saved $3.30 per sf when compared to the same size ¾-in. mineral fiber ceiling panels with visible (recessed) sprinklers. (back to top)
6 Hold-down clips should be used when the ceiling will be directly sprayed with water. (back to top)
7 See FEMA’s Flood Damage-Resistant Material Requirements for Buildings Located in Special Flood Hazard Areas under the National Flood Insurance Program (Technical Bulletin 2–2008) at www.fema.gov/media-library/assets/documents/2655. (back to top)
8 See U.S. Food and Drug Administration’s (FDA’s) 2013 Food Code and Code of Federal Regulations at www.fda.gov/downloads/Food/GuidanceRegulation/RetailFoodProtection/FoodCode/UCM374510.pdf. (back to top)
9 See ASTM C423, Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberation Room Method. (back to top)
10 See ASTM E1477, Standard Test Method for Luminous Reflectance Factor of Acoustical Materials by Use of Integrating-Sphere Reflectometers. (back to top)
11 Transparent plastic may show distortions due to molding process. (back to top)
12 See www2.buildinggreen.com/article/should-we-phase-out-pvc. (back to top)
13 See ASTM C635, Standard Specification for the Manufacture, Performance, and Testing of Metal Suspension Systems for Acoustical Tile and Lay-in Panel Ceilings and ASTM C636, Standard Practice for Installation of Metal Ceiling Suspension Systems for Acoustical Tile and Lay-in Panels. (back to top)
14 Sharp edges are especially a problem with stamped metal ceilings. (back to top)

Ed Davis is president of Ceilume, a manufacturer of thermoformed ceiling panels, and has been responsible for product testing and obtaining product evaluations and approvals. He can be reached at ed@ceilume.com.

David Condello, CSI, has more than 20 years of experience in construction and is the architectural services manager for Ceilume. He can be reached at david@ceilume.com.

Michael Chusid, RA, CCS, FCSI, is an architect, a Fellow of CSI, and a Certified Construction Specifier. He is a frequent contributor to The Construction Specifier, and a consultant to building product manufacturers. He can be reached at www.chusid.com.