Why fire sprinklers belong above suspended drop-out ceilings

The thermoformed panels have molded decorative relief and are available in a variety of colors, faux finishes, and light transmitting materials. They are approved for use with acoustical backings that provide noise reduction values as high as NRC = 0.85. They are Greenguard Gold certified for low volatile organic compound (VOC) emissions, made with up to 100 percent recycled-material content, and disclose ingredients in a Health Product Declaration. The panels are lightweight, easy to install, durable, strong, stain resistant, unaffected by water, and washable.

Expanded polystyrene (EPS) panels

Drop-out ceiling panels made from EPS foam are typically called ‘melt-out ceilings.’ The fact EPS melts complicates their fire-safety performance. The EPS Industry Alliance states, “When installed correctly, expanded polystyrene products do not present an undue fire hazard.” It also recommends, however, “…that expanded polystyrene should be protected by a thermal barrier in specific applications as referenced in [applicable codes].” This limit the occupancies in which EPS ceiling panels can be used.

As heat from the fire in this test chamber increased, thermoformed ceiling panels softened and dropped out of the suspension grid. This exposed the sprinkler so it could discharge when the appropriate temperature was reached and allowed water to extinguish the fire.. Photo courtesy Ceilume

Nonetheless, some EPS panels are listed by insurance companies based on testing in accordance with UL 723S Drop-Out Ceilings Installed Beneath Automatic Sprinklers. They have either a flat or molded white surface. The 16 kg/m3– (1 pcf-) density foam from which they are made has limited strength or durability. They do not offer noise reduction value and can be used only with standard response sprinklers.

Stretched ceilings

These ceilings use fabric that is stretched to provide a taut, flat ceiling surface that is held in place with perimeter gripping devices. The fabric panels are assembled with heat-sensitive stitches or seams. When exposed to heat, the seams become undone and tension in the stretched ceiling pulls the seams apart to expose sprinklers.

Some manufacturers use panels of translucent polypropylene fabric to make suspended covers that protect interior spaces from dust and contamination generated by reroofing or other overhead work. The fabric can also be used to form temporary partitions to create isolation areas for operations needing segregation from the rest of a space. These products are tested according to UL 723S and have an IAPMO-UES evaluation report recognizing its use as a drop-out ceiling. The report limits the product to temporary use of up to 180 days. Each installation is engineered and installed by the product’s manufacturer (Figure 7).

Several companies offer fabric systems used primarily in theatrical and exhibition installations. They use woven, synthetic textiles with fusible seams 305 mm (12 in.) on center. When the fabric reaches 71 C (160 F), the stretched knit contracts into small, bunched lines of material. This opens more that 70 percent of the ceiling area allowing heat to reach the sprinklers. Products in this category claim flame resistance but do not offer code evaluations regarding drop-out performance; consult authorities having jurisdiction for applicability to ceiling use.

While stretched fabric ceilings can be pulled back for access above the ceiling, they do not provide access as easily as panels in a ceiling grid. On the other hand, the stretchability of the fabrics allows for a modicum of curved surface and interesting architectural effects. Some of the fabric products can be easily printed upon to create stunning graphics.

Electro-mechanical operations

There are also ceiling panels that drop-out when an electro-mechanical latch releases in response to an electronic signal. While more expensive than the other options, they are useful where the ceiling must drop-out due to smoke detection or other trigger besides temperature rise.

Specifying tips

Each drop-out ceiling product has distinct characteristics, making it imperative to study its code evaluation service report or listing and the manufacturer’s installation instructions. Having the evaluation service report or listing will not only guide specification and installation, but it will also be invaluable if a building or fire authority having jurisdiction has questions about a product.

Each type of drop-out ceiling is compatible with only certain types of fire sprinklers and will have limits regarding the maximum and minimum height of the sprinklers above the ceiling. Further, they can be used only in the types of building occupancies included in the listing.

Unless otherwise permitted in a listing, drop-out ceilings should not be used in stairs, exit corridors, or paths of egress. Neither should they be used above nor adjacent to stoves, ovens, or other hot equipment. They cannot be part of a fire-resistance rated floor-ceiling assembly or an air distribution plenum. Further, they may be inappropriate for spaces requiring a high degree of sound isolation; the best available sound transmission classification for a drop-out ceiling is STC 18.

Ceiling products used for drop-out ceilings can also be used with penetrating sprinklers but may require special provisions to prevent ceiling panels from getting hung-up on and interfering with the operation of sprinklers in the event of a fire. There are two methods, for example, for using penetrating sprinklers with certain thermoformed panels:

∞ Sprinklers are installed through holes 6 mm (0.25 in.) larger in diameter than the outer diameter of the sprinkler and trim ring (if used) to enable tiles to fall from the ceiling grid without becoming entangled with the sprinkler, or

∞ 0.76-mm (0.03-in.) thick panels backed by mineral fiber panels can be used with penetrating sprinklers when installed in accordance with instructions.

Listings typically impose requirements for the type of suspension grid and installation accessories, prohibit painting of surfaces, and stipulate other conditions of use.

Project specifications should cross-reference the ceiling and sprinkler sections. It may be helpful to note the use of drop-out ceilings on project drawings to make sure bidders are aware of the applicable requirements.

Building owners and tenants must understand drop-out panels removed from a ceiling may be replaced only with another drop-out panel. Plaques stating this requirement should be installed in visible locations above the ceiling or at the sprinkler riser.

Successful use of a drop-out ceiling depends on communication among project designers and engineers. The former may be primarily concerned about ceiling aesthetics and performance, the latter with the layout and code compliance of the fire suppression system. Too often, the project team defaults to penetrating sprinklers without considering other options. They—and the building owner—may find the benefits of drop-out ceilings justify their consideration during the design development or early construction document phases of design.


Ed Davis is president of Ceilume, a leading manufacturer of thermoformed ceilings. He leads their fire testing and code approval efforts.


Ben Carr is the customer service manager at Ceilume and has 16 years of experience helping customers find ceiling solutions. He can be reached at pro@ceilume.com.


Michael Chusid is an architect and Fellow of the Construction Specifications Institute (CSI) and a marketing consultant to building product manufacturers.

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