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.

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.

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.

Leave a Comment


Your email address will not be published.