Jan 2013

Fiber Reinforced Plastic Panels Used in Construction

Fiber reinforced plastic (FRP) panels, sometimes referred to as glassfiber reinforced plastic (GRP) panels, is a composite material made up a polymer matrix reinforced with fibers. The fibers are typically glass, but carbon, basalt, cellulose and asbestos have also been used. The polymer matrix usually is usually polyester resin, though other thermosetting plastics have been used. In construction, it is used primarily as an interior panel; its advantages include:

  • Scratch resistant surface due to its texture
  • Its ability to be easily cleaned
  • Resistant to stains, mold and mildew

The concern for this product is that if designed or installed in certain methods it will allow flame spread across its surface to be rapid, which can lead to an excess number of heads opening or having the flame front move faster than the heads can operate. Full-scale fire tests on FRP panels demonstrated five factors that determined their performance:

  1. Backing: The lack of backing on both sides of the panel allowed heat to dissipate and slowed flame spread.
  2. Automatic sprinklers: They slowed horizontal flame spread, lowered ceiling temperatures and provided quick fire extinguishment after the heat is dissipated.
  3. Fire retardants: Though the retardants do not make the panel noncombustible (after all, it is a plastic), they slow down the flame spread and will contribute to stall any burning once the heat is dissipated.
  4. Panel thickness: Thicker panels will delay burner-through, adding to the flame spread.
  5. Reinforcement: Chopped strand or non-woven reinforcement, less then 50% by weight, reduces panel rigidity and allows holes to develop. Conversely, interwoven mats increase rigidity and allow flame spread.

If using FRP panels in building construction, you should use the following guidelines:

Regardless of whether fire retardant additives are provided for the panels, automatic sprinklers should be provided for the area. The sprinkler system should be designed for at least a 0.20-gpm/sq. ft. (8 mm/min.) density over the most remote 2,000 sq. ft. (186 sq. m) area, with a 250 gpm (950 lpm) hose stream allowance, using minimum K5.6, 165°F (74°C) rated heads. Note that the occupancy and other construction demands may be higher than the demand for the panels.

Panels should be unbacked where possible. Even a few feet separate between the panels and the backing will not allow heat to dissipate, allowing fire spread to occur. These panels should be 1/16 in. (1.6 mm) maximum, 8-oz./sq. ft. (2.4 kg/sq. m) maximum, FR treated (ASTM E-84 flame spread of 25 or less), using chopped strand or continuous non-woven reinforcement fiber.

If backing is provided on one side of the panels ensure that it is a thermal barrier (minimum 1/2 in. [13 mm] Type X gypsum board, minimum 1/2 in. [13 mm] ordinary or FR-treated plywood, minimum 26 ga. [0.5 mm] steel or 0.032 in. [0.8 mm] aluminum). Provide a row of quick-response perimeter sprinklers along the top of the ceiling of the unbacked side approximately 2 ft. away from the wall at 10 ft. spacing. The heads should be 1/2 in. (13 mm) minimum, 165°F (74°C) rated. Design this perimeter system for the 10 most heads operating at a minimum 20 gpm (76 lpm) flow per head plus a 250-gpm (950 lpm) hose stream allowance. This design need not be hydraulically balanced with the ceiling design.

If FRP panels are used as part of a sandwich panel system (with an expanded polystyrene, polyurethane or polyisocyanurate core), provide perimeter sprinkler protection as noted above, with the following exceptions:

  • Increase the minimum flow per head to 30 gpm (114 lpm).
  • Hydraulically balance the perimeter system demand with the ceiling demand.

Risk Logic Inc. will evaluate any concerns you may have in using FRP panels with respect to property loss exposure for pre-existing or new construction projects.