Are Fiberglass Stairs Fire Resistant?

Types

• The generic term "fiberglass" refers to either fiber-reinforced plastic or glass-reinforced plastic. Fiberglass is typically made from plastic resin, such as polyester thermo set resin or vinyl resin, combined with glass fibers. While fiberglass generally has high fire-resistance, the specific fire-resistant properties of fiberglass stairs depend on the materials used for the stairs.

Characteristics

• Check with the manufacturer regarding the specific fire-resistant or fire-retardant rating of your product. Polyester resin is fire-retardant to class 1, per American Society for Testing and Materials standard E-84. Vinyl ester resin has the same class 1 rating, per ASTM E-84. Some forms of fiberglass, such as food-grade isophthalic polyester resin, have a lower class 2 fire resistance rating. If fiberglass is not fire-resistant, it will have a rating of NFR or non-fire-retardant.

Rating

• A class 1 rating means the material has a flame spread rating of 25 or less. This is the lowest category. A completely non-flammable material, such as a cement block, has a flame spread rating of zero. To conduct the test, a 20-inch-wide by 25-feet-long section of fiberglass is installed as the ceiling in a gas chamber. One end is then lit on fire, then the distance the flame spreads determines the fire-resistant rating.

Considerations

• Fire-resistant polyester resin, which forms the basis for fire-resistant fiberglass, costs more than fiberglass without fire resistance. However, the extra cost is worth the benefits. To imbue the raw materials with fire resistance, a coreactant compound is combined with the resin during manufacturing. This gives the fiberglass an opaque, white color.