According to NFPA 101, Life Safety Code, indoor play structures exceeding 10 ft in height or 160 ft² in area must meet specific material requirements. While combustible materials are permitted, they are strictly regulated. Specifically, plastic materials, including foam plastics, are allowed only if they have a peak rate of heat release not exceeding 100 kW when tested in accordance with UL 1975 or ASTM E1537. This performance-based requirement is intended to limit the fuel load and fire growth potential of these materials in an occupied space.

A. Combustible materials are permitted, provided they meet stringent fire performance criteria, such as specific heat release rates or flame spread indices.

B. The required flame spread index for "all other combustible materials" is 25 or less, which corresponds to a Class A (or I) interior finish, not Class II.

C. Wood components are permitted but must be fire-retardant-treated wood to reduce their flammability and contribution to fire growth.

1. NFPA 101®, Life Safety Code®, 2021 Edition. Section 11.4.8, "Play Structures."

11.4.8.2.1: States that play structures can be constructed of combustible materials that comply with subsequent sections.

11.4.8.2.2: "Plastic materials shall be limited to those that have a peak rate of heat release not exceeding 100 kW when tested in accordance with UL 1975... or ASTM E1537..."

11.4.8.2.4: "Wood components shall be fire-retardant–treated wood."

11.4.8.2.5: "All other combustible materials shall have a flame spread index not exceeding 25."

2. NFPA 1®, Fire Code, 2021 Edition. Section 20.1.4.10, "Play Structures."

20.1.4.10.2.2: "Plastic materials shall be limited to those that have a peak rate of heat release not exceeding 100 kW..." (This section mirrors the requirements in NFPA 101).