How are the required fire-resistance ratings of specific building elements determined?

Fire-resistance ratings are determined by testing a mock-up structural assembly according to procedures in the American Society for Testing and Materials (ASTM) E119 Standard Test Methods for Fire Tests of Building Construction and Materials, available at The test also is known as NFPA 251, Standard …

What is the required fire-resistance rating of the floor construction?

The required rating of the floor construction is specified in Section 414.2. 4, which states that “the floor assembly of the control area and the construction supporting the floor of the control area shall have a fire-resistance rating of not less than 2 hours.”

What is the fire-resistance rating for an interior non bearing wall for Type VA construction?

1 or 602.4. 2 shall be permitted. Interior walls and partitions not less than 1-hour fire-resistance rating or heavy timber complying with Section 2304.11.

What is the fire-resistance rating for interior bearing walls in a heavy timber building?

Interior walls and partitions shall be of solid wood construction formed by not less than two layers of 1-inch (25 mm) matched boards or laminated construction 4 inches (102 mm) thick, or of 1-hour fire-resistance-rated construction.

How is fire-resistance rating calculated?

The fire-resistance rating of a wood frame assembly is equal to the sum of the time assigned to the membrane on the fire-exposed side, the time assigned to the framing members and the time assigned for additional contribution by other protective measures such as insulation.

How do you calculate fire resistance level?

The class and type of construction and the type of building element is used to determine what FRL is required. As an example, a wall between apartments in a 4-storey apartment building will require an FRL of 90/90/90 if it is loadbearing or -/60/60 if it is not.

Which construction type requires a 2 hour fire rating for its floor construction?

Type IV construction utilizes large dimensional lumber for structural members and interior elements. Walls of masonry or other noncombustible walls with a 2 hour fire rating.

What is the difference between Type IIA and IIB construction?

Type IIA has a minimum of 1 hour fire resistance throughout. Type IIB, although noncombustible, has no requirements for fire resistance, unless required by other sections of the code.

What is a 1 hour fire-resistance rating?

A “one-hour” fire rating is given to an assembly consisting of various building materials that can resist the exposure of a standardized fire exposure for one hour.