What is the flame spread rating of plywood?

Tests conducted in 1974 by Underwriters Laboratories showed flame-spread ratings from 75 to 200 for common plywood grades. Variables in the UL tests included species group, glue type, thickness and surface texture. All plywood tested exhibited a flame spread of 200 or less.

What is class C plywood?

C-grade is unsanded and may have several minor defects that will need to be repaired with knots up to 1 1/2-inches across, discoloration and sanding defects. C-grade plywood should be used when appearance is not important, such as for subfloors or garages.

Is plywood a Class C finish?

Lumber, plywood, and other wood-based materials typically fall into Class B or Class C when tested and evaluated in accordance with ASTM E84. Flame spread indices for a range of proprietary wood-based interior finish materials, such as factory-applied over- lay finishes, are available from the manufacturer.

What does Class C fire rating mean?

A Class C or Class 3 fire rating has a flame spread rating between 76 and 200. This rating incorporates building materials like plywood, fiberboard, and hardboard siding panels. It also includes any of the faster burning whole woods.

What’s the flame spread of Class B plywood?

Class B Fire Rated Plywood Class B indicates a material that has a flame spread measuring somewhere between 26 and 75 on the scale. Class C Fire Rated Plywood Wood that has been given a Class C rating has a flame spread number of 76 to 200.

What’s the flame spread of Class A wood?

Inorganic materials like tile and brick also fall under the Class A category. Class B indicates a material that has a flame spread measuring somewhere between 26 and 75 on the scale. Wood that has been given a Class C rating has a flame spread number of 76 to 200.

What kind of wood is best for flame spread?

Lumber, plywood, and other wood-based materials typically fall into Class B or Class C when tested and evaluated in accordance with ASTM E84. If the wood product is homogeneous, flame spread may be consid- ered nearly independent of material thickness at thick- nesses greater than 1/2″.

What kind of fire rating do I need for plywood?

Class A is the most desirable category for fire-rated plywood as it indicates a flame spread index of 25 or less. For fire-retardant wood to be substituted for a noncombustible material, it is required to have a Class A rating. Inorganic materials like tile and brick also fall under the Class A category. Class B Fire Rated Plywood