Fire And Flame Resistance of Plywood

There are two ratings applied to buildings with regard to response to fire:

• Fire resistance level. This can apply only to a total building element e.g. a fire door or a wall or roof system. A product cannot be fire rated; and
• Early Fire Hazard Indexes. These are a measure of a product's surface characteristics relating to spread of flame, heat evolved, smoke emission and ignition.

The requirements for fire resistance ratings are incorporated in Australian Standard AS1530 - Part 4 1997 Method for Fire Tests on Building Materials, Components and Other Structures. The early fire hazard requirements are incorporated in AS1530 Part 3 1989.

Early Fire Hazard indices as defined in AS1530 Part 3 for untreated pine plywood are:

• Ignitability index 14,
• Spread of Flame index 8,
• Heat evolved index 7,
• Smoke Developed index 2.

Although the indices are mildly species dependent, these properties can be used almost universally. These indices can be reduced by treatment with fire retardant chemicals should it be required.

Plywood is quite acceptable for use in fire resistance components or structures, provided it is combined with other materials in ways that meet fire resistance requirements. This can be achieved chemically or by combining plywood with non-combustible materials such as fibrous-cement or plasterboard.

Spread of Flame is usually concerned with walls, ceilings, partitions and floors where plywood may be used in considerable quantities. A low Spread of Flame index is desirable. Plywood possesses an index that enables it to be used untreated in most applications. In some areas of multi-residential, commercial and industrial buildings, particularly around exits, corridors, and lift wells, raw plywood will not meet the early fire hazard index requirements of the building codes. A low index can be obtained by use of fire retardant paints, varnishes and coatings. However, these finishes are usually unacceptable under building regulations.

Reference: Plywood Association of Australia

| New Search |

| Projects | Technical Data | Specification | Environment | Education | Research | Glossary |

Timber Research Unit
Department of Architecture
University of Tasmania