Review Special plywood

Standards and burning indexes of fire-retardant plywood

Fire-retardant (FR) plywood occupies a special place among a wide variety of construction materials. It is also called fire-resistant, fire rated, fireproof etc. Any wood is vulnerable to high-temperature exposure. However, fire-retardant plywood stands out from the rest, being a high-quality material with unique properties.

Fire-resistant plywood is produced according to the same principle as the Exterior plywood and has all its advantages. FR plywood is manufactured from the veneer of deciduous woods which is glued with phenol-formaldehyde resins. FR plywood acquires its fire-resistant properties due to the use of fire retardants - a special flame-retardant organic additive which is added to reduce the risks associated with fire. Peeled veneer is impregnated with these chemicals before the plywood is glued. As a result, strong, non-toxic plywood, which, along with the excellent water-resistant properties, has the highest level of fire safety, is produced.
The advantages of fire-retardant plywood:
- high strength;
- low flammability;
- slow flame spread;
- minimum smoke generation rate;
- resistance to chemicals;
- easy handling.
Usage of fire-retardant plywood
FR plywood is a general purpose, low flammable material, preventing spread of fire on the surface, having a medium smoke-generating capacity and low toxicity of combustion products. Fireproof plywood is a product of heightened water resistance due to being glued with phenol-formaldehyde resin. The plywood has special resin covering which adds such special characteristics to the material as high biostability and exterior resistance.
When exposed to open flame, fire-retardant plywood will not burn like standard plywood, but it will start to char. As soon as the source of fire is removed, charring will stop immediately. This property makes the building material irreplaceable in many areas of application where it is necessary to ensure good fire safety.
The fireproof panels are mostly used in construction, transport engineering, railway carriages manufacturing, subway cars manufacturing and shipbuilding as well as in other areas where fire rated plywood is applicable.
Standards for fire-retardant plywood
Fire-retardant plywood is produced in accordance with certain technical characteristics, specified in the standard. For example:
- grade: 2/2, 2/4 or 4/4;
- standard length of sheets: 1525, 1830, 2950, 3050 mm;
- standard width: 1525 mm;
- standard thickness varies from 4 to 25 mm.

Fire-resistant plywood can be used within a wide temperature range from -50 °C to +45 °C. If this material is used in a facility, where the parameters will exceed the recommended ones, then there is a risk of phenol emission which is toxic for people.
As for the ignition temperature, combustion starts at 270 °C in the open air, and at 350 - 400 °C in an enclosed space. As soon as the ignition source is eliminated, combustion will stop immediately.