The plywood maintains structural integrity longer than untreated wood during a fire, and is manufactured to meet ASTM E84 (Class A) or CAN/ULC S102-10 standards.
| Spec | Detail |
|---|---|
| Treatment | Pressure-impregnated with fire-retardant chemicals, then kiln-dried |
| Fire performance | Flame spread index of 25 or less (Class A) |
| Standards | CAN/ULC-S102 · ASTM E84 |
| Thicknesses | 1/2 in · 5/8 in · 3/4 in |
| Panel size | 4 ft × 8 ft |
| Moisture content | Re-dried to 15% or less after treatment |
| Typical use | Interior, protected from weather |
| Applications | Roof sheathing, wall sheathing, partitions, backer panels, commercial interiors |
Need fire retardant lumber for the same job? We also supply fire-retardant-treated dimensional lumber and timber.
Class A is the highest surface-burning rating, with a flame spread index of 0–25. Fire-rated plywood tested to CAN/ULC-S102 or ASTM E84 falls in this class.
No. The plywood slows surface flame spread. A fire-resistance rating (for example, 1-hour) applies to a full wall or floor assembly that has been tested as a system. Always confirm assembly requirements with the designer or code official.
Yes. Panels can be crosscut, ripped and drilled without affecting their fire performance.
Standard fire-retardant plywood is made for interior or protected use. Exterior applications need a product formulated for weathering. Ask our team what's available.
Fire-retardant-treated wood is no more corrosive than untreated wood under normal conditions, and it accepts paint well when dry. Follow the treater's fastener guidance for high-humidity areas.
Each panel carries a stamp from the treater and the certifying agency showing the rating and standard. Inspectors look for it, so keep stamps visible where possible.
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