Fire retardant plywood, made to IS:5509
FR grade is treated with fire-retardant chemicals that slow ignition and limit flame spread, and it is made to IS:5509. It sits outside the water-resistance ladder entirely — it is not a wetter or drier version of anything. Where a fire code requires it, no other grade substitutes.
What FR grade actually means
The other four grades are graded by how much water they take. FR is graded by how it behaves in fire, which is a separate property achieved by a separate treatment. A board can be both water-resistant and fire-retardant, but one does not imply the other.
Whether your project requires FR grade depends on building type, occupancy, storey height and the applicable regulations, including the National Building Code and any conditions set by the local fire authority. Confirm the requirement with your architect and fire consultant — not with a supplier, and not with this page.
Where to use it
- Hotels and hospitality interiors
- Hospitals and clinical environments
- Schools and institutional buildings
- Public buildings and assembly spaces
- Larger commercial premises and offices where codes apply
Where it is the wrong choice
- Wet areas, on the strength of the FR label
- FR describes fire behaviour, not water resistance. Specify the water grade separately for the position.
- A private home, by default
- FR is normally specified where a code requires it rather than as a general upgrade.
Specification
| Grade | Fire Retardant Plywood (FR) |
|---|---|
| Indian Standard | IS:5509 |
| Bond | Fire-retardant chemical treatment |
| Thicknesses | 4 mm · 6 mm · 9 mm · 12 mm · 16 mm · 19 mm · 25 mm |
| Sheet sizes | 8 × 4 ft (2440 × 1220 mm) · 7 × 4 ft (2135 × 1220 mm) · 6 × 4 ft (1830 × 1220 mm) |
| Custom sizing | Panels cut to your cutting list for bulk orders |
19 mm is typical for commercial carcasses and partitions; 25 mm for unsupported worktops and counters that get leaned on.
How this board is made
The resin changes with the grade. Nothing else does — every board runs the same seventeen consecutive stations at our line in Hassan, Karnataka, and these four apply to FR grade exactly as they do to every other:
- Composed core
- Core veneers jointed edge-to-edge into full-size sheets before assembly, so the finished board has no internal voids.
- Calibrated thickness
- Both faces ground after pressing so the whole sheet is one uniform thickness — a different operation from sanding.
- ACC preservative treatment
- Dipped in an acid copper chromate bath as a station on the line, so the treatment penetrates rather than coating the surface.
- Laboratory tested
- Samples from every batch tested against IS:303 and IS:710 — moisture content, glue shear strength and water resistance — before dispatch.
Architects and bulk buyers are welcome to walk the line and take a board away to cut open before ordering.
Choosing between the grades
Grade is a water rating, not a quality ranking. The most common and most expensive error is buying up when the room does not need it.
Guides worth reading first
Questions we get asked
What is FR plywood?
Plywood treated with fire-retardant chemicals that slow ignition and limit flame spread, made to IS:5509.
Is fire retardant plywood mandatory?
It depends on building type, occupancy and the applicable fire regulations. Confirm the requirement with your architect, fire consultant and the local authority.
Is FR plywood also waterproof?
Not inherently. Fire behaviour and water resistance are separate properties. Specify the water grade for the position as well.
Tell us the room, the thickness and the quantity and we will quote against it — including when a cheaper grade is the right answer.