IS 5509:2000 is the Indian Standard (BIS) for fire retardant plywood - specification. This standard specifies the requirements for fire retardant plywood used in building interiors, railway coaches, and other applications. It covers material composition, manufacturing, dimensions, and performance characteristics, particularly focusing on fire resistance tests like flammability and rate of burning.
Specifies the requirements for plywood treated to have fire retardant properties, including test methods and performance criteria.
Key reference values — verify against the current code edition / project specification.
| Reference | Value | Clause |
|---|---|---|
| Performance | Flammability / flame-penetration / surface flame-spread class | Tests |
| Retardant ≠ proof | Delays ignition & flame spread (buys escape time) | Concept |
| Bond grade too | Still specify MR/BWR/BWP — FR ≠ moisture resistance | Critical |
| Class vs NBC | Match flame-spread class to NBC 2016 Part 4 by location | NBC |
| Not | Surface FR paint on normal ply ≠ IS 5509 treated board | Caution |
| Verify | ISI mark + fire-test report (lot-test critical work) | QC |
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
IS 5509:2000 is the specification for fire-retardant plywood — plywood treated so it resists ignition and limits flame spread, for use where the IS 303/IS 710 bond grades alone don't meet fire requirements: panelling, partitions, cladding, duct enclosures and joinery in fire-regulated buildings.
It is read with the timber-product & fire stack:
Fire-retardant plywood is ordinary plywood whose veneers/adhesive/treatment are engineered to delay ignition and slow flame spread — it is *retardant*, not fireproof. IS 5509 fixes:
The key point: FR plywood buys escape time by limiting flame spread — it must be selected against the *NBC flame-spread requirement for that location*, with the correct bond grade for the moisture exposure.
Scenario: wall panelling in an assembly-occupancy corridor (an escape route) with humidity exposure.
Step 1 — fire requirement: read NBC 2016 Part 4 for the surface flame-spread / material class required on an escape-route lining → it mandates a fire-retardant class, not ordinary ply.
Step 2 — specify FR + bond: IS 5509 fire-retardant plywood, *and* the bond grade for the exposure (BWR for humid areas) — state both; FR does not imply moisture resistance.
Step 3 — verify by lot: confirm ISI mark to IS 5509 and obtain the fire-test report; for critical work, lot-test flame-spread/flammability (IS 1734 + IS 5509 fire tests) — surface FR *paint* on normal ply is not acceptable.
Step 4 — detailing: edges/cuts and fixings shouldn't expose untreated core in a way that defeats the rating; finishes must not be a high-flame-spread topcoat over the FR ply.
Step 5 — accept: match the achieved class to the NBC requirement for that location; record certification.
1. Treating FR ply as fireproof. It *retards* — it delays ignition and slows flame spread to buy escape time; it does not make a partition fire-rated (that needs an IS 3614-type tested assembly).
2. FR instead of, not as well as, bond grade. Fire retardancy doesn't confer moisture resistance — a wet-area FR panel still needs BWR/BWP bond; specify both.
3. Surface fire-retardant paint passed off as FR plywood. A coating is not IS 5509 treated plywood and degrades; insist on treated, ISI-marked board.
4. No flame-spread class matched to NBC. 'Fire-retardant' with no class is meaningless — the achieved class must meet the NBC Part 4 requirement for that specific location (escape routes are stricter).
5. Defeating the rating in detailing/finishing. High-flame-spread laminates/paints over FR ply, or exposed untreated cut edges, can negate the benefit.
IS 5509 is reaffirmed; fire-retardant plywood matters wherever NBC Part 4 sets a surface flame-spread / material class — escape routes, assembly/high-rise/critical occupancies — and the recurring failures are conceptual: treating FR ply as fireproof, substituting FR *paint* for treated board, or specifying FR while forgetting the moisture-bond grade. FR plywood's job is narrow and important: slow flame spread to buy escape time, as one element of a fire strategy that also includes compartmentation (IS 3614 doors), detection (IS 2189) and suppression.
The practitioner contract: derive the required flame-spread class from NBC Part 4 by location, specify **IS 5509 FR plywood *plus* the correct bond grade, verify by ISI mark + fire-test report (lot-test for critical work)**, and don't let high-flame-spread finishes or exposed untreated edges defeat it. Genuine, correctly-specified FR ply is a real life-safety contribution; 'FR' as a marketing word on untested or merely surface-coated board is a dangerous illusion.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Surface Flammability Test | Test as per Annex B of IS 5509, which is based on BS 476 Part 7. | Surface spread of flame test using a radiant heat panel. | BS 476-7:1997 |
| Flammability Requirement | Time for flame front to reach 275 mm mark shall not be less than 10 minutes. | For Class 1: Final flame spread must not exceed 165 mm. | BS 476-7:1997 |
| Fire Propagation Index (I) | Shall not exceed 15 when tested as per BS 476 Part 6. | To achieve 'Class 0', the material must be Class 1 (per Part 7) and have I ≤ 12 and i1 ≤ 6. | BS 476-6:1989+A1:2009 |
| Equivalent US Classification | Not specified. Plywood meeting IS 5509 would likely be tested separately. | Class A requires a Flame Spread Index (FSI) of 0-25 and Smoke Developed Index (SDI) < 450. | ASTM E84 |
| Equivalent European Classification | Not specified. | Typically achieves Euroclass B or C, with smoke and droplet classification (e.g., B-s1, d0). | BS EN 13501-1:2018 |
| Durability of Treatment | Must pass flammability test after leaching (72 hours immersion in water at 27±2°C). | Exterior rated FRT wood is often tested after accelerated weathering per ASTM D2898 before E84 testing. | ASTM E84 / D2898 |
| Glue Shear Strength (72h Boil Test) | Specifies minimum average failing loads, e.g., >1000 N for plywood up to 6.5mm thick. | Not specified in fire test standards; defined in plywood product standards like BS EN 636. | BS EN 636 |