IS 4990:1993 is the Indian Standard (BIS) for plywood for concrete shuttering work - code of practice. This standard specifies the requirements for plywood intended for use in concrete formwork, commonly known as shuttering plywood. It details the timber species, adhesives (BWP grade), manufacturing process, dimensions, tolerances, and mechanical properties like bending strength and water resistance to ensure durability and reusability.
Provides guidelines for the selection, use, maintenance, and reuse of plywood used as formwork for concrete construction.
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
IS 4990 (1993) is the Code of Practice for Plywood for Concrete Shuttering Work — covering quality, treatment + use of plywood for concrete formwork. Used on millions of concrete pours in Indian construction; cost-effective + reusable shuttering alternative to steel.
Use when: specifying formwork for RCC slabs, beams, columns; large-volume concreting where steel formwork uneconomical; smooth surface finish required.
Material: - Plywood: typically 12-18 mm thick; 9 layers (or per design) - BWP (Boiling Water Proof) grade for severe + repeated use - BWR (Boiling Water Resistant) for moderate use - MR (Moisture Resistant) for interior / dry use - Treatment: pressure-treated phenolic resin - Face: smooth phenolic film for concrete
Sizes: - Standard sheet: 1220 × 2440 mm (8 × 4 ft) - Custom sizes per project - Cuts + edge treatment per requirement
Performance: - Reuse cycles: 8-15 for good quality; up to 25-30 for premium - Surface finish: smooth concrete impression - Density: 600-800 kg/m³ - Specific gravity: 0.55-0.75
Treatment: - Phenolic / film-faced (preferred for re-use) - Polyurethane / acrylic coatings - Edge sealing to prevent moisture ingress
Quality acceptance: - Visual: no delamination, no cracking, smooth face - Bonding: water-boil test (24 hr) - Edge sealing intact - Treatment penetration
Lifespan: - Good quality + handling: 15-25 reuse cycles - Average: 8-12 reuses - Poor handling: 5-8 reuses - Each cycle adds wear; surface deteriorates
Common thicknesses: - 12 mm: small slabs, walls - 15-18 mm: standard slabs + beams - 21-25 mm: heavy loads + spans
Span capability: - 12 mm with 600 mm supports: ~150 mm thick slab - 18 mm with 600 mm supports: ~200 mm thick slab - Heavier with thicker plywood + closer supports
Formwork system: - Plywood face + wood/steel framing + supports - Standard 600 × 600 mm or 600 × 1200 mm panels - Tie rods + form clips - Release agent for clean strip
Stripping time (per IRC:74:1979 + IS 456): - Wall (no load): 12-24 hours - Slab (props left): 7-14 days - Beam sides: 24-48 hours - Slab full release: 14-21 days - Column: 1-2 days
Surface preparation: - Release agent applied before pour - Edges sealed to prevent water absorption - Damaged sections repaired or replaced - Smooth + clean for next pour
Storage: - Stack flat; protected from moisture - Cover or shed storage between uses - Edge protection during transport
Alternatives: - Steel formwork: durable but heavy + expensive - Plastic formwork: lightweight + reusable - Aluminium formwork: high cost; rapid construction - Permanent formwork (PVC / concrete) for specific applications
1. Wrong grade for application (MR plywood for repeated wet use) → delamination. 2. No edge sealing → moisture penetration; warpage. 3. Damaged plywood reused → poor concrete finish + risk. 4. No release agent → concrete sticks; finish damaged. 5. Storage in rain → degradation + warpage. 6. Stripping too early → concrete damage. 7. Stripping too late → unnecessary delay. 8. Quality not certified → defective material. 9. Over-stressing → plywood fails during pour. 10. No supports for spans → sag during concrete pour.
1. Procurement per IS 4990 (BWP / BWR grade). 2. Storage + edge sealing. 3. Formwork system assembly. 4. Release agent application. 5. Concrete pour + cure. 6. Stripping per specification. 7. Cleaning + storage for re-use. 8. Performance monitoring per cycle. 9. Replacement when surface degraded.
IS 4990 is the specification for concrete formwork plywood in India — applied on every concrete project requiring temporary shuttering.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Adhesive Bond Quality Test | Must pass a 72-hour boiling water test without delamination (BWP Grade). | Must pass a 72-hour boiling water test for a Type A bond. | AS 6669:2016 |
| Minimum Modulus of Elasticity (MOE) - Parallel to face grain | 5000 N/mm² | ≥ 7500 N/mm² (for a standard 12mm panel) | JAS 1571:2018 |
| Minimum Modulus of Rupture (MOR) - Parallel to face grain | 30 N/mm² | ≥ 39.0 N/mm² (for a standard 12mm panel) | JAS 1571:2018 |
| Water Absorption (24hr immersion) | Maximum 10% increase in mass. | Not typically specified; thickness swell is the more common metric (e.g., per EN 317). | BS EN 636 / EN 317 |
| Minimum Veneer Thickness (Core) | Not to be less than 1.5 mm (for mechanical peeling). | Not less than 1.5 mm before sanding for Formwork plywood. | AS 6669:2016 |
| Preservative Treatment | Mandatory chemical treatment of all veneers before bonding. | Optional; based on timber species durability and specified in-service hazard level (e.g., H2, H3). | AS 6669:2016 |