## Common ground
All options are types of insulation boards used for thermal or acoustic insulation in construction.
## Options at a glance
**3921.11 – Cellular polystyrene sheets**
- **Defining trait:** Made from expanded or extruded polystyrene, offering high thermal resistance and rigidity.
- **Typical examples:** XPS (extruded polystyrene) boards for underfloor or wall insulation.
- **Best fit when:** High thermal performance and moisture resistance are needed in dry or buried applications.
**3925.90 – Cellular polystyrene shiplap boards**
- **Defining trait:** Features interlocking shiplap edges for easier installation and tighter joints.
- **Typical examples:** Insulation panels with tongue-and-groove edges for wall or roof systems.
- **Best fit when:** Ease of assembly and reduced air leakage are priorities.
**4410.19 – Insulation board of wood**
- **Defining trait:** Made from solid wood, typically softwood, used in low-density insulation roles.
- **Typical examples:** Wood-based boards for acoustic or thermal use in non-load-bearing walls.
- **Best fit when:** Natural material preference and moderate insulation performance are key.
**4410.90 – Insulation board of other ligneous materials**
- **Defining trait:** Uses non-wood lignocellulosic materials like bamboo, straw, or agricultural waste.
- **Typical examples:** Boards from rice husks or flax fibers for eco-friendly insulation.
- **Best fit when:** Sustainable, renewable raw materials are preferred.
**4411.1X – Insulation board of medium density fibreboard (MDF)**
- **Defining trait:** Manufactured from compressed wood fibers at medium density; good for structural and insulating use.
- **Typical examples:** MDF panels used as both insulation and surface material in partitions.
- **Best fit when:** Combined strength and moderate insulation are needed.
**4411.94 – Wood fiber insulation products (non-MDF)**
- **Defining trait:** Made from compressed wood fibers, often with natural binders; high breathability and eco-friendliness.
- **Typical examples:** Loose-fill or board insulation from recycled wood waste.
- **Best fit when:** Moisture regulation and environmental sustainability are priorities.
**4412.99 – Insulation board made from plywood and wood fiber**
- **Defining trait:** Composite of plywood layers and wood fiber, combining rigidity with insulation.
- **Typical examples:** Structural insulated panels (SIPs) for walls or roofs.
- **Best fit when:** Need both structural integrity and thermal performance.
**4810.3X – Insulation boards of paper or paperboards**
- **Defining trait:** Made from recycled paper or cardboard; lightweight and low-cost.
- **Typical examples:** Paper-based insulation for ceilings or acoustic panels.
- **Best fit when:** Low cost, recyclability, and moderate performance are acceptable.
**6806.90 – Calcium silicate & vermiculite boards**
- **Defining trait:** Inorganic, fire-resistant, and high-temperature stable; often used in industrial settings.
- **Typical examples:** Fireproof insulation for boilers or ducts.
- **Best fit when:** Fire resistance and heat stability are critical.
## Key differences
| HS Code | Material Type | Fire Resistance | Moisture Resistance | Primary Use Case |
|--------|----------------|------------------|----------------------|------------------|
| 3921.11 | Polystyrene | Low | Moderate | General thermal insulation |
| 3925.90 | Polystyrene (shiplap) | Low | Moderate | Wall/roof systems |
| 4410.19 | Solid wood | Medium | Low | Acoustic/thermal, non-structural |
| 4410.90 | Other lignocellulose | Medium | Varies | Eco-friendly alternatives |
| 4411.1X | MDF | Medium | Low | Combined structure & insulation |
| 4411.94 | Wood fiber (non-MDF) | High | High | Sustainable, breathable insulation |
| 4412.99 | Plywood + wood fiber | High | Moderate | Structural insulation panels |
| 4810.3X | Paper/paperboard | Low | Low | Acoustic or low-cost use |
| 6806.90 | Inorganic (calcium silicate, vermiculite) | Very high | High | Industrial/fireproof applications |
## How to choose
- Is the board made from plastic foam? → 3921.11 or 3925.90
- Is it made from wood fibers (not MDF)? → 4411.94
- Does it contain plywood or composite layers? → 4412.99
- Is it inorganic and fire-resistant? → 6806.90
- Is it paper-based? → 4810.3X
## Overlaps & pitfalls
- **Overlap:** MDF (4411.1X) and wood fiber boards (4411.94) both use wood fibers but differ in density and processing.
- **Pitfall:** "Wood" in 4410.19 vs. "wood fiber" in 4411.94 may be confused; the latter is processed, not solid.
- **Priority:** Choose based on **material composition** and **primary function** (e.g., fire resistance > cost)