Spray Polyurethane Foam (SPF), also known as insulation foam or Spray PU Foam, is a high-performance insulation material. Builders and contractors widely use it in residential, commercial, and industrial buildings because it provides excellent thermal, acoustic, and moisture resistance.
During application, installers spray the polyurethane foam onto a surface, where it rapidly expands to fill cavities. This process creates a seamless, airtight layer that conforms to almost any surface—from smooth walls to uneven roofs and complex building structures.
Types of Spray Polyurethane Foam
SPF is available in two main types — Closed-Cell and Open-Cell — each suited for different applications.
Closed-Cell Polyurethane Foam (CCPF)
Closed-cell foam consists of tiny, gas-filled cells that are completely sealed, making the material dense and rigid.
Key features:
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High R-value: Approximately R-7 to R-8 per inch, offering excellent thermal resistance.
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Moisture barrier: Its impermeability makes it ideal for areas exposed to moisture, such as basements, roofs, and foundations.
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Structural strength: Adds rigidity to walls and roofs; can support weight once cured.
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Density: Around 2 lb/ft³ (32 kg/m³).
Note: Over time, some thermal drift may occur as the trapped gas is replaced by air, mostly within the first two years.
⚠️ Fire Safety Consideration:
Spray foam must be covered with a fire-resistant layer (e.g., ½-inch drywall) in occupied spaces, according to building safety codes.
Open-Cell Polyurethane Foam (OCPF)
Open-cell foam is lighter, softer, and more flexible. Its partially open structure allows air to fill the cells, giving it a spongy texture.
Key features:
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Density: Around 0.5 lb/ft³ (8 kg/m³).
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R-value: Lower than closed-cell, typically R-3.5 to R-4 per inch.
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Sound absorption: Excellent for reducing noise between floors and walls.
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Flexibility: Adjusts to structural expansion and contraction without cracking.
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Breathability: Allows controlled moisture transfer, but should not be used in persistently wet areas.
Installers often select open-cell foam for interior applications where they prioritize flexibility and sound insulation, and where moisture exposure is minimal.
How Spray Polyurethane Foam is Applied
SPF can be applied using spray equipment or single-component cans. Upon application, the chemicals react and expand, forming a durable insulation layer.
Application steps:
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Shake the can thoroughly.
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Attach the correct nozzle (e.g., nozzle A for walls/floors, nozzle B for ceilings).
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Hold the gun at the recommended distance (typically 40–45 cm for walls/floors, 15–20 cm for ceilings).
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Apply in thin layers (maximum 1.5 cm per pass) for optimal performance.
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Apply multiple overlapping layers to achieve desired insulation thickness.
The foam cures quickly and can be trimmed or covered after hardening.
Applications of Spray Polyurethane Foam
Installers can apply SPF to nearly any surface due to its high versatility, including:
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Roofs, attics, and ceilings
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Foundations and basements
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Interior and exterior walls
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Floors and inter-floor spaces
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Balconies, garages, and storage areas
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Vehicle bodies, trailers, boats, and containers
It adheres well to both flat and irregular surfaces, making it suitable for many insulation needs.
Advantages of Spray Polyurethane Foam
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Thermal efficiency: Reduces heating and cooling costs by minimizing heat transfer.
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Acoustic insulation: Absorbs sound to create quieter spaces.
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Water resistance: Once cured, resists moisture and many chemicals.
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Ease of application: Lightweight and does not require adhesives or mechanical fasteners.
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Cost-effective: Minimizes installation time and materials.
Comparison with Other Insulation Materials
| Material | Type | Application Difficulty | Moisture Resistance | Cost | R-Value (per inch) |
|---|---|---|---|---|---|
| Closed-Cell SPF | Spray | Moderate | Excellent | High | R-7 to R-8 |
| Open-Cell SPF | Spray | Moderate | Moderate | Medium | R-3.5 to R-4 |
| EPS/XPS Panels | Sheet | High | Good | Low–Medium | R-4 to R-5 |
| Stone Wool / Glass Wool | Panel/Roll | High | Moderate | Medium | R-3 to R-4 |
Conclusion
Spray Polyurethane Foam is a modern, high-performance insulation solution that combines thermal, acoustic, and moisture protection in one material. With both closed-cell and open-cell options, it can be adapted to almost any application, providing energy efficiency, comfort, and durability for homes, commercial buildings, and vehicles.
Its ease of application, high insulation performance, and versatility make SPF one of the most effective and widely used insulation materials today.
