What are the main advantages of polyurethane foam insulation, and what are its main drawbacks? What is the cost of installing polyurethane foam insulation? What are the two primary types of polyurethane foam, and how do they differ?
In the U.S., mineral wool (stone and fiberglass) and EPS (expanded polystyrene) foam boards are among the most common insulation materials. However, polyurethane foam insulation is gaining popularity, especially for sloped and flat roofs as well as walls. It’s versatile enough for both residential and commercial buildings, including warehouses and industrial applications.
Cost of Polyurethane Foam Insulation
The cost for polyurethane foam insulation installation generally ranges between $15 and $25 per square meter (approximately $1.40 to $2.30 per square foot), depending on the thickness of the insulation layer, with materials included.
Key Advantages of Polyurethane Foam
One of the biggest advantages of polyurethane foam is the speed of installation. Similar to spray foam (often referred to as “pur foam”), it’s applied by spraying it onto surfaces, where it expands and hardens quickly. The foam typically reaches a thickness of up to 6 inches (15 cm) in two layers. This method allows for the insulation of an entire attic space in less than a day, making it a time-efficient solution compared to other materials.
Transport costs are also lower, as the foam expands on-site, requiring less material to be moved. Another advantage is the foam’s ability to fill complex spaces. For example, when applied to the underside of a roof, it efficiently fills gaps between the boards and rafters, sealing joints where cold spots might otherwise form. This makes it more effective than rigid materials like EPS or stone wool in creating a complete thermal envelope, preventing air leaks and cold bridges.
Two Types of Polyurethane Insulation Foam
Polyurethane foams are classified into two main types: closed-cell and open-cell foams.
- Closed-cell foam contains numerous airtight pockets that trap heat, making it a highly efficient insulator. However, because it blocks moisture as well, it is not suitable for areas with high humidity.
- Open-cell foam is less dense and allows moisture to pass through, reducing the risk of condensation. While this foam has weaker mechanical properties and doesn’t contribute to structural rigidity, its lower insulation capacity means it often requires a thicker application to achieve the same thermal performance as closed-cell foam.
One of the key differences during installation is that open-cell foam requires a vapor-permeable membrane to prevent moisture build-up, whereas closed-cell foam doesn’t need a separate vapor barrier.
Health and Safety Concerns
Polyurethane foam, like EPS, is a synthetic material, unlike stone wool, which is naturally derived. While stone wool is non-combustible, polyurethane foam is initially flammable. However, it is treated with fire retardants during manufacturing to reduce this risk. This has led to concerns about its safety, particularly in residential spaces.
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Although there are no definitive studies proving any health risks from polyurethane foam, the fact that installers must wear protective clothing and masks has raised concerns. Toxic emissions occur only during the drying process and stop within a few hours of the foam setting.
While polyurethane foam offers numerous benefits in terms of installation efficiency and insulating properties, it’s important to consider both the type of foam and the specific requirements of your project.
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