Insulating metal web joists with spray foam insulation can be an effective solution for improving the energy efficiency and comfort of a building. Spray foam insulation provides an air-tight seal, preventing air leakage and heat transfer, and can be applied quickly and easily to metal web joists. Also known as Posi-Joists, this type of structural element is an increasingly popular way to build whilst offering the opportunity to reduce thermal bridging through seamless, monolithic insulation.

In this article, we will discuss the benefits and best practices of insulating metal web joists with spray foam insulation.

Benefits of Spray Foam Insulation for Metal Web Joists

Spray foam insulation provides several benefits for insulating metal web joists, including:

• Improved Energy Efficiency: Spray foam insulation creates an air-tight seal, preventing air leakage and heat transfer, which can significantly improve the energy efficiency of a building.
• Better Comfort: Insulating metal web joists with spray foam insulation can help to maintain a comfortable indoor temperature by preventing heat loss during cold weather and heat gain during hot weather.
• Soundproofing: Spray foam insulation can also help to reduce noise transfer, creating a quieter and more peaceful indoor environment. A low-density open cell spray foam like Sucraseal, can provide excellent sound attenuation.
• Monolithic Sealing: Unlike traditional, pre-cut insulation materials, spray foam insulation can be sprayed between and through the metal web joist for a seamless thermal layer of insulation.

Best Practices for Insulating Metal Web Joists with Spray Foam Insulation

When insulating metal web joists with spray foam insulation, there are some best practices that you should follow:

• Choose the Right Type of Spray Foam Insulation: There are two types of spray foam insulation: open-cell and closed-cell. Open-cell spray foam is less dense and more flexible, making it an excellent choice for irregularly shaped spaces. Closed-cell spray foam is denser and provides a higher R-value per inch, making it ideal for areas with limited space.
• Properly Prepare the Metal Web Joists: The metal web joists should be properly cleaned and free of any debris before applying the spray foam insulation. Any loose rust or debris should be removed, and the surface should be allowed to dry completely before applying the insulation.
• Spray Between the Metal Web Joists: Unlike solid timber joists, metal web joists enable the insulation to pass through the centre which reduces the impacts of thermal bridging. When installing spray foam, ensure the insulation follows between and through the joist for maximum thermal performance.
• Use a Professional Insulation Contractor: Insulating metal web joists with spray foam insulation should be done by a professional insulation contractor who has experience with metal web joists and insulation installation. A professional can ensure that the insulation is installed correctly and meets your needs.

Conclusion

Insulating metal web joists with spray foam insulation can be an effective solution for improving the energy efficiency and comfort of a building. By properly sealing the joists, choosing the right type of spray foam insulation, preparing the metal web joists, and using a professional insulation contractor, you can create an efficient and effective insulation system that will improve the comfort and energy efficiency of your building. 

Current Part L Building Regulations stipulates the requirement to reduce thermal bridging and this is why metal web joists are a great way to build, not only for their enhanced strength but the ability for the insulation to be installed between and through the joist. If you’re considering insulating metal web joists with spray foam insulation, consult with a professional insulation contractor to ensure that the insulation is installed correctly and meets your needs.