In this episode, our hosts are joined by Tom Harris, a spray foam insulation expert, who discusses the topic of hot roofs and the proper installation of spray foam insulation. He explains the concept of hot roofs, where the thermal boundary is moved to the roof deck, and the different applications and challenges associated with hot roofs. Tom emphasizes the importance of proper installation and the choice of spray foam type based on climate and region. He also discusses the need for thermal barriers and ignition barriers to protect the foam and comply with building codes. Additionally, Tom addresses concerns about shingle warranties and provides insights into foam recommendations for different climate zones. In this conversation, Tom Harris discusses the limitations and capabilities of different insulation materials, including fiberglass and spray foam. He explains how fiberglass insulation can transport air and degrade thermal efficiency, while spray foam acts as an air barrier and doesn't get wet. Tom also discusses the requirements for ignition barriers and fire barriers. He highlights the importance of properly insulating crawl spaces and attics and the benefits of using spray foam in these areas. Finally, he addresses the potential issues of using closed-cell foam directly on the interior of foundation walls without exterior waterproofing or damp-proofing.TakeawaysFiberglass insulation can transport air and degrade thermal efficiency, while spray foam acts as an air barrier and doesn't get wet.Spray foam outperforms its stated R-value by adding concepts of air barrier and moisture control.Ignition barriers and fire barriers are important for safety and code compliance.Proper insulation of crawl spaces and attics is crucial for energy efficiency and comfort.Closed-cell foam is a good option for insulating foundation walls, but exterior waterproofing or damp-proofing is recommended.Chapters00:00 Introduction and Background03:01 Understanding Hot Roofs06:04 Proper Installation of Hot Roofs09:01 Choosing the Right Spray Foam11:58 Protecting Foam with Thermal Barriers20:59 Identifying Thermal Barriers and Ignition Barriers24:57 Foam Recommendations for Different Climate Zones28:04 Importance of Air Leakage Control29:01 Limitations and Capabilities of Insulation Materials32:07 Ignition Barriers and Fire Barriers40:41 Insulating Crawl Spaces and Attics45:37 Insulating Foundation Walls

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