Polyiso Insulation: Pros, Cons, and Best Uses
Overview of polyiso insulation — high R-value per inch, fire and moisture resistance, costs, and reduced cold-weather performance for walls and roofs.
Polyisocyanurate (Polyiso) Insulation Explained: Pros, Cons, and Best Uses Polyisocyanurate (Polyiso) insulation is a rigid foam board known for its high thermal resistance (R-value of 6.0–6.5 per inch) and multi-functional performance. It acts as insulation, an air barrier, and a water-resistive barrier when properly installed, making it a top choice for energy-efficient construction. Its lightweight structure, fire resistance, and ability to reduce thermal bridging make it widely used in roofing and wall systems. However, it comes with higher upfront costs and reduced performance in cold temperatures (below 50°F). Proper installation and climate considerations are critical for maximizing its benefits. Key Points: - High R-value: 6.0–6.5 per inch, ideal for thinner walls and roofs. - Fire-resistant: Forms a protective char instead of melting. - Moisture-resistant: 99% closed-cell structure blocks water and air infiltration. - Cost: $1.50–$2.00 per sq. ft. for materials, plus $0.60–$1....