The core material defines the panel’s thermal and fire performance.
- XPS (Extruded Polystyrene): Excellent long-term moisture resistance and high compressive strength. Good thermal performance (~R-5 per in). It is a thermoplastic and will melt under intense heat. Common in cold storage and below-grade applications.
- PUR (Polyurethane): Offers the highest R-value per inch (~R-6 to R-7), making it the most thermally efficient. Good adhesion to skins. Standard PUR is combustible.
- PIR (Polyisocyanurate): A chemically modified, upgraded form of PUR. It has a superior fire performance (higher flame and smoke resistance) while retaining very good thermal efficiency (~R-6 per in). PIR is often the preferred choice for commercial buildings due to its better fire rating. Both PUR and PIR are thermosets and will char rather than melt.
