Description
Typical R-values for common insulation materials are summarized in this table, which also identifies the vapor retarder classification for each insulation.
Insulation Type | R-Value per inch | Air Barrier? | Vapor Retarder Classification * |
|---|---|---|---|
| Fiberglass Batt or Board | 2.5-4 | No | Depends on facing |
| Mineral Wool Rigid Board (Mineral Fiber) | 3-4 | No | Depends on facing |
| Expanded Polystyrene (EPS) | 3.8-4.4 | Yes | Typically Class III (2.6 perm/inch) |
| Extruded Polystyrene (XPS) | 5 | Yes | Typically Class II (1.2 perm/inch) |
| Polyisocyanurate (Polyiso) | Approx. 6 | Yes | Depends on facing, typically Class I |
| Polyurethane Spray Foam (high-density) | Approx. 6 | Yes | Typically Class II (1 perm/inch) |
| * Class I: ≤ 0.1 perm Class II: > 0.1 perm to < 1.0 perm Class III: > 1.0 perm to < 10 perm | |||
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