Typical R-values and Vapor Retarder Classifications for Common Insulation Materials

Description

Typical R-values for common insulation materials are summarized in this table, which also identifies the vapor retarder classification for each insulation.

Table 1. Typical R-Values and Vapor Retarder Classifications for Common Insulation Materials.

Insulation Type

R-Value per inch

(ft2h°/Btu-in)

Air Barrier?

Vapor Retarder

Classification

Class I: ≤ 0.1 perm

Class II: > 0.1 perm to < 1.0 perm

Class III: > 1.0 perm to < 10 perm

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)

 

 

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