R-Value Table for Insulation and Roofing Materials
(Includes RSI Values)
Roof Online Staff
To learn more about R-value, see Roof Online’s R-Value page.
Table of Contents
Related Pages
- Building Codes and Roofs
- Building Insulation
- Energy Codes and Roofs
- R-Value and Roofs
- Types of Roof Insulation
About This R-Value Table
The following table provides typical R-values (and RSI) for various materials.
These R-values were taken from manufacturer technical data sheets and are the reported R-values per inch of actual products. In a few cases, the R-values we give were taken from a non-manufacturer source that we consider to be trustworthy and accurate.
In all cases, this table is intended only as a general guide to material R-values.
Check with the Manufacturer
When calculating the R-value for a real-life installation, always refer to the manufacturer’s data sheets for the actual, specific product you intend to use, or contact the technical department of the product manufacturer or material provider.
R-Value vs. RSI
R-value is used in the United States. RSI (R-value Système International) is the metric equivalent.
To convert the R-value of a specific thickness of a material to RSI, divide the R-Value by 5.67826. To convert RSI to R-value, multiply the RSI by 5.67826. For example, two inches of extruded polystyrene, with an R-value of 11, has an RSI of 1.93721.
R-Value and Energy Codes
Please note that the R-values for roof membranes, shingles, tiles, air films, and roof deck materials will probably not be permitted by your local code to be included when total roof assembly R-value is being calculated for the purpose of satisfying energy code requirements.
Always check with your local code authority.
R-Value Chart
Note: While the R-Value for a material is typically given per inch, the RSI is typically given per millimeter, so please be aware that the R-Values and RSI values for the materials in the following table are not for equivalent thicknesses.
Note: The R-values given for roof coverings such as shingles or membranes are totals for typical installed thicknesses of those materials. They are not R-values per inch for the material.
| R-Value of Roofing Materials and Building Insulation | ||||
|---|---|---|---|---|
| Material | R-Value per Inch (ft²·°F·hr/BTU) | RSI per Millimeter (K·m²/W) | R-Value for TYPICAL INSTALLED Thickness (NOT per Inch) |
Source |
| Asphalt Shingles | 0.44 | National Roofing Contractors Association | ||
| Built-up Roof Membrane, Gravel-Surfaced (Membrane and Gravel Only) | 0.33 | National Roofing Contractors Association | ||
| Built-up Roof Membrane, Smooth-Surfaced (Membrane Only) | 0.24 | National Roofing Contractors Association | ||
| Cellulose, Blown (Attic) | 3.8 | 0.02638 | Cellulose Insulation Manufacturers Association | |
| Cellulose, Blown (Wall) | 3.8 | 0.02638 | Cellulose Insulation Manufacturers Association | |
| Cellulose, Wet Spray | 3.75 | 0.02598 | International Cellulose Corporation | |
| Concrete, Lightweight Insulating | 0.90 – 1.49 | 0.00630 – 0.01024 | Siplast | |
| Concrete, Structural (140 pcf) | 0.08 | 0.00040 | Siplast | |
| EPDM Roof Membrane, Ballasted (Membrane and Ballast Only) | 0.33 | National Roofing Contractors Association | ||
| EPDM Roof Membrane, Fully-Adhered or Mechanically-Attached (Membrane Only) | 0.24 | National Roofing Contractors Association | ||
| Fiber Cement Shingles | 0.21 | National Roofing Contractors Association | ||
| Fiberglass, Batt | 3.14 – 4.29 | 0.02165 – 0.02992 | Johns Manville | |
| Fiberglass, Blown (Attic) | 2.12 – 4.0 | 0.01457 – 0.02756 | Johns Manville | |
| Fiberglass, Blown (Wall) | 4.0 – 4.3 | 0.02756 – 0.02992 | Johns Manville | |
| Fiberglass, Rigid Board | 4.3 – 4.5 | 0.02992 – 0.03110 | Johns Manville | |
| Gypsum Board | 0.90 – 1.12 | 0.00630 – 0.00787 | United States Gypsum Company; Georgia-Pacific | |
| Metal Roof Panels | No Useful R-Value | National Roofing Contractors Association | ||
| Mineral Wool, Batt | 4.0 – 4.22 | 0.02756 – 0.02913 | Owens Corning | |
| Mineral Wool, Blown (Attic) | 2.95 – 3.39 | 0.02047 – 0.02362 | Owens Corning; American Rockwool Manufacturing | |
| Mineral Wool (Rigid Board) | 3.8 | 0.02638 | Rockwool Group | |
| Modified Bitumen Roof Membrane, Granule-Surfaced (Membrane Only) | 0.15 | National Roofing Contractors Association | ||
| Oriented Strand Board (OSB) | 1.0 – 1.24 | 0.00709 – 0.00866 | Minnesota Sustainable Housing Initiative | |
| Perlite Cover Board | 2.64 | 0.01811 | Johns Manville | |
| Phenolic Foam Board | 6.7 – 7.5 | 0.04646 – 0.05197 | Dow Chemical Company | |
| Plywood | 1.0 – 1.24 | 0.00709 – 0.00866 | Minnesota Sustainable Housing Initiative | |
| Polyiso Insulation (Polyisocyanurate) | 5.0 (NRCA) 5.7 (PIMA) |
0.03465 (NRCA) 0.03937 (PIMA) |
National Roofing Contractors Association; Polyisocyanurate Insulation Manufacturers Association |
|
| Polystyrene, Expanded (EPS) | 3.85 – 4.5 | 0.02677 – 0.03110 | Insulation Technology, Inc.; ACH Foam Technologies | |
| Polystyrene, Extruded (XPS) | 5.0 – 5.5 | 0.03465 – 0.03819 | XPSA (Extruded Polystyrene Foam Association) | |
| PVC Roof Membrane, Fully-Adhered or Mechanically-Attached (Membrane Only) | 0.24 | National Roofing Contractors Association | ||
| Slate Roofing | 0.05 | National Roofing Contractors Association | ||
| Sprayed Polyurethane Foam (Closed Cell)) | 4.9 – 7.1 | 0.03386 – 0.04921 | Icynene, Inc. | |
| Sprayed Polyurethane Foam (Open Cell) | 3.7 – 4.0 | 0.02559 – 0.02756 | Icynene, Inc. | |
| Tile Roofing, Including Batten System and Air Space | 2.95 | Boral Roofing | ||
| TPO Roof Membrane, Fully-Adhered or Mechanically-Attached (Membrane Only) | 0.24 | National Roofing Contractors Association | ||
| Wood Fiberboard | 2.5 | 0.01732 | Blue Ridge Fiberboard, Inc | |
| Wood Shakes and Shingles (Cedar) |
0.94 | National Roofing Contractors Association | ||
| Wood (Typical Hardwood) | 0.7 | 0.00472 | U.S. Department of Energy | |
| Wood (Typical Softwood) | 1.4 | 0.00984 | U.S. Department of Energy | |
