R-Value Table • 38 Types of Insulation and Roofing • Accurate
(Includes RSI Values)
Roof Online Staff
To learn more about R-value, see Roof Online’s R-Value page.
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Table of Contents
- Related Pages
- About This R-Value Table
- Check with the Manufacturer
- R-Value vs. RSI
- R-Value and Energy Codes
- R-Value Table
- 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 R-value 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 R-value 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. Our R-value table provides typical R-values for the materials listed, but actual products may vary somewhat.
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.
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 R-value table are not for equivalent thicknesses.
Note: Our R-value table provides R-values for roof coverings such as roof shingles and single-ply roof membranes. These R-values are the totals for the typical as-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)
|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)
|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
|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|