R-Value Table + Assembly Calculation

Insulation Values For Selected Materials

Understanding how different building materials resist the flow of heat is fundamental to designing comfortable and energy-efficient spaces. The R-value quantifies this thermal resistance, with higher values indicating better insulation. The following table provides a comprehensive list of R-values for a wide array of insulation and construction materials, presented both per inch and for common thicknesses. To illustrate how these individual resistances contribute to the overall thermal performance of a building element, an example calculation demonstrates the process of determining the total R-value of a wall assembly by considering the thermal resistance of its various components, including framing members and insulation within the cavity. This approach allows for a detailed assessment of thermal performance and informed material selection in building design.

Use the R-value table below to help you determine the R-value of your wall or ceiling assemblies. To obtain a wall or ceiling assembly R-value you must add the r-values of the individual components together.

Calculating Assembly Wall R-Value

Formula: Assembly R-value = 1 / (Assembly U-value) = 1 / (U-studs x % + U-cavity x %)

Example Component AssemblyR-Value StudsR-Value CavityAssembly R-Value
Wall – Outside Air Film0.170.17 
Siding – Wood Bevel0.800.80 
Container Side Wall Steel Corrugation”0.330.33 
3 1/2″ Fiberglass Batt 11.00 
3 1/2″ Stud4.38  
1/2″ Drywall0.450.45 
Inside Air Film0.680.68 
Percent for 16″ o.c. + Additional studs15%85% 
Total Wall Component R-Values7.1213.73 
Wall Component U-Values0.14040.0728 
Total Wall Assembly R-Value  12.05

* This example is just for wood frame construction. Steel studs are a more complicated calculation

R-Value Table

MaterialR/

Inch
R/

Thickness
Insulation Materials
Fiberglass Batt3.14-4.30 
Fiberglass Blown (attic)2.20-4.30 
Fiberglass Blown (wall)3.70-4.30 
Rock Wool Batt3.14-4.00 
Rock Wool Blown (attic)3.10-4.00 
Rock Wool Blown (wall)3.10-4.00 
Cellulose Blown (attic)3.13 
Cellulose Blown (wall)3.70 
Vermiculite2.13 
Autoclaved Aerated Concrete1.05 
Urea Terpolymer Foam4.48 
Rigid Fiberglass (> 4lb/ft3)4.00 
Expanded Polystyrene (beadboard)4.00 
Extruded Polystyrene5.00 
Polyurethane (foamed-in-place)6.25 
Polyisocyanurate (foil-faced)7.20 
Construction Materials
Concrete Block 4″ 0.80
Concrete Block 8″ 1.11
Concrete Block 12″ 1.28
Brick 4″ common 0.80
Brick 4″ face 0.44
Poured Concrete0.08 
Soft Wood Lumber1.25 
   2″ nominal (1 1/2″) 1.88
   2×4 (3 1/2″) 4.38
   2×6 (5 1/2″) 6.88
Cedar Logs and Lumber1.33 
Sheathing Materials
Plywood1.25 
   1/4″ 0.31
   3/8″ 0.47
   1/2″ 0.63
   5/8″ 0.77
   3/4″ 0.94
Fiberboard2.64 
   1/2″ 1.32
   25/32″ 2.06
Fiberglass (3/4″) 3.00
   (1″) 4.00
   (1 1/2″) 6.00
Extruded Polystyrene (3/4″) 3.75
   (1″) 5.00
   (1 1/2″) 7.50
Foil-faced Polyisocyanurate

   (3/4″)
 5.40
   (1″) 7.20
   (1 1/2″) 10.80
Siding Materials
Hardboard (1/2″) 0.34
Plywood (5/8″) 0.77
   (3/4″) 0.93
Wood Bevel Lapped 0.80
Aluminum, Steel, Vinyl

   (hollow backed)
 0.61
   (w/ 1/2″ Insulating board) 1.80
Brick 4″ 0.44
Interior Finish Materials
Gypsum Board (drywall 1/2″) 0.45
   (5/8″) 0.56
Paneling (3/8″) 0.47
Flooring Materials
Plywood1.25 
   (3/4″) 0.93
Particle Board (underlayment)1.31 
   (5/8″) 0.82
Hardwood Flooring0.91 
   (3/4″) 0.68
Tile, Linoleum 0.05
Carpet (fibrous pad) 2.08
   (rubber pad) 1.23
Roofing Materials
Asphalt Shingles 0.44
Wood Shingles 0.97
Windows
Single Glass 0.91
   w/storm 2.00
Double insulating glass

   (3/16″) air space
 1.61
   (1/4″ air space) 1.69
   (1/2″ air space) 2.04
   (3/4″ air space) 2.38
   (1/2″ w/ Low-E 0.20) 3.13
   (w/ suspended film) 2.77
   (w/ 2 suspended films) 3.85
   (w/ suspended film and low-E) 4.05
Triple insulating glass

   (1/4″ air spaces)
 2.56
   (1/2″ air spaces) 3.23
Addition for tight fitting drapes or shades, or closed blinds 0.29
Doors
Wood Hollow Core Flush 

   (1 3/4″)
 2.17
   Solid Core Flush (1 3/4″) 3.03
   Solid Core Flush (2 1/4″) 3.70
   Panel Door w/ 7/16″ Panels 

   (1 3/4″)
 1.85
Storm Door (wood 50% glass) 1.25
   (metal) 1.00
Metal Insulating 

   (2″ w/ urethane)
 15.00
Air Films
Interior Ceiling 0.61
Interior Wall 0.68
Exterior 0.17
Air Spaces
1/2″ to 4″ approximately 1.00