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INFORMATION BULLETINS
You get what you Inspect, not what you Expect™

R-Values of Common
Building Materials

What's an R-Value? -- this is the unit used to describe thermal resistance. You may have heard of RSI values too. RSI is the metric equivalent of R-values. For example, If in your main attic the standard for insulation of R-40 this would equate to about a RSI value of about 7.1.

R-Values of Common Building Materials

Material R-Value Per Inch R-Value Per Unit
Drywall 0.90 --
Particle Board - Low Density 1.41 --
Particle Board - Medium Density 1.06 --
Particle Board - Low Density 0.85 --
Hardwood 0.90 --
Cement Mortar 0.20 --
Sand & Gravel 0.09 --
Stucco 0.20 --
Masonry Systems R-Value Per Inch R-V Per Unit
Brick - 90 lb/cu.ft. 0.20 --
Brick - 120 lb/cu.ft. 0.11 --
Concrete Block - Normal wt. 8" empty core -- 1.11 - 0.97
Concrete Block - Normal wt. 12" empty core -- 1.23
Concrete Block - Medium wt. 8" empty core -- 1.71 - 1.28
Concrete Block - Light wt. 8" empty core -- 3.20 - 1.90
Concrete Block - Light wt. 12" empty core -- 2.60 - 2.30
Roofing R-Value Per Inch R-V Per Unit
Asphalt roll - 90 lb. -- 0.15
Asphalt shingle -- 0.44
Slate 0.5" -- 0.05
Wood -- 0.94
Asphalt roll - 90 lb. -- 0.15
Siding R-Value Per Inch R-V Per Unit
Wood Shingles 16" - 7" exp. -- 0.87
Wood Drop 1" x 8" -- 0.79
Wood Bevel 3/4" x 10" -- 1.05
Aluminum/Steel - Hollow -- 0.61
Aluminum/Steel - with 3/8" backer -- 1.82
Insulation R-Value Per Inch R-V Per Unit
Blankets/Batts - Fibreglass 3.0 - 3.8 --
Blankets/Batts - Rock Wool 3.0 - 3.8 --
Loose Fill - Cellulose 2.8 - 3.7 --
Loose Fill - Fibreglass 0.7 lb/cu.ft. 2.2 --
Loose Fill - Fibreglass 2.0 lb/cu.ft. 4.0 --
Loose Fill - Rock Wool 3.1 --
Loose Fill - Vermiculite 2.2 --
Rigid Board - Molded Polystyrene 0.9 lb/cu.ft. 3.6 --
Rigid Board - Molded Polystyrene 1.6 lb/cu.ft. 3.6 --
Rigid Board - Extruded Polystyrene 1.9 lb/cu.ft. 5.0 --
Rigid Board - Extruded Polystyrene - Urethanes 5.6 - 6.3 --
Rigid Board - Extruded Polystyrene - Isocyanurate 5.6 - 6.3 --
Sprayed - Cellulose 3.0 - 4.0 --
Foam Filled - Urethane 5.6 - 6.2 --

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