Thermal Conductivities (kt) & R values

 

 

Material

kt (in Watts per meter per Kelvin)

 

 

 

Conductors

Aluminum

237

 

Copper

401

 

Gold

318

 

Iron

80.4

 

Lead

353

 

Silver

429

 

Steel

46

 

Diamond

2300

 

 

 

 

 

 

Insulators

Nitrogen

0.0234

 

Air (27oC)

0.026

 

Asbestos

0.08

 

Pine

0.11

 

Helium

0.138

 

Oak

0.15

 

Hydrogen

0.172

 

Concrete

0.19 1.3

 

Rubber

0.2

 

Ice

0.592

 

Water

0.609

 

Glass

0.7 0.9

 

 

 

 

Material

R-value
(ft2 oF hr/BTU)

 

 

Air film

0.17

in. thick drywall

0.45

Flat glass (0.125 in. thick)

0.89

1 in. thick hardwood siding

0.91

3.5 in. dead air space

1.01

Insulating glass (0.25 air gap)

1.54

1 in. thick carpet

2.08

1 in. thick cellulose fiber

3.70

4 in. thick brick

4.00

1 in. expanded polystyrene

4.00

1 in. thick fiberglass batting

4.35

1 in. extruded polystyrene

5.00

1 in. urethane foam

5.75