Physics > Insulation (R Values)
The term 'R-Value' is used mainly in the building trades to describe the insulating properties of certain materials. The higher the 'R' value, the greater its insulating properties.
A table containing 'R' values of specific materials is included below.
| Material |
R value (ft^2 °F h/Btu) |
| Hardwood siding (1 in. thick) |
0.91 |
| Wood shingles (lapped) |
0.87 |
| Brick (4 in. thick) |
4.00 |
| Concrete block (filled cores) |
1.93 |
| Fiberglass batting (3.5 in. thick) |
10.90 |
| Fiberglass batting (6 in. thick) |
18.80 |
| Fiberglass board (1 in. thick) |
4.35 |
| Cellulose fibre (1 in. thick) |
3.70 |
| Flat glass (0.125 in thick) |
0.89 |
| Insulating glass (0.25 in space) |
1.54 |
| Air space (3.5 in. thick) |
1.01 |
| Free stagnant air layer |
0.17 |
| Drywall (0.5 in. thick) |
0.45 |
| Sheathing (0.5 in. thick) |
1.32 |