|
| Material | Description |
R-Value per Inch* |
| Fiberglass batts | Pink, yellow, or white; blanketlike | 3.0 |
| Loose-fill fiberglass | Pink, yellow, or white loose fibrous material | 2.5 |
| Loose-fill rock wool | Denser than fiberglass, "wooly," usually gray with black specks (some newer products are white) | 2.8 |
| Loose-fill cellulose | Shredded newspaper, gray, "dusty" | 3.4 |
| Vermiculite | Gray or brown granules | 2.7 |
| Perlite | White or yellow granules | 2.7 |
| Miscellaneous wood products | Sawdust, redwood bark, balsa wood | 1.0 |
| Expanded polystyrene board | Rigid plastic foam board (may be labeled) | 3.8 |
| Extruded polystyrene board | Rigid plastic foam board (may be labeled) | 4.8 |
| Polyisocyanurate board | Rigid plastic foam board (may be labeled) | 5.8 |
| Spray polyurethane foam | Plastic foam, uneven surface | 5.9 |
| Urea formaldehyde foam+ | Whitish gray or yellow, very brittle foam | 4.0 |
| Asbestos++ | May be mixed with other materials; difficult to identify | 1.0 |
* These R-values are for old insulation only. They take into account settling, as well as average R-values for old materials.
+ Urea formaldehyde foam is no longer sold due to concerns about formaldehyde outgassing.
++ If you suspect that you have asbestos, consult a hazardous material specialist before you disturb the insulation.
Sources: PG&E Stockton Training Center, 1993 ASHRAE Handbook of Fundamentals, DOE Insulation Fact Sheet