When the R-value of a material is high the greater the insulating power of the material. Armed with this knowledge you should always buy insulation material according to its R value and not choosing according to thickness. The R-value of all insulation should be printed directly on the material or on the package covering the materials. There are several different types of insulation. Batts are precut in four foot or eight foot lengths.
Blankets are continuous rolls.
Insulation can be made out of fiberglass or rock wool. These are both sold with or without a vapor barrier facing. Loose fill insulation made of rock wool, glass fiber, vermiculite or perlite must always be poured in place by hand. Loose fill made of poly urea foam must be blown into enclosed walls with special equipment. Most rigid insulations are used for interior or exterior sheathing and around a foundation perimeter.