Blanket: Batt and Roll Insulation

Energy Star

Blanket insulation — the most common and widely available type of insulation — comes in the form of batts or rolls. It consists of flexible fibers, most commonly fiberglass. You also can find batts and rolls made from mineral (rock and slag) wool, plastic fibers, and natural fibers, such as cotton and sheep’s wool. Learn more about these insulation materials.

Batts and rolls are available in widths suited to standard spacing of wall studs, attic trusses or rafters, and floor joists: 2 inch x 4 inch walls can hold R-13 or R-15 batts; 2 inch x 6 inch walls can use R-19 or R-21 products. Continuous rolls can be hand-cut and trimmed to fit. They are available with or without facings. Manufacturers often attach a facing (such as kraft paper, foil-kraft paper, or vinyl) to act as a vapor barrier and/or air barrier. Batts with a special flame-resistant facing are available in various widths for basement walls and other places where the insulation will be left exposed. A facing also helps facilitate fastening during installation.

See the table below for an overview of standard and high-performance (medium-density and high-density) fiberglass blankets and batts characteristics.

Fiberglass Batt Insulation Characteristics

This table is for comparison of fiberglass batts only. Determine actual thickness, R-value, and cost from manufacturer and/or local building supplier.

THICKNESS (INCHES) R-VALUE COST (CENTS/SQ. FT.)
3 1/2 11 12-16
3 5/8 13 15-20
3 1/2 (high density) 15 34-40
6 to 6 1/4 19 27-34
5 1/4 (high density) 21 33-39
8 to 8 1/2 25 37-45
8 (high density) 30 45-49
9 1/2 (standard) 30 39-43
12 38 55-60