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Difference between insulation roll and batt

Updated July 19, 2017

Batt and roll both refer to fibrous blanket insulation. The only difference between batts and rolls is the size into which each is cut and packaged. There are, however, a number of differences within blanket insulation types. It is available faced -- with various facing materials -- and unfaced. It can be manufactured from fibreglass or recycled cotton fibres, and it comes in numerous thicknesses.

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Fibreglass rolls

Rolls of fibreglass blanket insulation are commonly available in lengths of 11.725 m (39 feet 2 inches), 12 m (40 feet) and 21.15 m (70 feet 6 inches). Nominal widths of 27.5, 37.5 and 57.5 cm (11, 15 and 23 inches) are designed to fit typical centre-to-centre stud spacing.

Fibreglass batts

Nominal pre-cut lengths for fibreglass batts are 117.5, 225 and 235 (47, 90 and 94 inches). Like roll products, widths match stud spacing.

Blown-in blanket

As an alternative to preformed blankets, loose fill fibreglass insulation can be treated with a latex adhesive, misted with water on site and blown into stud wall cavities. Tests show that blown-in-blanket (BIB) systems cover significantly better than batts.


Batts and roll insulation are made in nominal thicknesses of 25 cm to 30 cm (4 inches to 12 inches), with R-values ranging from R-11 to R-38. The density of the material affects the R-value. Higher density products have greater R-values per 2.5 cm (1 inch) than lower density material.

Performance standards

The American Society for Testing and Materials, now ASTM International, has maintained voluntary materials standards for over a century.

Type I insulation covers unfaced blankets. Type II covers blankets faced with a non-reflective vapour retarder on one side. Type III covers blanket insulation faced with a reflective vapour retarder. The full specification describes material performance standards for thermal resistance (R-value), fire characteristics, vapour permeability, and packaging and labelling requirements.

Type II and Type III insulation are required to have the flame spread rating, or a warning that states the facing material is flammable, printed every 2.4 m (8 feet) on the facing.

Cotton fibre blanket

Cotton fibre blanket is a relatively new alternative to mineral fibre insulation. Its primary attraction is that it is made using up to 95 per cent recycled cotton fibres --and it is not a skin irritant as fibreglass can be.

Cotton fibre is available in the same nominal widths as other blanket insulations. Roll length is 9.6 m (32 feet) and batts are cut to 2.4 to 1.2 m (96 and 48 inches). Thickness ranges from 5 to 20 cm (2 to 8 inches) with R-values from R-8 to R-30.

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About the Author

Kathryn Wilson began writing in-house technical documents for the construction industry in 1988. Her published articles cover a broad range of topics, having appeared in "The Construction Specifier," "HorsePlay Magazine" and "Transitions Abroad." Wilson holds a Master of Arts in psychology from Antioch University and certification as a mediator.

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