Types of loose fill attic insulation

Updated February 21, 2017

Loose fill insulation is made up of small particles of material, such as fibreglass or paper. This type of insulation works by trapping air in the spaces between the particles. It's much easier to install than batt or board insulation and can conform to any space. These properties make loose fill insulation an excellent choice for retrofits and for places where other types of insulation are difficult to install. Several different types of loose fill insulation are suitable for attics.


Most cellulose insulation is made from chopped newspaper, treated with fire retardants and has an R-value, or insulation value, of 3.7 per inch, according to Inspectapedia. This material is fluffy, grey to brown and papery in texture. Some cellulose insulation also includes small chips of wood. Cellulose insulation has been used for nearly a century in the U.S. and is considered quite safe as long as the insulation is treated to resist fire. According to Inspectapedia, cellulose insulation is slightly more resistant to mould growth than fibreglass and some other materials.


Fibreglass insulation comes in two forms: the familiar pink batts and a loose fill variety that is blown into walls and attic spaces. Blown fibreglass insulation is pink, yellow, green or white and gets its colour from the resin used to stick the glass fibres together. According to the U.S. Department of Energy, fibreglass insulation is often 20 to 30 per cent recycled glass. This insulation material does pose some respiratory hazards. Airborne fibreglass particles can damage lungs, and fibreglass insulation that's allowed to become wet may grow hazardous mould. According to Inspectapedia, fibreglass insulation has an R-value of 3.14 per inch.

Rock Wool

Rock wool insulation, also called mineral wool and slag wool, is a relatively old material. According to Inspectapedia, rock wool was first developed in the 1850s and patented in the U.S. in 1875. It was commonly used up until the 1950s and still appears in some new construction. According to the U.S. Department of Energy, rock wool insulation contains about 75 per cent recycled material from industrial processes. The material looks cottony but is actually made from mineral fibre. Rock wool is white, grey or brownish. The R-value of rock wool varies. Inspectapedia states that it is as low as 2.25 in loose fill installations or as high as R-4 per inch. Rock Wool insulation is relatively heavy and requires a strong support. Its weight makes it less likely to become airborne than fibreglass, reducing the risk of respiratory damage.

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G.D. Palmer is a freelance writer and illustrator living in Milwaukee, Wis. She has been producing print and Web content for various organizations since 1998 and has been freelancing full-time since 2007. Palmer holds a Bachelor of Arts degree in writing and studio art from Beloit College in Beloit, Wis.