Mixing Cellulose Insulation With Pink Insulation in an Attic

Pink Insulation

• "Pink insulation" is simply fiberglass batt insulation. Fiberglass batts insulation is fabricated from spun strands of glass and plastic polymer that are compressed and fashioned into pre-cut blankets or rolls of insulation from which homeowners cut lengths to fit the attic space. The pink color stems from a marketing ruse by the Owens-Corning company in 1938. It colored its fiberglass pink to make it stand out from the competition, but the color became so well-known that most fiberglass batts are manufactured in pink.

Cellulose Insulation

• Cellulose insulation is predominantly made from recycled newspapers. This material is shredded and combined with fire-resistant chemicals. It is then blown into walls or attic spaces using a pressurized air machine.

Installation

• Before adding the cellulose, check the existing pink insulation for areas of mold or mildew. Cut any affected areas out of the batts. Cover over any vents or wiring and lighting fixtures before you apply the cellulose, so you'll be able to uncover them for regular use after installation. Wear protective clothing and a face mask, as the chemicals in the insulation may irritate the skin and respiratory system. Enlist a partner to keep the hopper of the pressurized-air machine topped up; this will ensure even coverage. Install the insulation evenly in a smooth side-to-side motion.

Vapor Barrier

• Some pink insulation is fitted with a vapor barrier – a foil or paper facing that faces the interior of the attic and prevents moisture from penetrating the fiberglass. If your pink insulation has a facing, remove it before adding the cellulose to prevent moisture from being captured between the layers. Moisture between the layers causes mold and mildew to form. Cellulose insulation is not water resistant, so a homeowner may wish to install a vapor barrier, such as a plastic membrane, over the blown-in insulation, particularly if condensation is an issue in the attic.

Opposite

• The opposite installation, that of fiberglass over cellulose, is not common. Because cellulose is prone to compression, which reduces its effectiveness as a thermal barrier, the addition of fiberglass on top is not recommended. It may be possible to do so if the cellulose has been installed for several years, as it tends to develop a hard crust. However, it is likely to be more effective – and easier in terms of installation – to blow in extra cellulose rather than fit fiberglass batts over existing cellulose.