The Effect of Blown-In Insulation on Shingles

About Blown-In Insulation

• Blown-in insulation, also called loose-fill insulation, provides a quick and effective way to add insulating materials to walls and attic areas. This type of insulation comes in the form of small pieces of materials that are light in weight and can be easily blown into attic and wall spaces with special equipment. Generally, experienced insulation contractors should be hired to insulate areas with blown-in materials.

Types of Blown-In Insulation

• Blown-in insulation can be made of several different types of material, including fiberglass, cellulose and certain minerals, such as rock slag and rock wool. The cellulose material is made from recycled newsprint. The fiberglass for blown-in insulation is generally made from 20 to 30 percent recycled glass, according to the Department of Energy’s EnergySaver website. The mineral wool is made from 75 percent post-industrial recycled materials. The effectiveness of these materials is stated in R-value -- that is, the measure of a material’s heat resistance. Fiberglass has an R-value of 2.2 to 2.7 per inch of material. Cellulose has an R-value of 3.2 to 3.8 per inch of materials. Rock wool’s R-value is between 3.0 and 3.3 per inch of material.

Installation and Effect on Shingles

• In order to blow in these materials into the spaces of a wall or attic, holes may be drilled into shingles, or the shingles may be removed. The insulating materials are then blown into the interior spaces. Afterward, the holes in the shingles are repaired or replaced and sealed to prevent leaks. Insulation materials blocking airflow below the roof can be a problem.

Problems of Blown-In Insulation Materials

• Installing insulation properly requires consideration of a number of safety and ventilation issues. Insulation should not be installed over electrical boxes or connections. Blown-in insulation is often installed so that it blocks air flow to soffit vents, according to writer Kenton Shepard of the PeakToPrairieInspectionService website. This method can lead to problems with overheating of the roof materials and deterioration of shingles. Installing baffles below the insulation will help to prevent moisture buildup that can affect roofing materials.