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PROBLEMS WITH ATTICS —INSUFFICIENT INSULATION
December 4, 2014
Many older homes will not have as much insulation as is currently recommended. In Central Iowa it is recommended that the attic have above a R38 rating. R-value indicates the resistance to heat transfer. The higher the R-value, the better.
Cause: Inadequate insulation levels are an original construction issue. Placing objects on insulation compresses it reducing its effectiveness because the air is removed. The goal of insulation is to hold pockets of air still.
Implications: The obvious implication of inadequate insulation is heat loss. In areas where snow accumulation and ice dams are an issue, low attic insulation levels promote ice dams.
Strategy: To determine the R-value of the attic insulation, you’ll need to identify the insulation material and check its R-value per inch. You’ll then need to measure the average depth of insulation in the attic. For example, if there are four inches of mineral wool insulation, the R-value will be 13 (3.2 x 4). If the recommended attic insulation level is R-25, we have only roughly half the insulation level that would be ideal. We would recommend making this improvement, although we would not rank it as a priority measure.
Improvement Rather Than Repair: Adding insulation to an attic is an improvement, rather than a repair. The home has survived with the existing insulation level to this point and would continue to be habitable if no improvements were made.
The Risks of More Insulation: Adding insulation improperly can cause problems; Improper ventilation, contact with inappropriate objects such as recessed lights, chimneys, etc. Make sure to install new insulation according to manufactures recommendations. See diagram to the right (image courtesy of CarsonDunlop).