Determine Current Attic Insulation R-Value

Here Is How To Determine Current Home Attic R-Value

One of the most common questions homeowners ask is how to determine the R-Value of their current attic insulation. This typically results when a homeowner begins to think about improving their home energy efficiency by adding or upgrading the insulation in their attic. And it’s a good place to start. Understanding the current amount of insulation and the R-Value is critical to determining how much is needed to bring the attic to the optimum energy efficiency. Fortunately, for those with blown in cellulose insulation the calculation process is fairly simple and here is the process.

The first step for assessing the current attic insulation is a simple visual check. As a general rule, looking across the attic floor, insulation should be above the top of the floor joists. So if the joists are visible it’s time to consider adding or replacing the insulation.

To understand the current R-Value, an easy way to estimate is by measuring the average depth of the insulation. This chart provides general values for estimating purposes of the most common types of insulation products. Fortunately, for those with blown in cellulose insulation or fiberglass batts the calculation process is fairly simple. Measuring blown in fiberglass is more complicated and really takes specialized equipment and knowledge so best to have an inspection by a qualified insulation contractor.

Chart to Estimate R-Value of Existing Attic Insulation CIMA

Once the current R-Value is estimated, check the recommended R-Value based on the region of the country.

So, for example, a home in Kansas is recommended to have a minimum R38 for attic insulation. With blown-in cellulose insulation, that would require insulation to a depth of 10 inches. If there is already insulation, measure the current depth and subtract to determine the amount needed to bring the attic to the recommended level for the desired R-Value. If this house has 4 inches already, another 6 inches of blown-in cellulose insulation would be needed. Use an insulation savings calculator to get an idea of how much the home would save on energy costs by adding more insulation.

Remember, R-Value is only one of four factors for determining the insulating quality. Learn more about What R-Value really means.

Keep in mind, a home energy audit is recommended when considering energy saving home improvements. Also, a professional insulation contractor is always the best installation option, regardless of the product used, to obtain maximum performance and energy savings. Have more questions, contact CIMA for answers anytime.

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