How much insulation is enough?
Insulation is measured in R-values. So, the higher the R-value, the better your walls, floors and ceilings will resist the transfer of heat. The amount of insulation you need depends on where you live. The U.S. Department of Energy (DOE) has established thermal (or R-value) recommendations for homes based on geographic zones.
Glass mineral wool residential building insulation products come in R-values ranging from R-8 to R-38 for glass mineral wool batts and rolls. Glass mineral wool blowing insulation can also be blown in an attic to nearly any R-value. You’ll find the R-value of your insulation printed on the package or bag it comes in. R-values are also printed on the facings of glass mineral wool batts and rolls.
No matter what kind of insulation you currently have in your attic, one quick way to determine if you need more is to look across the span of your attic. If your insulation is just level with or below your floor joists (i.e., you can easily see your joists), you should add more. If you cannot see any of the floor joists because the insulation is well above them, you probably have enough and adding more may not be cost-effective. It is important that the insulation be evenly distributed with no low spots; sometimes there is enough insulation in the middle of the attic and very little along the eaves. To see how to add insulation out to the eaves, see Installing Rafter Vents. If your attic insulation covers your joists and is distributed evenly, you probably have enough.
How Much Should I Add?
Insulation levels are specified by R-Value. R-Value is a measure of insulation’s ability to resist heat flow. The higher the R-Value, the better the thermal performance of the insulation. The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.
Add the Right Kind of Insulation
When adding additional insulation, you do not have to use the same type of insulation that currently exists in your attic. You can add loose fill on top of fiberglass batts or blankets, and vice-versa. If you use fiberglass over loose fill, make sure the fiberglass batt has no paper or foil backing; it needs to be “unfaced.” If you choose to add loose fill, we have a blower machine to install it in our Rental Center.
As energy prices continue to rise, it pays to insulate—in more ways than one. Adding more insulation to your home or building can put money in your pocket.
In addition to lower utility bills, according to the EPA, for every $1 homeowners saved on annual fuel bills due to energy-efficient home improvements, their home’s value jumped by $20 or more.
Some local governments and many utility companies offer consumers cash incentives for simply upgrading their insulation. Find out about additional financial incentives in your area.
Lower Mortgage Payments
Planning on financing a new home? Consider an energy-efficient mortgage to help offset added construction costs due to energy improvements. The benefits include:
- Allowing borrowers to qualify for a larger mortgage as a result of energy savings
- Reduced monthly operating costs
- 100% of energy improvements can be financed—up to 15% of the value of the home for existing homes and 5% of the home’s value for new construction