All About Insulation R-Values

Insulation ratings are measured in
R-values
per inch of thickness.
An R-value tells you how well a type of insulation can
keep heat from leaving or entering your home. R-value insulation ratings vary based on the type, thickness and density of the insulation material. Typically, a higher R-value
means better climate control and better energy efficiency for your home.
It
usually means a higher price point as well.

For every type and material of insulation, check the R-value per inch of thickness that the manufacturer has listed.
In general, the insulation’s method of installation can give you an idea of how it compares to other types of insulation.

Here are the installation methods from lowest to highest average
R-value per inch:

• Blown-in (or loose-fill) insulation
• Insulation blankets (batts and rolls)
• Spray foam insulation
• Foam board insulation

Note that the material the insulation is made from will change the R-value as well.

Tip: Radiant barriers and vapor barriers are not rated by R-values.

Your home doesn’t necessarily need the highest R-value insulation. The R-value your insulation needs depends on your local climate.

The
map
above
shows
each region of the U.S.
and the
Department of
Energy’s
corresponding climate zone.
Once you find your home’s zone on this map,
you
can
use the below R-value insulation chart to
determine the minimum R-value your insulation should have.

Find your zone on the map and then use the
above insulation R-value
chart to determine the level of insulation you need to properly insulate your attic, walls, floors and crawlspaces.
These R-values are a sum, meaning this should be the total
R-value once you add up the entire depth of insulation. For example, if you have a type of insulation that has an R-value of R-5 per inch of thickness, you will need
a depth of
6-inches
of this insulation installed in
your attic
to reach R-30
if you live in Zones 2 or
3.

Note from this chart that the ideal R-value differs for each part of your home. The ideal attic insulation R-value is different than the ideal wall R-value insulation. Make sure your home is properly insulated in all these locations.

Insulation ratings can be improved by adding more layers of insulation. You can mix the type and material of insulation too. For example, if your attic already has fiberglass insulation blankets installed, you can improve its R-value by installing blown-in cellulose insulation on top of the blankets. The R-values of both insulations will accumulate.
You can achieve better thermal performance in your attic by adding an additional layer of insulation.

As with attics or anywhere else in your home, adding more layers of insulation to your exterior walls is key to having a higher R-value and better thermal performance. Foam board insulation is easy to install between wall studs and over existing blanket insulation.

Spray foam insulation, however, behaves a little differently than other types of insulation. It’s great for sealing gaps around windows and doors because it creates an air seal. Adding more layers won’t increase its performance. Instead, you need to be sure an air seal is created. Spray foam insulation R-value varies, based on manufacturers, which product you choose factors unique to the type of foam. Spray foam insulation R-value is lower for the lighter, open cell foams compared to the denser, closed cell foams. But the R-value can decrease as the foam ages and breaks down, or if the foam gets moisture in its pores.

In addition to attics and exterior walls, you can get greater R-values for your home by remembering to insulate these areas as well:

• Crawlspaces: Next to attics and exterior walls, crawlspaces and basements have the most potential for heat transfer. Be sure that these areas are also adequately insulated.
• Garage: Better temperature control in your garage means you can safely store more items and protect
  your car from overly hot or cold temperatures. Garage insulation is easy to install yourself.
• Water heater and water pipes:
  Adding insulation to your water heater can reduce standby heat losses by 25- to 45-percent, which in turn reduces your energy bills. Wrapping hot water pipes in tubular insulation will also help reduce loss in water heat.
• Ceiling: Enjoy better floor-to-floor climate control in your home by installing ceiling insulation.