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Insulation

If your family has to bundle up indoors during the winter, it's time to upgrade your insulation - look here to learn why and how.

Find out what R-value means and how it affects the energy efficiency of your home.

 

Insulation is rated by its R-value, which measures its thermal resistance or how well it holds back heat. The higher the R-value, the better.

Bare concrete walls are about R-1, while attic insulation in newly-built Midwestern homes usually measures about R-44.

R-value is proportional to the insulation's thickness, but it also depends on the type of material and its density. The more air pockets an insulating product has, the higher the R-value.

For example, R-38 attic insulation may be 12 inches of fiberglass batts, 10 inches of rock wool loose-fill or seven inches of expanding foam.

 

 

 

 

Type of insulation:

Cellulose

Fiberglass

Rock wool

R-value per inch:

3.2-3.8

2.2-2.7

3.0-3.3

Inches needed for R-38:

10-12

14-17

11.5-3

 

Recommended R-Values

Different areas of your home need different levels of insulation. The list below shows the recommended R-values for homes in the upper Midwest:

  • Attic: R-38 to R-44
  • Sidewalls: R-11 to R-18
  • Basement: R-10 to R-19
  • Crawlspace: R-19

For recommended levels specific to your home and location, try the U.S. Department of Energy’s ZIP-Code Insulation Calculator.

The best place to start is the attic - you'll get the greatest impact by adding insulation here. If you upgrade your attic insulation from three inches to 12 inches, you could save up to 20 percent on your heating costs - and 10 percent on your air conditioning costs!

If you heat your home with electricity, proper attic insulation is even more crucial, because electric heat is costlier and less energy-efficient. The U.S. Department of Energy recommends R-49 attic insulation for homes with electric resistance (baseboard) heating.

Improving sidewall insulation in an existing home is more difficult, but it can help lower your energy costs by up to ten percent. For existing homes, loose-fill insulation can be blown into wall cavities through holes cut under exterior siding.

Or if you're replacing your siding, your contractor can add sheets of rigid foam insulation on top of the sheathing.

Basement and foundation insulation can also lower heating bills by five to ten percent. If you have a crawlspace, insulating the walls in this area can help you save another five percent.

 

Measuring Existing Insulation

Before you head to the home store or call a contractor, you’ll need to measure the amount of existing insulation. To find out, you'll need a flashlight, a ruler, a screwdriver and maybe a ladder.

The first stop is the attic. Measure the depth of the insulation on your attic floor.

To check sidewall insulation, remove the cover plate from an electrical outlet or light switch on an exterior wall [be sure to shut off power at the service panel first], and use the flashlight to check for insulation behind the metal box.

If you can't see behind the box, remove a baseboard in a hidden area, such as a closet - you might see insulation poking out the bottom.

Go to your basement and check the rim joist - the long, thick board that sits on top of the concrete foundation. You might see insulation in the pockets between each floor joist.

If you have a finished basement, remove an outlet cover to check for foundation insulation - here it may be thick foam sheets instead of fiberglass.

 


Types of Insulation

The right insulation material for your home depends on where it will be used and what type you already have. Your contractor or retailer can help you choose the best option for your needs.

 

Fiberglass is the most common type of insulation. It's made from molten glass spun into microfibers.

It's usually pink or yellow and comes in the form of batts or rolled blankets.

Rock wool is literally made from rock - it's manufactured similar to fiberglass, but with molten rock instead of glass.

The gray or brown fibers come in batts or blankets, or as shredded loose-fill.

Cellulose is made from shredded recycled paper, such as newsprint or cardboard.

It's treated with chemicals to make it fire- and insect-resistant, and is applied as loose-fill or wet-sprayed through a machine.

Utility Incentives

Before you make the final decision on whether to upgrade your insulation, be sure to investigate rebates and other incentives from your utility companies on our Utilities Rebate page.