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High Performance Insulation




Insulation is the best financial investment you can make! Some will say you reach the point of dimishing returns, at which point is is no longer advantageous to add insulation. We do not subscribe to this notion.


No matter how much insulation you install, you only do it once, and pay for it once. That is not the case with energy to heat and cool your home; you continue buying it, and paying for it as long as you live in your home! In addition, the price of energy keeps on rising every day, week, month and year; year after year after year! It doesn't take long to realize that the cost of energy very quickly exceeds the cost of insulating and tightening up your home. After that, you earn returns on your insulating and tightening investment every day, week, month and year as long as you live in your home. And, if and when it comes time to sell your home, it is worth more, will sell more quickly, and you are more likely to get your asking price!


Insulation and tightening up your home is the best financial investment you will ever make!


Where to Start

First, check the insulation in your attic, ceilings, exterior and basement walls, floors, and crawl spaces to see if it meets the minimum levels recommended for your area. Insulation is measured in R-values—the higher the R-value, the better your walls and roof will resist the transfer of heat. DOE recommends minimum ranges of R-values based on local heating and cooling costs and climate conditions in different areas of the nation. The map and chart below show the DOE minimum recommendations for your area. For more customized insulation recommendations, check out theZip Code Insulation Calculator.


Four Basic Types of Insulation

Rolls and batts—or blanketsare flexible products made from mineral fibers, such as fiberglass and rock wool. They are available in widths suited to standard spacings of wall studs and attic or floor joists: 2x4 walls can hold R-13 or R-15 batts; 2x6 walls can have R-19 or R-21 products.


Loose-fill insulation—usually made of cellulose. The blown-in material conforms readily to building cavities and attics. Therefore, loose-fill insulation is well suited for places where it is difficult to install other types of insulation.


Rigid foam insulationfoam insulation typically is more expensive than fiber insulation. But it's very effective in buildings with space limitations and where higher R-values are desired. Foam insulation R-values range from R-4 to R-6.5 per inch of thickness (2.54 cm), which is up to twice the R-value of most other insulating materials of the same thickness.


Spray Foam insulationcan be sprayed into walls, roofs, and other areas, and is the best insulation availablefor a number of reasons.

  1. It has a very high R-value, (up to 6.5 per inch if closed cell foam).
  2. It effectively reduces air infiltration to zero wherever it is used.
  3. It eliminates moisture migrating into walls from the moist air in the home.
  4. It makes it very difficult for moisture to get in from the outside as well.
  5. It makes for a stronger structure.
  6. But it is initially more expensive.  However, the initial cost will quickly gain in value given its other attributes noted above.

Insulation Tips

  • Consider factors such as your climate, building design, and budget when selecting insulation R-values for your home.
  • Use higher density insulation, such as rigid foam boards, in cathedral ceilings and on exterior walls.
  • Ventilation plays a large role in providing moisture control and reducing summer cooling bills. Attic vents can be installed along the entire ceiling cavity to help ensure proper airflow from the soffit to the attic to make a home more comfortable and energy efficient. Check with a qualified contractor.
  • Recessed light fixtures can be a major source of heat loss, but you need tobe careful how close you place insulation next to a fixture unless it is marked IC—designed for direct insulation contact. Check your local building codes for recommendations.Spray foam insulation cannot be sprayed against any recessed lighting fixture, IC or not!SeeLightingfor more about recessed cans.
  • $ Long-Term Savings Tip: One of the most cost-effective ways to make your home more comfortable year-round is to add insulation to your attic.


Adding insulation to the attic is relatively easy and very cost effective. To find out if you have enough attic insulation, measure the thickness of the insulation. If it is less than R-22 (7 inches of fiber glass or rock wool or 6 inches of cellulose), you could probably benefit by adding more. Most U.S. homes should have between R-22 and R-49 insulation in the attic.


If your attic has enough insulation and your home still feels drafty and cold in the winter or too warm in the summer, chances are you need to add insulation to the exterior walls as well. This is a more expensive measure that usually requires a contractor, but it may be worth the cost if you live in a very hot or cold climate.


You may also need to add insulation to your crawl space. Either the walls or the floor above the crawl space should be insulated.

New Construction

For new construction or home additions, R-11 to R-28 insulation is recommended at a minimum for exterior walls depending on location (see map below). To meet this minimum recommendation, most homes and additions constructed with 2 in. x 4 in. walls require a combination of wall cavity insulation, such as batts and insulating sheathing or rigid foam boards. Even better is spray foam insulation as described above. If you live in an area with an insulation recommendation that is greater than R-20, you may want to consider building with 2 in. x 6 in. framing instead of 2 in. x 4 in. framing to allow room for thicker wall cavity insulation—R-19 to R-21.


Today, new products are on the market that provide both insulation and structural support and should be considered for new home construction or additions. Structural insulated panels, known as SIPS, and masonry products like insulating concrete forms are among these. Some homebuilders are even using an old technique borrowed from the pioneers, building walls using straw bales. Check the Consumer's Guide for more information on structural insulation. Radiant barriers (in hot climates), reflective insulation, and foundation insulation should all be considered for new home construction. Check with your contractor for more information about these options.

U.S. Department of Energy Recommended* Total R-Values for New Houses in Eight Climate Zones

Recommended Levels of Insulation

Insulation level are specified by R-Value. R-Value is a measure of insulation’s ability to resist heat traveling through it. The higher the R-Value the better the thermal performance of the insulation. The table below shows what levels of insulation are cost-effective for different climates and locations in the home.

Recommended insulation levels for retrofitting existing wood-framed buildings

US map showing recommended insulation levels for retrofitting existing wood-framed buildings



Add Insulation to AtticFloor
Uninsulated AtticExisting 3–4 Inches of Insulation


R30 to R49

R25 to R30



R30 to R60

R25 to R38

R13 to R19


R30 to R60

R25 to R38

R19 to R25


R38 to R60


R25 to R30

5 to 8

R49 to R60

R38 to R49

R25 to R30

Wall Insulation: Whenever exterior siding is removed on an

Uninsulated wood-frame wall:

  • Drill holes in the sheathing and blow insulation into the empty wall cavity before installing the new siding, and
  • Zones 3–4: Add R5 insulative wall sheathing beneath the new siding
  • Zones 5–8: Add R5 to R6 insulative wall sheathing beneath the new siding.

Insulated wood-frame wall:

  • For Zones 4 to 8: Add R5 insulative sheathing before installing the new siding.



Copyright 2012 Ronald Sauve All Rights Reserved

This page was last modified on April 06, 2012

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