Your homes insulation works both in the winter and the summer so the amount and type of insulation that you have will make a huge impact on the livability of your home year round. Unfortunately once a home is built it can be difficult to add insulation to the walls but because heat rises and the sun impacts your homes roof increasing attic heat in the summer a large benefit can be seen by increasing the amount of insulation in your attic.
Attic insulation can be installed in either bats which come in 16 or 24 inch width rolls at a fixed height to give a uniform R-Value or it can be loose fill insulation that is blown into the area with a device that kinda resembles a vacuum cleaner set on reverse.
Either type Bat or Loose Fill has its advantages and drawbacks. Bat insulation is somewhat easier for the home owner to install but it can cost more. You are also restricted to predefined R-Value levels. Blown or Loose Fill can be installed by a home owner but is probably left to a professional since it is a pretty messy job. The amount of insulation is only limited by the area available to fill however blown in insulation has a problem with settling and over time the insulation will compact because of its own weight. Some contractors have been known to fluff the insulation or purposely miss spots by building small hills of insulation so a visual inspection of the whole attic is necessary along with a count of the bags as they are dumped into the machine.
Older homes built before 1970 may have little or no insulation in the walls in this instance you can use blown loose fill insulation to fill the voids of the walls by cutting holes to accept the fill hose.
Basement or crawlspace insulation is easy for home owners to install. If you are planning a remodeling project you may want to talk with a contractor about what insulation is best for reducing mold. Walls can be covered with a foam insulation but you must take into account any out gassing of the materials. Some home owners in the 1970’s installed a sprayed Urethane insulation in their basements and even in their walls which was found to emit toxic fumes. The expense of removing the product was almost as much as rebuilding the house. Most foam products are not as dangerous today but for people with health concerns you may want to look at a different product.
We have covered the areas of the home and the different products that you can use to add insulation in areas that are under or not insulated at all. In other HowTos we will cover specific steps for installing these products but what you need to know now is how much of the product you will need to install to see a benefit.
The EPA and Home Building codes set a minimum standard for all areas of our country and specifically state the minimum amount of insulation that should be installed when a home is built. By minimum that means it is always better to exceed the recommendations if you want to save money and have a more comfortable home.
The following table shows the minimum amount of insulation a home should have.
R-Values is the rating of the time that it takes for heat to pass through a substance like insulation. A roll of fiberglass insulation with a higher R-Value will be thicker and will provide more protection from heat or cold.
When Insulation is installed it must not be compressed so if you see a 10inch thick attic insulation bat with a R 20 you can not squish it into a wall cavity that is only 3 inches wide. Compressing insulation actually reduces its effectiveness because it is not the fiberglass its self that does the work it is the air trapped inside it.
Minimum Insulation R-Values for Residential Construction
| Location | Ceiling | Wall | Floor | Basement |
| Warm with cooling and minimal heating requirements (i.e., FL & HI;coastal CA; southeast TX;southern LA, AR, MS, AL & GA) | Gas /Oil R-22 to R-38Electric R-38 to R-49 | Gas / Oil R-11 to R-15 Electric R-11 to R-22 | R-13 to R-25 | Gas / Oil R-11 to R-19Electric R-11 to R-19 |
| Mixed with moderate heating and cooling requirements (i.e.,VA, WV, KY, MO, NE, OK, OR, WA & ID; southern IN, KS, NM & AZ;northern LA, AR, MS, AL & GA; inland CA & western NV). | Gas / Oil R-38 Electric R-49 |
Gas / Oil R-11 to R-15Electric R-11 to R-15 | R13 to R25 | Gas / Oil R-11 to R-19Electric R-11 to R-19 |
| Cold (i.e., PA, NY, New England, northern Midwest, Great Lakes area, mountainous areas (e.g., CO, WY, UT, etc.)). | R-38 to R-49 |
Gas / Oil R-11 to R-15Electric R-11 to R-15 | R25 | Gas / Oil R-11 to R-19Electric R-11 to R-19 |
Information for this table was received from the USA EPA guide: INCREASED INSULATION EPA.gov
The guide above is the minimum and for most homes you should look at installing an R-60 level of insulation in your attic. This is approximately 18 inches of fiberglass insulation and although this may seem excessive it is enough to make a significant difference. Storage areas in the Attic should be reduced to allow for more insulation coverage but if you have a Bonus Room then the attic should have insulation in the rafter areas.
For more information check our other HowTos and our Book Store
Insulate and Weatherize: Expert Advice from Start to Finish
Residential Windows: A Guide to New Technologies and Energy Performance
Popular Mechanics Weatherproofing & Insulation (Popular Mechanics)
Do-It-Yourself Home Insulation (Do-It-Yourself Essentials…)
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