DIY – How to Insulate Your Attic



Fall is a great time for DIY projects. Once the weather cools from the summer highs, you can tackle outdoor projects that are labor intensive or heavy lifters without the sweat. It’s also a great time to take on projects that will insulate your home against the coming winter frost. Insulating your attic isn’t sweat intensive outdoor work but you’ll find it much cooler in the attic during the fall rather than when the heat rises to the top of your house during the summer. Also, a well-insulated attic keeps you comfortably warm during the winter.

Safety First

Insulating your attic is considered moderately difficult for a beginner. Not so much because it’s difficult but because there are some hazards that you must be cautious around. Most notably, you must be able to walk only on the attic joists (the support boards for the ceiling), otherwise you risk falling through the ceiling. Also, there are overhead dangers. Both from nails protruding through the roof and the low heights were the roof trusses angle down to the wall. Keep safety in mind by wearing a hard hat and being extra careful where you walk.

Another thing you want to be wary about is the possibility of asbestos insulation in older homes. Some attics have vermiculite insulation, which may contain asbestos. Vermiculite is a lightweight, pea-size, flaky gray mineral. Do not disturb vermiculite insulation unless you have had it tested by an approved lab to be sure that it does not contain asbestos. Contact your local health department for the name of an approved lab.

Deciding on an R Value

You’ve probably heard about R-Values that refer to thermal resistance. The higher the R-value, the greater the insulating effectiveness. The R-value depends on the type of insulation, its thickness, and its density. Almost all attic insulation comes as either loose material or in batts that have a lining the insulation material is glued to. Batts are the easiest for determining the R-value because the value is printed on the liner. You determine the R-value of loose material by measuring the thickness with a tape measure.

  • Loose fiberglass is usually yellow, pink, or white in color. The R-value is 2.5 X the depth in inches (4 inches has an R-value of 10).
  • Loose rock wool is usually gray or near white and may have black specs. The R-value is 2.8 X the depth in inches.
  • Loose cellulose is usually small gray flat pieces or fibers from newsprint. The R-value is 3.7 X the depth in inches.
  • You may also have lightweight granules that are vermiculite or perlite. The R-value is 3.2 X the depth in inches.

Your desired R-value varies depending on the climate you live in. In the hottest climates such as Hawaii, Guam, and Puerto Rico you want a total R-value between R30 to R49. Along the Gulf of Mexico you want R-values between R30 to R60. Inland from the gulf, up into Oklahoma and most of California you want R30 to R60. Kansas, Nebraska, southern Illinois, and southern Indiana call for R38 to R60. North of that it is mostly R49 to R60. To calculate a specific insulation level for your particular location and home type, use the DOE Zip-Code Insulation Program.

Installing Insulation

Basic DIY insulation comes in two choices – loose fill or batt (the common term for blanket insulation). Here is what you need to know about installing each.

Loose fill fiber comes in in bags and is blown in-place to the desired depth and density using special machinery you can rent from a home center or tool rental house. You can pour and spread the fibers manually, but the process is much more labor-intensive and the results won’t be nearly as good. Loose fill is best applied to:

  • Attics with joists that don’t match standard batting sizes. These are usually irregular and nonstandard joist spacing.
  • Attics with a lot of obstacles and barriers that need to be worked around.
  • Attics having existing insulation that has bunched up or become deformed. Areas where loose insulation can more easily penetrate.
  • Low-clearance attics with limited headroom for maneuvering during installation.

You also must be comfortable working with a power blower that you may not be familiar with.

Batts of insulation come in rolls of various thicknesses (R-values) and standard widths. Typically widths of 16 inches or 24 inches that fit between joists or studs in a house’s framing. You only need to roll these out and cut the lengths to fit in between the joists. These work best for:

  • Attics with standard joist spacing, especially those with no existing insulation.
  • Attics with few obstacles to work around.
  • Attics with sufficient headroom for maneuvering during installation.

With that information, grab your tape measure and a flashlight to learn what kind of insulation you already have in the attic and how deep it is. Measure out the square footage you need and you’ll be ready to insulate your attic in about one afternoon so that you stay warm and comfy for years to come.

Please leave a comment about your own DIY projects and experiences or if you have questions/comments about this article.

Author bio: Brian Kline has been investing in real estate for more than 35 years and writing about real estate investing for 10 years. He also draws upon 30 plus years of business experience including 12 years as a manager at Boeing Aircraft Company. Brian currently lives at Lake Cushman, Washington. A vacation destination, a few short miles from a national forest. With the Pacific Ocean a couple of miles in the opposite direction.

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