Attic Insulation

The primary purpose of attic insulation is to control the environment inside the home to satisfy our comfort needs, reduce operating expenses and to some extent control noise levels.

What are the choices available to accomplish this?


  • Loose Fill or sprayed in place: This is usually cellulose fiber made of recycled newspapers and treated for fire and moisture resistance.

This material generally cost more than fiberglass batts, but is faster and easier to install.

It fills nooks and crannies easily and fits closer to the surrounding joist thus reducing air leakage.

See an example of blown-in attic insulation below.

It can be blown over the ceiling joist to almost any depth and R value. Usually 1 inch will equal an R value of 3 or 4.

A 6 inch joist in reality is only 5.5 inches, therefore the R value will be R16.5 to R22.

The density of the material is the variable. IF you wanted to spray it in to a thickness of 10 inches, the R value could be between 30 and 40.

The drawback is that there is no vapor barrier.

If you are building or remodeling and have access to the ceiling joist before the drywall for the ceiling is installed, simply staple some plastic sheeting to the ceiling before the drywall is installed.

Most big box suppliers will rent you the blower machine to blow in your attic insulation if you purchase the material from them. Check to determine what the minimum purchase requirement is.

This makes the installation process much easier.

This is more often than not a two person job. One feeds the bales into the blower and the other controls the machine via a corded remote or wireless connection.

Hoses are available in 25 foot lengths and can be taped together if needed.

Always be safe, wear a mask and goggles when blowing this material in.

  • Batts and Blankets (Webster’s Dictionary defines a “batt” as “A mass of cotton fibers”): These batts are generally made of fiberglass for attic insulation and come in rolls designed to fit between standard studs, rafters or joist spacing of 16 or 24 inches. The actual batt will be 14 ½ inches wide or 22 ½ inches wide.

The rolls contain either pieces 4 ft long, 8 ft long or uncut continuous rolls.

They will be faced (paper on one side) OR unfaced (no paper). The most common facing is called Kraft facing and it is a vapor barrier to keep condensation at bay.

Make sure the facing you purchase is flame resistant or retardant. The old material used paper with a tar composition that burned. Now it uses fiberglass.

Batts should be installed with the facing pointed toward the living space. Keep gaps and compression to a minimum for maximum efficiency.

The picture below is fiberglass insulation with the facing down so you do not see it in the picture.

The usual rating is R-3 per inch. R-13 is the usual batts used in walls as they expand to 3 ½ inches uncompressed.

Fiberglass batts can be placed in ceiling joist and crossed with additional blankets in the attic. Make sure you purchase the additional blankets are without facing. For good attic insulation make sure to leave NO spaces between the blankets. Do not “pack” the material as it does NOT increase efficiency.

  • Rigid Board Insulation: This material comes in sheets. Colors range from blue to pink to white and almost every variation possible.Thickness ranges from ¼ inch to several inches thick.

    The typical material is polystyrene but could be fiberglass or polyurethane. Some variations come in foil or plastic covered versions.

    This material is great if you want to insulate your metal garage door. Cut the pieces to fit inside the door panels and “pop” the pieces in. I like the plastic covered pieces for this application.

    These panels also have applications in basement walls and inside concrete foundations.

    If you do any gluing make sure the glue you use does NOT eat the material.

  • Spray Foam Insulation: This is a two part liquid that should be professionally installed. I used some of this material in boat once, mixed too much and blew the factory seams apart.This material is applied by mixing two chemicals in the spray gun. It fills cavities with the foaming agent and is waterproof.

    There is an application that is perfect for this material that you can do. This is around pipes, wiring and any place that has openings to the outside. Keep in mind that this material is not UV proof. It usually turns from cream colored to dark brown and flakes off.

    Cover/protect it with some other material to keep it from deteriorating in the sunlight.

Insulation will save you a ton of money if it is properly installed. It also benefits the planet by not wasting energy.

Conservation is the key to the future so use it wisely and save money at the same time.

Dave Altman

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