How to Install Blown-In Attic Insulation

We'll give you general instructions for insulating your home, but always follow the insulation manufacturer's instructions. Here are some things you need to do before you begin:

• Check your local building code for R-value recommendations and any vapor barrier requirements that apply to your area. The R-value of the product indicates how well it insulates.
• Seal gaps that allow unconditioned air into the space you're insulating. Pay attention to areas where plumbing, ductwork or wiring enter the space. See Do-It-Yourself Foam Insulation and How to Caulk for more information.

There are two main types of insulation: batt and roll insulation and loose fill (sometimes known as blown-in insulation):

• Batt and roll insulation works well between joist and stud spaces or if you have a wide-open space or a crawlspace. See Install Batt and Roll Insulation for details.
• Loose fill (blown-in insulation) is best for tight spaces or if your attic already has a layer of insulation that just needs to be topped off. If you choose loose fill insulation, you’ll need to rent a machine to install it.

The type of material you use is up to you. The most important consideration is the insulation’s R-value or its resistance to heat flow. The higher the R-value, the more resistance it has. Your region or your climate will determine the required R-value. Typically, the colder the climate, the higher the R-value you'll need.

• Fiberglass is a common budget-friendly insulation material that reduces your attic insulation cost. It's also fire-resistant.
• Cellulose insulation, which is made from recycled paper that’s treated for fire resistance, packs tightly between the joists.

To determine how much insulation you’re going to need, measure the length times the width of your attic to get the square footage. Then reference the back of the insulation package to determine the proper height to get the right R-value for your project. You can also use our R-Value Insulation Calculator to estimate how much insulation you'll need.

For more information, see our Insulation Buying Guide and our video.

• Wear an old long-sleeved shirt and long pants or even disposable coveralls. Check the insulation instructions for recommended safety gear such as eye protection, gloves and dust masks. If you're working in a crawlspace or attic, you may want to wear knee pads for comfort. A hard hat is also helpful when working in tight spaces, especially around exposed roofing nails.
• A piece of plywood placed over the joists makes a great work surface.
• Open insulation packages carefully and only as you need them. Insulation expands quickly once you open the packaging.
• Don't compress insulation. Compressing the material changes the R-value.
• If you live in an area where frozen pipes are a concern, make sure the insulation protects the pipes from cold air.
• Where necessary, make sure ductwork is insulated to help your heating and cooling system operate more efficiently.