What is the best type of insulation for an attic?

Unfortunately, the easiest insulation to install is sometimes not the most efficient for the job.

Blanket insulation or batts come in a variety of materials, fiberglass, mineral wool, natural fibers or plastic fibers. It comes in a convenient roll and is easy to roll out (mostly) between standard-spaced beams and joists.

But for it to work, it needs to go down without any obstructions. In turn, this is not the case for most attics.

To get into all the nooks and crannies, most attics need a form of blown-in or loose-fill insulation, which can be made of cellulose, fiberglass or even foam.

Cellulose insulation is made from recycled paper that has been treated with boric acid to make it insect and fire-resistant. It’s a dusty job but it gives an R-value of about 3.5 per inch, which is good enough for most homes.

Loose-fill fiberglass is cheaper to install, likely because it gives about an R-value of 2.5 per inch and is not an effective insecticide or pest preventative.


Open-Cell and Closed-Cell Foam Insulation

Spray foam, on the other hand, creates a perfect air-tight seal that is pest resistant when installed correctly.

In addition, spray foam comes in two types: open-cell or closed-cell. It is made up of small bubbles (i.e., cells). Open-cell foam is not full encapsulated and closed-cell is.

It provides an R-value of between 3.6 for open cell and 6.5 per inch for closed-cell.

It’s more expensive and should be installed by a professional. One critique is the off-gassing after installation.

Open-cell insulation is often used for interior walls because it provides sound reduction and is not recommended for outdoor applications. On the other hand, closed-cell insulation is often applied in roofing and crawlspace projects or other outdoor applications, and it can be applied anywhere in the home.


What R-value do I need for my attic?

First, you should know that R-value measures insulation’s resistance to heat flow. The higher the R-value the better.

For Tennessee, the Department of Energy’s recommendation for Tennessee is R38-R60 for attics. With a mean R-value of 49, you would need 14 inches of cellulose 19.6 inches of fiberglass and either 12.5 inches of open-cell foam or 7.5 inches of closed-cell foam.

Insulation can be inexpensive, and the energy savings can quickly make up for the investment. Adding insulation is one of the best steps you can take to achieve long-term savings and efficiency for a lifetime.  Call Roscoe Brown and our team can measure the amount of insulation in your home or business and a free estimate on the project.

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