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What Is an R-Value?

If you’re installing insulation, you’ll hear a lot of numbers thrown around, one of them being the R-value. But what is the R-value of insulation? Read on to get the answer from the insulation experts at Gold Star Insulation.

What Is the R-Value of Insulation?

fiberglass batt insulation installationIn a simple answer, the R in R-value stands for resistance and is a basic measurement of an insulation material’s heat resistance.

Heat moves. A properly insulated home should reduce that heat flow, keeping it in during the winter and out during the summer. Reducing the heat flow in your home keeps your energy costs low, so good insulation is a must for every homeowner.

Contact us to install insulation and start living more energy efficiently, or keep reading to learn more about R-value and why it’s important.

How Is Insulation R-Value Calculated?

Let’s start at a base point: Solid wood has an R-value of 1. An R-value is also calculated per inch of width. Therefore, a three-inch-thick board has an R-value of 3. Blown fiberglass installed in the attic has an R-value of 2.2 per inch, so 12 inches of it would give you an R-value of 26.4 in your attic installation project.

What R-Value Is Best for Me?

Don’t be fooled into thinking the higher number makes a type of insulation better for your home overall. The problem with insulators that have a higher R-number is they tend to be more expensive, and some homes in certain climates don’t need as much insulation as others.

For example, folks in Alaska need insulation that will stand against temperatures in the negative digits — not so much a concern here in California. That’s why the Department of Energy developed a system that rates different areas of the United States, giving recommendations on the ideal R-value for their region. Here in Sacramento, we’re in zone 3.


Where to install insulation is the second thing you’ll need to know because different areas of your home require different R-values. The attic needs a higher R-value than the walls because heat naturally rises and escapes through your attic.

After you’ve figured out your zone and where your insulation will go, then you look at your options and types of insulation.

This is a lot of information, but don’t worry — you won’t be doing this on your own. An insulation company can help you with all your needs and explain R-value, the right amount of insulation for your home and more.

For a quick visual of where to insulate in your home, check out our interactive infographic:

where to insulate a house

Choosing Insulation for Your Project

The R-value shouldn’t be the only determining factor when you choose insulation. How old your home is, its location and building materials can all play a part in choosing the right insulation.

Cost and the inhabitants of the home may be another factor in your decision-making. No matter what type of installation you choose, Gold Star Insulation can help. As part of the Installed Building Products Family of Companies, we offer resources and expertise few local companies can match.

Contact us to learn more about our insulation installation services or if you’re ready to install insulation in your Sacramento, CA, home.

Call Us AT(916) 229-8445

Where should you insulate in your home? Check out our interactive infographic:

Products We Install
Energy Audits

Our team can help you save money with a home energy audit and air sealing services.


Our insulation team installs batt and blown-in fiberglass insulation.


Environmentally friendly and effective, cellulose works well in homes and buildings.

Spray Foam

Gold Star Insulation is a leading installer of spray foam insulation in the Sacramento area.

Radiant Barrier

An attic radiant barrier can help keep your home cooler and more comfortable.

Insulation Removal

Gold Star Insulation provides home insulation removal services.

Air Sealing

We are committed to saving you money by sealing your attic—which is the main source of air leaks in the home.

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