Insulation R-Value: Everything You Need to Know

Every homeowner knows that energy costs are a major expense each month. If you live in a cold climate, your heating costs are high, and if you live where it’s perpetually warm, you’re spending a small fortune on air conditioning. But this isn’t just “the way it is.”

You can get your energy costs under control by upgrading your home’s insulation.

The effectiveness of insulation is measured as the “R-value,” which is why this term is so important when adjusting your home insulation. You’ll want your home’s R-value to meet a certain level to ensure your temperature hovers at a comfortable level year-round.

But what exactly is R-value? In this blog, we’ll explain everything you need to know to not only understand R-value but also make the right choice about how to insulate your home.

What is R-Value?

So, what is r value? If you’ve ever purchased a roll of insulation, the packaging was labeled with the letter R and a number, such as R-13. This is the R-value of that particular insulation. Pretty easy, right? But what is that 13 referring to?

Insulation R value is evaluating the insulating material’s thermal resistance. A higher insulation R-value means that the material is better able to resist the heat transfer through it, thus keeping more heat in or out of your home and decreasing heat loss1—wherever you want it to be based on the time of year and accompanying temperatures.

Your R-value needs vary depending on where you live. For example, if you live in a warmer climate, you will need lower R-values than someone who lives in a colder climate. To help you determine your specific needs, the federal government has created a map that divides the United States into eight zones. Each zone has its own recommended R-value for your home, including values for both an uninsulated attic and standard flooring.2

As you can imagine, the northern part of the country requires a higher R-value for insulation materials than the southernmost states—zone 1 includes the very tip of Florida, Guam, Hawaii, Puerto Rico, and the Virgin Islands, while zone 8 is comprised of several boroughs in Alaska; everything else falls somewhere between these two extremes.

This color-coded map makes it easy to find your zone and your recommended range of acceptable R-values, but beyond that, why does it matter?

How Insulation Works

Now that you know what R-value means, let’s backtrack a little and break down how insulation works. This will help you understand how R-values are calculated and how they affect you and your home through thermal conductivity or a thermal envelope

Heat is transferred in one of three ways:

  • Conduction is how heat or electricity is transmitted through substances.
  • Convection refers to the movement created by hot (less dense) air or liquid rising and cool (more dense) air or liquid dropping.
  • Radiation, or radiant heat, travels in a straight line at the speed of light, usually in the form of waves or particles.

The primary purpose of your home’s existing insulation is to slow the conductive and convective heat flow. However, heat will spread from warmer to cooler points in your house until the temperature is the same everywhere. This includes uninsulated spaces. If your attic, for example, isn’t properly insulated, then you will continually lose heat from the rest of your home as it spreads to warm the relatively cooler attic space.1

In warmer months, the opposite is true. Heat comes into your house from the outside and spreads. Heat gain increases causing the cooler air to fight for space with the hot air. Without the right insulation installation, your cooling system will have to work harder to remove the heat from your home.

Types of Insulation

Along with determining the minimum R-value you need to insulate your home, you also need to choose the right kind of insulation. There are many varieties of insulation to pick from. The right kind of insulation for your needs will depend on where you live, the R-value required, and your home’s features. 

Some of the most commonly used types of insulation are:3

  • Blanket batts and rolls – Made of fiberglass or other material, this type of insulation is ideal for unfinished walls and floors. It’s generally pretty easy to install and is not as expensive as some other kinds of insulation. Fiberglass is also fireproof.
  • Foam board or rigid foam – Foam insulation is more difficult to install and must be covered with a fire-resistant material if used on interior walls. It is made of polystyrene or polyurethane and can be installed on unfinished walls, roofs, and floors.
  • Loose-fill or blown-in – Special equipment is required to install these bits of fiberglass insulation, cellulose insulation, or mineral wool. It can be used to add insulation to hard-to-reach areas. Ceiling insulation and crawl space insulation can benefit from this type of insulation material.

What Parts of the Home Need Insulation?

The short answer is all of them. Your entire home needs to be properly insulated to maximize the efficiency of your heating and cooling systems. Some key areas where energy loss occurs include:4

  • Around windows and doors
  • The home’s roof
  • Insufficiently insulated exterior walls
  • Floors over an uninsulated basement or crawlspace
  • Foundations without barriers between the earth and concrete

If your home is drafty in winter or hot in summer, it’s possible you need to evaluate and improve the insulation in these areas. This is especially true of older homes where the previous efforts to insulate the home may be outdated and inefficient.

How Much Insulation Do I Need?

The recommended R-values for each part of your home will vary depending on the climate where you live and the construction of your house. 

Here are some general guidelines for insulation R-values in key parts of your house. However, it would be wise to check the recommendations for your specific climate and enlist the help of a professional before proceeding with insulating your home.5


The absolute minimum for attic insulation R-values across the country is R-30, with upper recommended ranges between R-49 and R-60 for zones 1 through 3. Zone 4, which includes much of the Pacific Northwest and a middle horizontal slice of the country, has a minimum of R-38 because it’s a bit cooler than its southern counterparts, though still relatively mild. In colder climates—zones 5 through 8—you’ll want at least R-49.2 

Remember that these numbers are simply the minimum recommendation, and you can’t go wrong with higher R-values and a better-insulated space, though it may not be worth the extra cost.

Exterior Walls

The insulation used in your exterior walls is going to be limited by space. Your wall studs are likely 16” apart, so your insulation will need to fit between the studs. Typically, the R-value should be between R-13 and R-23.

Basements & Crawlspaces

Your home’s basement or crawlspace can also be the main culprit if you’re losing energy due to poor insulation. The best space to insulate in a basement or crawlspace is the walls. This will reduce the loss of heat through the home’s foundation. 

The R-value recommendation can range from R-25 in warm to moderate areas to R-49 in very cold climates. A range of R-25 to R-38 is appropriate for most of the country.


If you choose to insulate under your floors, the typical recommendation is:

  • R-25 for cold climates
  • R-19 for mild climates
  • R-13 for warmer climates

One thing to be careful of when insulating floors is the potential to trap moisture. A professional can help ensure that you’re insulating your floors properly.

Why is R-Value Important?

The right level of insulation in your home is critical. Without it, you likely won’t feel truly comfortable nor will you be able to maximize the energy efficiency of your home. But simply insulating your attic or basement isn’t enough if you’re not following the minimum guidelines for the region’s R-values. 

Here are just a few reasons why understanding and implementing the right insulation R-values is so important:

  • Energy efficiency – There’s a reason why the government poured so many resources into establishing recommended R-values for all climates and locations. The more efficient your home is at keeping the heat in or out, the less energy you’ll use to maintain a safe and comfortable temperature. If the entire country uses less energy to heat and cool their homes, there’s less environmental impact in the long run.
  • Cost efficiency – Not only will you save the environment but you’ll also save money on heating and cooling costs. Properly insulating your home will save you an average of 15% on heating and cooling, according to the EPA.6 Demonstrating that your home is energy efficient will also increase the overall market value of your home if and when you decide to sell it.
  • Overall comfort – Your home is likely the biggest investment you’ll ever make. It should be a place you can relax in. You don’t want to be shivering in the winter or sweating in the summer. Investing in the right insulation R-values for your needs will make you more comfortable year-round. 
  • Pest resistance – If you’ve ever had a pest problem in your home, you know that it can escalate quickly. Two mice can become twenty in the blink of an eye. Even small creatures can cause a lot of damage. The right insulation levels can help protect your home from pests such as insects and rodents. These creatures usually sneak in through spots that are not sealed correctly. If your home is fully insulated, this will close off the critters’ entrance point.
  • Longevity – If your home has insulation with the right R-values for your area’s climate, it’ll last longer. This is because the right level of insulation protects not only you but the interior of your home from shifts in temperature. Drywall, flooring, pipes, and ductwork can all warp and sustain damage during extreme temperatures, and repairs on any of these structural components can be very expensive. Maintaining a comfortable indoor climate will prolong the life of your home.

Attic Construction: The Experts You Need

There’s a lot to consider when it comes to insulating your home, but understanding the insulation R-value meaning is one of the most important first steps. Now, you’re well on your way! When it comes to actually implementing insulation upgrades, you’ll want to turn to experts like the technicians at Attic Construction.

Some areas of the country, like California and Arizona, have special considerations for insulation that better protect your home. For help with your home’s insulation or your pressing questions about R-values, Attic Construction is available. We’ll gladly get you set up for a long, happy life in your temperature-controlled home.


  1. Insulation.
  2. Energy Star. Recommended Home Insulation R-Values.
  3. Types of Insulation.
  4. Where to Insulate in a Home.
  5. Today’s Homeowner. Everything You Need to Know About Insulation’s R-Value.
  6. This Old House. How Much Could You Save by Insulating Your Home?

Leave a Comment

Your email address will not be published. Required fields are marked *