What Is Insulation R Value? Everything You Need To Know (2024)

Table of Contents

  • What Is R-Value?
  • How Much R-Value Should My Insulation Have?
  • How Do R-Values Compare for Types of Insulation?
  • Does a Higher R-Value Help With Tax Credits?

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To a large extent, your home’s insulation is just a matter of comfort. However, that’s not all adequate insulation does. Proper insulation is also a highly effective way to keep your utility bills down, reduce your carbon footprint and improve the resale value of your home.

Whether you are building a new home or remodeling an existing one, taking the time to research ways to improve the insulation is a worthwhile step—and the best place to start is by understanding insulation R-value.

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What Is R-Value?

The R-value for insulation is a way to measure how much resistance the insulation has to heat flow. The higher the R-value, the more the resistance and the better the material is at insulating a home. Generally, insulation materials with higher R-values cost more when compared to those with lower R-values.

For home improvement purposes, R-values range from about R10 for some flooring materials to R60 for dense attic insulation materials.

But, this is where it gets complicated: The assigned insulation R-value represents how much heat resistance the material has per inch of depth. That means a lower R-value material could provide a comparable amount of insulative properties as a higher R-value material if more of it is used.

For example, one inch of insulation with an R-value of R60 is equal to two inches of insulation with an R-value of R30.

How Much R-Value Should My Insulation Have?

In many parts of the country, homeowners can get away with lower R-values for their insulation. Helpfully, the United States Department of Energy has a map that shows the recommended R-value range for different regions of the country. For example, homeowners in parts of the southern United States can insulate their attics with materials that have R-values in the R30 to R60 range and R13 to R19 for floors.

Meanwhile, people living in northern states should use attic insulation with R49 to R60 ratings and floor insulation with R25 to R30 ratings. You may be able to use a material with less R-value if you are adding it to existing insulation.

Although adding insulation to a home isn’t a project at the top of most homeowners’ to-do lists, it’s one that many of us could benefit from: According to the Department of Energy, about nine in 10 homes in the United States are under-insulated. Adding insulation with the right amount of R-value and sealing air leaks around the home can result in 10% savings on annual utility bills.

Also many municipalities will require any insulation that has been exposed during renovation projects to be brought up to code.

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THIS IS AN ADVERTISEMENT AND NOT EDITORIAL CONTENT. Please note that we do receive compensation for any products you buy or sign up to via this advertisement, and that compensation impacts the ranking and placement of any offers listed herein. We do not present information about every offer available. The information and savings numbers depicted above are for demonstration purposes only, and your results may vary.

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How Do R-Values Compare for Types of Insulation?

If you are building a new home, there are a number of decisions to make about the insulation including what’s best for the floors, walls, crawlspaces and the roof. However, for the majority of people looking to improve the insulation in their existing home, the best place to look is upward to the attic. That’s because improving the insulation in the attic is a relatively non-invasive way to help your home retain heat—unlike if you are insulating the walls or flooring, which is often labor intensive.

Additionally, most heat is pulled from the lower floors through the roof; improving attic insulation provides the most bang for your buck in regards to heat loss.

There are several types of roof insulation materials:

  • Loose-fill or blown-in insulation: Low R-value per inch
  • Batt insulation: Low R-value per inch
  • Spray foam insulation: Mid-range R-value per inch
  • Structural insulated panels: High R-value per inch
  • Rigid insulation boards: High R-value per inch

Each type of insulation comes with different pros and cons. For example, structural insulation panels are hard to add to homes and are better to use during the initial construction process. In many cases, adding blown-in, batt or spray foam insulation to existing insulation will be enough to help the space meet the R-value recommendation. However, the Department of Energy warns against compressing insulation by adding denser insulation on top of lighter materials. This will not give you the full R-value rating.

Be careful not to trap kraft-faced paper between layers of batt insulation when adding more fiberglass batt insulation over existing kraft-faced batt insulation. This can trap moisture and create an area for mold to grow. To avoid this, remove the kraft face paper from the existing or first layer of fiberglass batts first, then lay another layer over it.

The Federal Trade Commission requires clear labels about a material’s R-value to be placed on the packaging, which means there shouldn’t be any guesswork on your end. All you need to do is determine the recommended amount of R-value for your geographic location and get the proper kind of insulation for the job.

Does a Higher R-Value Help With Tax Credits?

Effective through December 31, 2021, the federal government offered a tax credit of 10% material costs (up to $500) for the purchase of “typical bulk insulation products” used in an existing home that is your principal residence, and we expect the same for 2022. If you add insulation to your home, save the receipts and you will have to claim the credit using an additional form while submitting your tax return.

In order to get a tax credit, you do not need to buy insulation to a specific R-value. Adding any insulation to an existing home will help with the insulation and should lower your utility bills, too. For that reason, the Department of Energy calls this “one of the most cost-effective home improvement projects you can do.”

What Is Insulation R Value? Everything You Need To Know (2024)

FAQs

What Is Insulation R Value? Everything You Need To Know? ›

The R-value for insulation is a way to measure how much resistance the insulation has to heat flow. The higher the R-value, the more the resistance and the better the material is at insulating a home.

What is considered a good R-value for insulation? ›

Depending on where you live and the part of your home you're insulating (walls, crawlspace, attic, etc.), you'll need a different R-Value. Typical recommendations for exterior walls are R-13 to R-23, while R-30, R-38 and R-49 are common for ceilings and attic spaces.

What is the difference between R13 and R19? ›

R-value is used to judge thermal insulation performance and the higher the number, the better the product's insulating ability. So R19 has better insulating ability than R13. Now R-Value ranges widely across products and home applications. Indeed you will see R60 in some places and R13 in others.

Is R13 or R15 better insulation? ›

R-value is a metric that tells us how well insulation performs at reducing heat loss. When comparing R13 to R15, insulation designated as R15 performs better at reducing heat loss than R13. R-values are generally cumulative, meaning that you can stack two layers of R6 insulation boards to achieve R12.

What is the difference between R19 and R21? ›

R19 is 6.5″ thick whereas R21 is 5.5″ thick. Thinner by one inch and yet 2 points higher in R value. The common explanation as to why this is so, is that the R21 insulation is said to be “more dense”.

Can you have too high of an R-value insulation? ›

The optimal R-value for most homes is 30, but you can go as high as 38 if you live in a tropical climate. Anything higher than 38 indicates an over-insulated space.

What is the thinnest insulation with the best R-value? ›

Thermablok® Aerogel is a revolutionary advancement in thermal technology offering the thinnest insulation available to prevent thermal and cold bridging. Classed as a Super Insulation, Aerogel has the highest insulation value of any known material with the lowest thermal conductivity value of any solid (0.015W/mK).

Can I use R19 in 2x4 walls? ›

Fiberglass and rock wool batts—2x4 walls can hold R-13 or R-15 batts; 2x6 walls can have R-19 or R-21 products.

Can you double up R19 insulation? ›

Two layers of R-19 at 6¼ ” thick will achieve a total R-value of 38. So adding an R-19 batt to an existing R-19 batt will give you a total insulation value of R-38. This is of course assuming that the two batts achieve their label thickness – in this case about 12 inches.

Should I use faced or unfaced insulation? ›

Faced insulation is best for locations prone to moisture, while unfaced insulation is best for dry, interior locations. Unfaced insulation is more sound-proof and cost-friendly. Faced insulation is more fire-resistant and costly. Inspect your insulation annually to make sure it hasn't fallen.

Where to use R13 insulation? ›

What is R13 Batt Insulation? R13 batt insulation is typically used to attenuate sound in interior wall cavities. It is akin to a large blanket, designed specifically to fill a wall, floor, or ceiling cavity.

What is the best insulation for 2x4 walls? ›

Walls built with 2x4s: Use R-13 or R-15 kraft-faced fiberglass insulation or mineral wool insulation when the house's exterior walls are built with 2x4s. Walls built with 2x6s: Use R-19 or R-21 kraft-faced fiberglass insulation or mineral wool insulation when the house's exterior walls are built with 2x6s.

Which insulation thickness should be recommended? ›

TABLE: Average Insulation Thickness Required to Achieve Home R-Value Standards
MaterialR-13R-19
Fiberglass Batt4”5 ¾”
Blown-In3 ¾”5 ½”
Open Cell Foam3 ½”5”
Foam Board2 ½”3 ¼”
1 more row
Feb 19, 2024

How do I choose an R rating insulation? ›

Understanding Insulation R Value

Factors to consider include the climate in your area, the type of building you have, and the specific areas where insulation is needed. For example, homes in colder climates may require insulation with a higher R-value to keep indoor temperatures warm and comfortable.

Can I use R19 in attic? ›

If your attic has little or no existing insulation, you'll want to install an R-38 rated material. If your attic has 2-3″ of existing insulation, you'll want to install an R-30 to achieve a total of R-38. If your attic has 5-6″ of existing insulation, you'll want to install an R-19 to achieve a total of R-38.

Insulation R-Value - InterNACHI®International Association of Certified Home Inspectorshttps://www.nachi.org ›


Insulation R-Value - InterNACHI®

International Association of Certified Home Inspectors
https://www.nachi.org
International Association of Certified Home Inspectors
https://www.nachi.org
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Is R30 insulation good for an attic? ›

In general, however, R30 insulation is a good choice for attics in most climates. It provides a high level of insulation, which can help to keep the attic space cool in summer and warm in winter. R30 insulation is also relatively affordable, making it a budget-friendly option for many homeowners.

What is an acceptable R-value? ›

A R-squared between 0.50 to 0.99 is acceptable in social science research especially when most of the explanatory variables are statistically significant.

What is the highest R-value for a 2x4 wall? ›

Fiberglass and rock wool batts—2x4 walls can hold R-13 or R-15 batts; 2x6 walls can have R-19 or R-21 products. Generally, batt insulation is the least expensive wall insulation material but requires careful installation for effective performance (see page 4).

Can you use R19 insulation in an attic? ›

If your attic has little or no existing insulation, you'll want to install an R-38 rated material. If your attic has 2-3″ of existing insulation, you'll want to install an R-30 to achieve a total of R-38. If your attic has 5-6″ of existing insulation, you'll want to install an R-19 to achieve a total of R-38.

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