Insulation R-Value Chart: R-Values Per Inch (For 51 Materials) - LearnMetrics (2024)

When thinking about insulation, the key metric you have to think about is the insulation R-value. As we have talked about in the post about types of insulations here different materials and types of insulations have different R-values. To help you choose adequate insulation, we have summarized the R-values of 51 most common insulation materials (check the insulation R-value chart below).

The range of R-values of insulation materials spans from materials with R-10 insulation values per inch like vacuum insulated panels and silica aerosol to below R-1 values per inch like bricks, glass, and poured concrete.

Here is the key thing:

When comparing the thermal resistance of insulation materials, you have to compare R-values per inch of thickness. That means that the insulation R-value chart you will find below is basically an insulation thickness chart, based on 1 inch of insulation.

Example: Fiberglass batt has a typical R-value of R-3.7 per inch of thickness. That means that if we were to use 4-inch fiberglass batts, the overall R-value would be R-14.8.

Insulation R-Value Chart: R-Values Per Inch (For 51 Materials) - LearnMetrics (1)

To help you out determine what is the R-value of insulation materials with thickness over 1 inch, we have included R-values for:

  • 2-inch thickness. Example: Closed-cell spray foam has a typical R-value of R-6 per inch. That means that 2-inch closed-cell spray foam has an insulation R-value of R-12.
  • 4-inch thickness. Example: High-density EPS has a typical R-value of R-4.2 per inch. That means that 4-inch EPS has an insulation R-value of R-16.8.
  • 8-inch thickness. Example: Phenolic rigid panel has a typical R-value of R-4.5 per inch. That means that an 8-inch phenolic rigid panel has an insulation R-value of R-38.

You can find all of these insulation R-values per inch and per 2, 4, and 8 inches in the following insulation R-value chart:

Note: Below the table, we address some of the key questions regarding these insulation R-values like what is the best R-value, . You can also use the comment section if you don’t find your answer and we will try to help you out.

Table of Contents

Insulation R-Value Chart (Per 1, 2, 4, 8 Inches Thickness)

Insulation Material:R-Value Per Inch:2 Inch R-Value:4 Inch R-Value:8 Inch R-Value:
Vacuum Insulated Panel (VIP)R-25 Per InchR-50R-100R-200
Silica AerosolR-10.3 Per InchR-20.6R-41.2R-82.4
Polyurethane Rigid Panel (CFC/HCFC Expanded) NewR-7.5 Per InchR-15R-30R-60
Polyurethane Rigid Panel (CFC/HCFC Expanded) After 5-10 YearsR-6.25 Per InchR-12.5R-25R-50
Polyurethane Rigid Panel (Pentane Expanded) NewR-6.8 Per InchR-13.6R-27.2R-54.4
Polyurethane Rigid Panel (Pentane Expanded) After 5-10 YearsR-5.5 Per InchR-11R-22R-44
Foil-Faced Polyisocyanurate Rigid Panel (Pentane Expanded) NewR-6.8 Per InchR-13.6R-27.2R-54.4
Foil-Faced Polyisocyanurate Rigid Panel (Pentane Expanded) After 5-10 YearsR-5.5 Per InchR-11R-22R-44
Closed-Cell Polyurethane Spray FoamR-6 Per InchR-12R-24R-48
Urea FoamR-5.25 Per InchR-10.5R-21R-42
Urea-Formaldehyde PanelsR-5.5 Per InchR-11R-22R-44
High-Density XPSR-5.2 Per InchR-10.4R-20.8R-41.6
Low-Density XPSR-4.15 Per InchR-8.3R-16.6R-33.2
Polystyrene BoardR-5 Per InchR-10R-20R-40
Phenolic Spray FoamR-5.9 Per InchR-11.8R-23.6R-47.2
Polyisocyanurate Spray FoamR-6.3 Per InchR-12.6R-25.2R-50.4
High-Density EPSR-4.2 Per InchR-8.4R-16.8R-33.6
Low-Density EPSR-3.85 Per InchR-7.7R-15.4R-30.8
Phenolic Rigid PanelR-4.5 Per InchR-9R-18R-38
Urea-Formaldehyde FoamR-4.3 Per InchR-8.6R-17.2R-34.4
Icynene Loose-FillR-4 Per InchR-8R-16R-32
Home FoamR-3.9 Per InchR-7.8R-15.6R-31.2
Cotton BattsR-3.7 Per InchR-7.4R-14.8R-29.6
High-Density Fiberglass BattsR-4.3 Per InchR-8.6R-17.2R-34.4
Icynene SprayR-3.6 Per InchR-7.2R-14.4R-28.8
Open-Cell Polyurethane Spray FoamR-3.6 Per InchR-7.2R-14.4R-28.8
Fiberglass BattsR-3.7 Per InchR-7.4R-14.8R-29.6
Rice HullsR-3 Per InchR-6R-12R-24
CardboardR-3.5 Per InchR-7R-14R-28
Wool BattsR-3.4 Per InchR-6.8R-13.6R-27.2
Loose-Fill CelluloseR-3.4 Per InchR-6.8R-13.6R-27.2
Wet-Spray CelluloseR-3.4 Per InchR-6.8R-13.6R-27.2
Polyethylene FoamR-3 Per InchR-6R-12R-24
Loose-Fill PerliteR-2.7 Per InchR-5.4R-10.8R-21.6
PapercreteR-2.9 Per InchR-5.8R-11.6R-23.2
Loose-Fill WoolR-3.1 Per InchR-6.2R-12.4R-24.8
Loose-Fill FibergrassR-3.1 Per InchR-6.2R-12.4R-24.8
Wood Panels (Sheathing)R-2.5 Per InchR-5R-10R-20
Rigid Panel FiberglassR-2.5 Per InchR-5R-10R-20
Loose-Fill VermiculiteR-2.25 Per InchR-4.5R-9R-18
VermiculiteR-2.13 Per InchR-4.26R-8.52R-17.04
Cementitious FoamR-3 Per InchR-6R-12R-24
Thinsulate Clothing InsulationR-2.35 Per InchR-4.7R-9.4R-18.8
Straw BaleR-1.45 Per InchR-2.9R-5.8R-11.6
SoftwoodR-1.41 Per InchR-2.82R-5.64R-11.28
Loose-Fill Wood (Wood Chips)R-1 Per InchR-2R-4R-8
Cellular ConcreteR-1 Per InchR-2R-4R-8
DrywallR-0.9 Per InchR-1.8R-3.6R-7.2
HardwoodR-0.71 Per InchR-1.42R-2.84R-5.68
Sheep Wool BattsR-3.7 Per InchR-7.4R-14.8R-29.6
GlassR-0.14 Per InchR-0.28R-0.56R-1.12
BrickR-0.2 Per InchR-0.4R-0.8R-1.6
Poured ConcreteR-0.08 Per InchR-0.16R-0.32R-0.64
Soft Low-e Double Glazed Insulated GlassR-5.11 Per InchR-10.22R-20.44R-40.88
Hard Low-e Double Glazed Insulated GlassR-3.8 Per InchR-7.6R-15.2R-30.4
Double Glazed Insulated GlassR-2 Per InchR-4R-8R-16
Triple Glazed Insulated GlassR-3.8 Per InchR-7.6R-15.2R-30.4
Uninsulated Glass PaneR-0.91 Per InchR-1.82R-3.64R-7.28

This R-value thickness table is pretty easy to use. You just check which material you want to use, read off the R-value, and compare the R-value of your material with other materials.

Here is a chart that illustrates graphically the differences between R-values for different insulation materials:

Insulation R-Value Chart: R-Values Per Inch (For 51 Materials) - LearnMetrics (2)

Let’s address some of the questions we usually get when advising about insulation materials and their R-values:

Is A Higher R-Value Better For Insulation?

This goes without saying; higher R-values are better for insulation. The relationship between R-value and insulation is positive and linear.

Example: An R-10 insulation is twice as effective as R-5 insulation.

The higher the R-value insulation you use, the less you will spend on heating (in the winter) and cooling (in the summer).

What Is The Best R-Value For Insulation?

Same logic here; the higher the R-value, the better the insulation. The best R-value for insulation is as high as possible. Obviously, you will have to find a compromise between the R-value, the thickness of walls, ceilings, floors, roof, how much can you spend on insulation, and so on.

We can talk a bit about benchmarks about what is a good r value for insulation:

  • Exterior walls should have an R-value ranging from R-13 to R-23. A good R-value for exterior walls is R-23.
  • Attics can have R-30, R-38, or R-49. The best R-value for attics is R-49, or even higher. Is R30 insulation good for the attic? Well, it is about average; R-49 is better for the attic.
  • Ceilings can also have R-30, R-38, or R-49. If you can get a ceiling R-value of R-49, that is a good R-value.

As you can see, it makes sense to have high (R-40 or more) insulation values for places over your head (attics, ceilings). That’s where the hot air usually deprives your house of heat in the winter (increasing the cost of heating), and that is where the sun is shining in the summer, increasing the cost of air conditioning.

What Insulation Has The Highest R-Value?

In three words: Vacuum insulated panels (VIPs). These panels have, according to Wikipedia, ‘about five times the thermal resistance (R-value) per unit thickness’.

As you can see from the insulation R-value chart above, vacuum insulated panels have a typical R-value of R-25 per inch of thickness. Some VIPs can have R-value as high as R-45 or even R-50 per inch. This is an insulation material with the highest R-value altogether.

What Insulation Is Best For Exterior Walls?

A good exterior wall R-value is R-23. To achieve that, you can use any of these exterior wall insulation materials:

  • Fiberglass.
  • Foam boards.
  • Cellulose-based insulation.
  • Batt insulation.
  • Closed-cell or open-cell spray foam. Closed-cell spray foam is better for exterior walls because it is water-resistant, has a higher R-value per inch of thickness than open-cell type, but is also costlier.
Insulation R-Value Chart: R-Values Per Inch (For 51 Materials) - LearnMetrics (3)

What Is The Highest R-Value For A 2×4 Wall?

A 2×4 wall can hold either R-13 or R-15 fiberglass batts. So, if you were to use batt insulation, the highest R-value for a 2×4 wall is R-15.

This means that you are using a 4-inch batt with an average R-value of R-3.75 per inch of thickness.

Some people also ask if you can put R19 in 2×4 walls. Sadly, batts don’t have sufficient R-value per inch to accommodate for R-19 2×4 walls.

What Is The Highest R-Value For A 2×6 Wall?

A 2×6 wall can hold either R-13, R-15, R-19, or R-21 fiberglass batts. So, if you were to use batt insulation, the highest R-value for a 2×6 wall is R-21.

This means that you are using a 6-inch batt with an average R-value of R-3.5 per inch of thickness.

As stated before, if you have some questions regarding the insulation R-value chart, you can use the comments below and we will try to find an answer for you.

Related posts:
  1. All 9 Types Of Insulation Explained (Materials, R-Values, Applications)
  2. Rigid Insulation R-Value Per Inch (+ EPS, XPS, ISO Thickness Charts)
  3. Calculating R-Value: How To Calculate R-Value? (Formula + Units)
  4. ISO R-Value Chart: Thickness Of Polyiso Insulation (1-20 Inches)
  5. Air Duct Insulation R-Values: ASHRAE Requirements (R-1.9, R-6, R-8, R-12)
Insulation R-Value Chart: R-Values Per Inch (For 51 Materials) - LearnMetrics (2024)


What is the best R-value per inch insulation? ›

Rigid foam is the clear winner if you're looking for the highest R-value home insulation you can get. With an R-value of R-4 to R-6.5 per inch of thickness, it's ideal for insulating exterior walls, including basem*nt walls.

How do you calculate R-value of insulation? ›

It will most likely be a fiberglass batt, so multiply the thickness in inches by 3.2 to find out the R-value (or the R-value might be visible on a product label). If the insulation is a foam board or sprayed-on foam, use any visible label information or multiply the thickness in inches by 5 to estimate the R-value.

What is the best R-value for insulation walls? ›

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 R-value of 10 inches of insulation? ›

R Value Of Materials And Depths
Fiberglass (batt)3.1 - 3.431.0 - 34.0
Fiberglass blown (attic)2.2 - 4.322.0 - 43.0
Fiberglass blown (wall)3.7 - 4.337.0 - 43.0
Mineral Wool (batt)3.1 - 3.431.0 - 34.0
9 more rows
Jun 30, 2019

What is the thinnest insulation with the highest 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).

Is it better to use insulation with a low or high R-value? ›

An insulating material's resistance to conductive heat flow is measured or rated in terms of its thermal resistance or R-value -- the higher the R-value, the greater the insulating effectiveness.

What is the R-value calculator? ›

R-value is a measurement that rates how resistant a product is to heat flow, measuring the ability of heat to transfer from one side of an object to another. Our calculator helps you measure what r value for exterior walls you may be looking for, as well as for different applications.

What is the best 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.

Can a house have too much insulation? ›

A home requires air circulation, so if it is too tightly sealed and over-insulated, moisture can build up that causes mold. With too many layers of insulation, mold can even grow in between the layers. Mold in the home can cause allergy flare-ups, allergic reactions, and breathing issues.

Can insulation R-value be too high? ›

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. While you might think that too much insulation can't be bad, there are some significant consequences to consider.

What is the lowest R-value insulation? ›

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.

What material has the best R-value? ›

Vacuum insulated panels have the highest R-value, approximately R-45 (in U.S. units) per inch; aerogel has the next highest R-value (about R-10 to R-30 per inch), followed by polyurethane (PUR) and phenolic foam insulations with R-7 per inch.

Does drywall have an R-value? ›

The higher the R-value, the more effective a material is at preventing heat transfer. Drywall has a low R-value of 0.5. While it is slightly effective at preventing heat transfer, it is not considered an efficient insulator. This is probably due in part to the porous nature of drywall.

Does fiberglass insulation lose R-value over time? ›

Does insulation lose its R value over time? Normally, the types of insulation I am familiar with — fiberglass, foam, mineral wool — don't lose insulation value if not compressed or wetted. Kept dry and undisturbed, the R value should remain for many decades if not a century or more.

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

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.

Which type of insulation has the lowest R-value per inch? ›

Here are the installation methods from lowest to highest average R-value per inch: Blown-in (or loose-fill) insulation. Insulation blankets (batts and rolls) Spray foam insulation.

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