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)

FAQs

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

Comparative Insulation R-Values
Insulation TypeR-Value per Inch
Fiberglass (batts)2.9 – 3.8
Cellulose (loose)3.1 – 3.8
Stone Wool (loose)2.2 – 3.3
Stone Wool (batts)3.3 – 4.2
7 more rows
Apr 6, 2024

How do you calculate the R-value per inch? ›

In order to calculate the R-value of a particular piece of insulation, you divide the thickness of the material by its thermal conductivity. Thermal conductivity measures the rate at which temperatures transmit through an insulating material.

What is the value of R 50 insulation? ›

Conventional insulation requires thicknesses of up to 15″ to reach an R-Value of 50. R-50 Systems' Rich-E-Board™ provides this same R value at 1″. The ultra-thin, lightweight design decreases costs of building modifications and structural retrofits, while creating more usable space for living and/or operations.

What is the R-value of 1 inch insulation board? ›

R Value by Material
Material TypeR ValueCost / sq. ft. per R value
Closed cell polystyrene spray foam (1 inch thick)6.5$0.25
Expanded polystyrene foam board (1 inch thick)3.8-4.4$0.07
Extruded polystyrene foam board (1 inch thick)5$0.10
Polyisocyanurate foam board (1 inch thick)6.5$0.10
3 more rows
Apr 23, 2020

What insulation has the best R-value? ›

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 basement walls.

What is the difference between RSI and R-value? ›

The two thermal resistance values you'll encounter are the RSI and R-Value. The R-Value is an imperial system unit of measurement (ft2·°F·h/BTU) and the RSI Value is a metric system unit of measurement (m2·K/W). The higher the resistance value, the slower the rate of heat transfer through the insulating material.

What R-value is 12 inches? ›

R Value Of Materials And Depths
MaterialR-value/in12"
Fiberglass (batt)3.1 - 3.437.2 - 40.8
Fiberglass blown (attic)2.2 - 4.326.4 - 51.6
Fiberglass blown (wall)3.7 - 4.344.4 - 51.6
Mineral Wool (batt)3.1 - 3.437.2 - 40.8
9 more rows
Jun 30, 2019

What is the R ratio of materials? ›

The critical R-ratio is defined as the ratio of the compressive strength to the tensile static strength of the examined materials.

What is the R-value for 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.

Is there a big difference between R13 and R15? ›

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.

Can you over insulate a house? ›

The short answer is, yes, you can over-insulate your home. While your home should be well-insulated against the cold and keep you cool during hot summer months, that doesn't mean you should cram the walls full. Read on to discover why over-insulating a home isn't a good idea.

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).

What is the R-value of a 2 inch pink foam board? ›

With an R-value of 13.1 for a 2" thick sheet only two 2" sheets are required to achieve R-25. 2. Extruded polystyrene or XPS (foam is usually pink or blue) XPS has an R-value of 5 per inch of thickness requiring 5" of insulation to achieve R-25.

Why is R19 thicker than 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”.

What is the difference between R13 and R19? ›

The higher the R-value, the greater the insulating power. R13 insulation is made from lower-density fiberglass and is typically used in walls that are 2×4 studs. R19 insulation is made from higher-density fiberglass insulation and is typically used in walls that are 2×6 studs.

What is the R-value of 12 inches of fiberglass insulation? ›

R Value Of Materials And Depths
MaterialR-value/in12"
Fiberglass (batt)3.1 - 3.437.2 - 40.8
Fiberglass blown (attic)2.2 - 4.326.4 - 51.6
Fiberglass blown (wall)3.7 - 4.344.4 - 51.6
Mineral Wool (batt)3.1 - 3.437.2 - 40.8
9 more rows
Jun 30, 2019

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