What are wood stove hearth pad R values? an R-value is a measurement of the insulating properties of materials like cement board or ceramic tile and their consistency, wood stove hearth pad R values are easy to calculate with your owner’s manual, and the hearth pad R-value materials chart in this article.

So if you are planning a DIY hearth pad project continue reading because this post will give you insight on what to use for building materials and you will also know what your wood stove hearth pad thickness will need to be before you build it.

Slate Hearth Pad

NY Hearth 54” x 54” Smokey Grey Slate Hearth Pad- Square Wall

R-Value of .84 for Type I


Each Material used in a hearth pad has an R-value, this “R” Value is the amount of insulation protection that the material offers, all materials used in hearth pads or stove boards need to be non-combustible, for example, cement board or ceramic tile, etc, noncombustible means these items are not able to catch fire, and what you are really protecting from heat is the floor below your stove.

The ember pad is designed to protect your home in case of an ember falls out of your stove or heat is transferred out from the bottom of the wood-burning stove to the floor possibly causing a fire or damage.

something to remember is that most modern wood-burning stoves have enough shielding in the bottom that the heat transfer is minimal.

Determine your R-Values

To make these calculations for your DIY hearth pad first look at the R-Values needed in your wood stove user’s manual and from there you can decide what you will need to complete your project.

Always consult your wood stove user manual because every stove is rated differently, there is no one size fits all R-value, and not all stoves need this thermal protection, some will only need ember protection, known as (type 1 protection).

Stove Board Ember Guard

Use with Heating Appliances Requiring Ember Protection, 10-Gauge (3/16″) Steel, 42″ x 42″, Black

Wood stove hearth pad thickness is determined by the material used

This example question below will help you to see how you can calculate your own hearth pad thickness using the wood stove hearth pad R-values chart.

We’re installing our first wood stove in a cabin we built. We want to use quartz for the hearth. We have quarts panels (tiles) we plan to use. We want to put 1/2” cement board on top of the plywood flooring, and top it with the quartz. How thick would the quartz need to be? thanks so much!!

— Marcy

Let’s answer this question for Marcy as an Example only

Let’s see what she might need if she builds a hearth pad with the proper R-value. (this is just an example)

As you can see from the chart below the materials used will go one on top of the other to reach the required number, for example, if your stove manual says you need an R-value of 0.800

For example, let’s say you want to use ceramic tile 1/4″ and Durock Next Gen Cement Board 1/2″ two common materials you can find at almost any hardware store.

The ceramic tile 1/4″ has an R-value of 0.020

The Durock Next Gen Cement Board 1/2″ has an R-value of 0.390

So you just need to add these numbers together.

wood stove hearth pad R valuesPin
Each layer of material used provides more thermal protection, the amount of protection is not dependent on the wood stove hearth pad thickness, but is dependent on the R-value of each material used, wood stove hearth pad R values are stated in your owner manual generally under the section floor protection, and you will only need to calculate R values if the manual states the amount of protection or asks for type 2 protection which is wood stove ember and thermal protection.

To finish this project she will need 2 sheets of Durock Next Gen Cement Board 1/2″ stacked together making them 1″, and then ceramic 1/4″ tile on top of that, coming to exactly the 0.800 R-value that you will need for this mock DIY hearth pad.

Remember this is only an example you will need to make your own calculations with the help of your appliance’s user manual.

Some wood stove hearth pad materials have a higher R-Value than others so you can choose what suits your project.

Hearth Pad R value chartPin
You can save this chart by pinning it with the Pinterest button and easily look back on it for future reference, there is a more detailed chart below.

Another example of this is that Durock Next Gen Cement Board has a lower-Value than Rescor 360 Ceramic Board and both are the same 1/2″ thickness, the difference is the Rescor 360 Ceramic Board has almost 2 1/2 times the R-Value.

So look into using different materials that suit your needs and style so you get exactly the thickness you want when building your pad.

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Wood stove hearth pad materials

You can use many different non-combustible materials to build and finish a hearth, by following the chart below and the information in your user manual you can determine your hearth pad thickness and insulation values.

These two tools will help you will easily understand what you need to get the job done.

Fireplace Hearth Area Rug

Hearth Pilgrim Fireplace Hearth Area Rug

46″ x 28″

Ideal for in front of fireplace hearth or wood burning stoves

Type 1 ember protection

If your stove owner’s manual says you need Type 1 ember protection you don’t need to follow any specific “R” Values, all you will need is any non-combustible surface that is continuous, meaning no gaps and will need to be the thickness that your manual states within.

Type 2 ember and thermal protection

Type 2 protection is for embers and adds thermal protection to the bottom of the floor.

This protection is needed to stop heat from transferring through to a combustible floor.

If you decide to build your own hearth pad with R-values you will need to make it as a continuous surface, again with no gaps, for example, the base can be made of Durock cement board or steel, and both will need to be laid down as one solid sheet, not in two sheets.

Something to remember is that with a type 2 ember and thermal protection, you will need to calculate the R-values stated in your owner’s manual.

Most if not all premade stove boards or hearth pads are type 1 and 2 compliant and are ready to install out of the box in most cases, they should have adequate thermal protection for your wood-burning appliance, always check this with the manufacturer.

Wood stove hearth Pad R Values chart

The chart shows wood stove hearth pad R values of several commonly used materials and should help you determine what to use when building your DIY wood stove hearth pad.

Wood stove hearth pad materialsThicknessR-Value
Ceramic Board ( Rescor 360 )1/2″1.110
Mineral Fiber Board ( Micore 300 )1/2″1.030
Mineral Fiber Board ( Micore 160 )1/2″1.270
Gypsum or Plaster Board1/2″0.450
Cement Board ( Wonderboard )1/2″0.260
Cement Board ( Hardibacker 500 ).42″0.200
Cement Board ( Hardibacker )1/4″0.130
Cement Board ( Durock Next Gen )1/2″0.390
Ceramic Board ( Fiberfrax Duraboard LD )1/2″1.100
Cement Mortar1/2″0.100
Common Brick4″0.800
Common Brick2-1/4″0.450
Ceramic Tile1/4″0.020
Ceramic Pavers1″0.080
These are some of the most common R-value hearth materials available, so feel free to bookmark or share this page so you can always refer back to the r value chart.
Wood stove hearth pad R values conclusion

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