If you’re planning to install insulation in a high-temperature application, ensuring the insulation material you choose can withstand the parameters is crucial for an effective and safe process. 

Various highly heat-resistant insulation materials can be used to do their job effectively in resisting the transfer of heat flow. These include fiberglass, cellulose, mineral wool/rock wool, ceramic fiber, vermiculite, polycrystalline fiber, and mica insulation.

If you wish to use high-temperature insulation, it’s essential to know what makes it highly heat-resistant, its heat resistance rating, and when you should use it. 

Here, we’ll look at the various high heat-resistant insulation types, their properties, advantages, and how to improve insulation heat resistance.

When Do You Need a High Heat Resistance Insulation?

High-temperature insulation or high heat resistance insulation is a type of insulation that is specifically designed for extreme temperatures. This insulation type typically comprises three components: the outer layer, the inner layer, and the insulating material.

High-temperature insulation has a maximum capacity for high heat resistance, reducing the transfer of heat energy from various hot components and surrounding elements to prevent potential fire hazards. This also means this insulation type doesn’t catch fire and burn easily. 

So when do you need high heat resistance insulation? 

Some traditional insulating materials begin to degrade and burn when the temperatures approach 600°F and melt above 1000°F, so it would require extra heat resistance insulation.

High-temperature insulation is mainly used for applications experiencing elevated temperatures, such as manufacturing and industrial applications. It’s needed to control the operating temperatures for optimal consistency and efficiency and helps extend the equipment’s life while providing safety measures. However, it can also be used for residential use in places exposed to high temperatures, such as chimneys

Examples of residential applications that require high heat resistance insulation include furnaces, boilers, ovens & kilns, and dryers. The following applications for industrial and manufacturing use include industrial processing equipment, high-pressure steam piping, flanges, valves, expansion joints, turbines, chillers, incinerators, compressors, and heat exchangers.

Insulation Heat Resistance Chart

Thermal resistance is a material’s ability to resist the flow of heat. So the higher the heat resistance, the better its insulation properties. The insulation material’s thermal resistance or R-value may vary depending on the material’s thickness and the specific material used. 

Below is the chart of heat resistance of different insulation types.

Calcium Silicate -1806501200
Cellular Glass-260-450480900
Elastomeric foam-55-70120 250
Mineral Wool, Ceramic Fiber12002200
Mineral Wool, Glass032250 480
Mineral Wool, Stone0327601400
Phenolic foam150300
Polyisocyanurate or polyiso-180-290150300

Source: ResearchGate Study on the temperature range of common insulation materials.

Are There Specific Types of Insulation For Extreme Temperatures?

There is a range of insulation types suitable for high-temperature usages for both commercial and residential uses.

Fiberglass Insulation

Fiberglass insulation is highly heat-resistant and non-combustible because it’s made from glass fibers. In addition, since fiberglass is non-combustible, it cannot burn easily and doesn’t need to be treated with fire retardants.

It can withstand high temperatures up to 1000°F, with an ignition temperature of around 1,112°F. However, although fiberglass is non-flammable, it can melt when exposed to a particular temperature of about 1500°F and ultimately melt when it reaches 2050°F.

Cellulose Insulation

Cellulose insulation is another insulation type that can be used for extreme temperatures. It’s made of 75 to 85% recycled paper fiber or wood and chemically treated with a fire retardant, making it highly heat-resistant.

Among the insulation types, Cellulose insulation has a Class 1 fire rating, meaning it has a flame spread of 25 and a smoke development of 50 or less. It withstands elevated temperatures of about 1,200°F. 

Mineral Wool/Rock Wool Insulation

Mineral wool or rock wool insulation has excellent heat-resistant properties as it is made of mineral rock, a naturally non-combustible material. As a result, it can withstand high temperatures above 1832°F and starts to melt at 2,200°F. This makes it an ideal insulating material for applications under extreme heat like ovens and boilers. It’s also commonly used in the piping and construction industry.

Vermiculite Insulation

Vermiculite insulation is a high-temperature insulating material made from naturally occurring minerals resembling mica. It can withstand extreme temperatures of about 2012 to 2102° F.

Ceramic Fiber Insulation

Ceramic fiber insulation is a lightweight insulating material with high-temperature resistance, low thermal conductivity, and good thermal stability. It can withstand extreme temperatures of 2000º F to 2300ºF.

This makes Ceramic fiber insulation suitable for extremely high-temperature applications, including expansion joints, furnaces, kilns, laboratory ovens, chimneys, high-temperature gaskets, boiler lining, and reformers. 

Polycrystalline Fiber Insulation

Polycrystalline Fiber Insulation is another remarkable insulating material for high temperatures. It’s made from silicon and aluminum using sol-gel technology. It can endure extreme temperatures up to 2912º to 3000º F. Common applications for this insulation type include furnace linings and ceramic kilns.

Mica Insulation

Mica insulation is a non-flammable insulating material made of naturally occurring materials like silicate minerals. It has excellent electrical and thermal properties, low thermal conductivity, and high thermal stability, making it an excellent thermal insulator.

Mica insulation can withstand high temperatures of about 1832° F. In addition, it’s often used in blast furnaces, aluminum plants, and critical wiring circuits. 

Tips for Improving Insulation Heat Resistance

Here are various tips you can consider in improving insulation’s heat resistance.

Ensure Proper Installation

Improper installation can lead to loss of R-value because the insulation cannot reach its maximum potential with gaps and air drafts within. It also leads to moisture or water retention and saturation, encouraging mold and bacteria growth that can further lose R-value and damage the insulation.

In addition, if the insulation is compressed or compacted, it will not provide its full rated R-value because it has already lost its air pockets inside, which defines an insulation’s thermal resistance properties.

This is why properly installing insulation is one of the most important aspects of an insulation’s thermal performance. It’s best to let professional insulation specialists install the insulation as most insulation has complex processes and ensures safety.

Ensure Proper Ventilation

It’s also important to ensure proper ventilation as poor ventilation can produce excessive moisture and trap cold drafts, which can threaten and reduce the insulation’s heat resistance.

Remove Leaks and Gaps

Detecting any leak and ensuring the area is draught-free is also important as it prevents cracks and gaps that cause cold spots and air drafts. This also helps improve the ventilation needed in the area.

To do this, seal and caulk any leaks, gaps, and vents using sealant strips, sealer, or putty. You can also add rubber weatherstripping around the windows, between the sides and bottom of the door to seal all gaps. This will also help prevent cold air from entering the space and warm air from escaping in the winter.

Follow Building Codes and Regulations

Another important thing to consider is to know the local building codes, along with the climatic zone and recommended thickness in the area, as these significantly determine the required R-value in a specific location. 

The Department of Energy categorized the country into seven zones for the recommended insulation levels, which must be adequately met. Failure to do this can affect the insulation’s overall thermal resistance performance.


Justin's been in construction for over 20 years in both new build and renovation. With experience in both commercial and residential construction, he specializes in healthier and more energy-efficient homes.

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