Ceramic Fiber Blanket: The Complete Guide for Pizza Oven Insulation

FIRESIDE • MATERIALS GUIDE

Ceramic Fiber Blanket: The Complete Guide for Pizza Oven Insulation

What it is, why pizza ovens need it, how 6 lb and 8 lb densities compare, major brands to know, installation tips, safety, moisture protection, and how much insulation your oven really needs.

IMAGE PLACEHOLDER
Replace with a close-up or cutaway photo showing ceramic fiber blanket wrapped around a brick pizza oven.

Ceramic fiber blanket is one of the most important performance materials in a masonry pizza oven. Wrapped around the refractory oven shell, it slows heat loss so the cooking chamber heats more efficiently, stays hot longer, uses less fuel, and supports better retained-heat cooking after the fire has died down. BrickWood uses high-temperature ceramic insulation in its oven systems because masonry stores heat—but insulation helps keep that heat where you want it. This guide explains the material from the ground up, including density, brands, thickness, installation, safety, and the differences between 6 lb and 8 lb blanket.

Ceramic Fiber Blanket — Quick Answers

  • 6 lb and 8 lb refer to blanket density: pounds per cubic foot (pcf), not the temperature rating.
  • At the same thickness and product family, 8 pcf blanket is denser, stronger, and often shows slightly lower thermal conductivity than 6 pcf blanket.
  • For pizza ovens, blanket belongs outside the refractory cooking chamber—not exposed where food is cooked.
  • A 1 in × 24 in × 25 ft roll covers 50 sq. ft.; BrickWood sells both 6 lb and 8 lb rolls.
  • Use refractory insulation rated for the application; household fiberglass is not a direct substitute.

What Is Ceramic Fiber Blanket?

Ceramic fiber blanket is a lightweight, flexible refractory insulation made from high-temperature fibers formed into a needled blanket. Traditional products are commonly alumina-silica refractory ceramic fiber (RCF); newer low-biopersistence or alkaline-earth-silicate (AES) product families are also available. Unlike ordinary building insulation, these materials are engineered for furnaces, kilns, boilers, refractory linings, and other equipment operating at temperatures far beyond residential wall or attic insulation.

Its value comes from very low thermal conductivity and low heat storage. The fibers create a highly porous structure that resists heat transfer without adding the weight and thickness of another masonry layer.

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Cross-section: refractory shell → ceramic fiber blanket → reinforced weatherproof finish.

Why Does a Brick Pizza Oven Need Ceramic Fiber Insulation?

Firebrick and refractory castables are excellent at absorbing and storing heat, but they are not efficient insulation. Without an insulating layer, heat continuously conducts outward through the oven shell and into the surrounding masonry and air. Ceramic fiber blanket slows that heat flow so more energy stays in the cooking chamber.

  • Faster heat-up because less energy is lost outward
  • Lower firewood or gas consumption for a given cooking temperature
  • Slower temperature drop after the fire is reduced or removed
  • Longer retained-heat cooking windows for bread, roasts, vegetables, and slow cooking
  • Lower exterior temperatures than an otherwise identical uninsulated assembly
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“Where the Heat Goes” visual: insulated vs. uninsulated oven with heat arrows.

What Happens If You Build a Pizza Oven Without Insulation?

An uninsulated masonry oven may still get hot, but it has to fight constant heat loss. That typically means longer warm-up, more fuel, faster cooling, hotter surrounding masonry, and weaker retained-heat performance. The problem becomes especially obvious during long cooking sessions or in cold and windy weather.

  • Longer heat-up times
  • More firewood consumption
  • Faster temperature loss
  • Shorter cooking sessions between firings
  • Poorer overnight heat retention
  • Very hot outer masonry or enclosure surfaces
  • More difficult temperature recovery after opening the door or loading food

What Do “6 lb” and “8 lb” Mean?

The number is blanket density, expressed in pounds per cubic foot (pcf). A 6 lb blanket is about 96 kg/m³; an 8 lb blanket is about 128 kg/m³. Density is not the same as temperature rating. Morgan Thermal Ceramics, for example, lists standard Kaowool blanket in 4, 6, and 8 pcf densities with the same 2300°F classification temperature.

In simple terms: 8 lb blanket packs more fiber into the same volume. That generally makes it stronger and can modestly improve thermal performance at the same thickness, but it also makes it heavier and more expensive.

96 kg/m³ • STANDARD DENSITY

6 lb Ceramic Fiber Blanket

A strong all-around choice for residential pizza ovens. It is flexible, easy to conform around curves, and usually the lower-cost way to build multiple inches of insulation.

PROS
  • Excellent insulation for most residential ovens
  • Lighter and easier to cut, overlap, and shape
  • Usually the more economical choice
  • Widely available in common 1-inch rolls
CONS
  • Lower tensile strength than a comparable 8 pcf blanket
  • At high mean temperatures, thermal conductivity can be slightly higher than 8 pcf in the same product family

https://brickwoodovens.com/collections/refractory-materials/products/ceramic-fiber-insulation-blanket-6lb-50sf-1in-x24in-x25ft-for-kilns-ovens-pizza-ovens-furnaces-forges-stoves

128 kg/m³ • HIGHER DENSITY

8 lb Ceramic Fiber Blanket

A denser blanket with more fiber per cubic foot. Manufacturer data for families such as Superwool Plus show higher tensile strength and modestly lower thermal conductivity than 6 pcf at equal thickness.

PROS
  • Denser and more robust during installation
  • Typically higher tensile strength
  • Can provide modestly better thermal performance at equal thickness
  • Useful when maximizing performance in limited space
CONS
  • Heavier and usually more expensive
  • Often a smaller gain than simply adding more total insulation thickness
  • Density does not compensate for an inadequate temperature rating

https://brickwoodovens.com/collections/refractory-materials/products/ceramic-fiber-insulation-blanket-8lb-50sf-1in-x24in-x25ft-for-kilns-ovens-pizza-ovens-furnaces-forges-stoves

BrickWood recommendation: for most backyard ovens, 6 lb blanket is the best value. Choose 8 lb when you want the denser, tougher material or when you are trying to squeeze the best performance from a fixed insulation thickness. If combining densities, place the denser 8 lb layer closest to the refractory shell, then add 6 lb layers outside it.

Major Ceramic Fiber Blanket Brands to Know

Ceramic fiber blanket is a product category, not one single brand. Specifications vary by manufacturer and product family, so compare the data sheet—not just the name on the carton. BrickWood may source from different refractory suppliers depending on delivery location.

Kaowool®

Morgan Thermal Ceramics

One of the best-known traditional refractory ceramic fiber names. Morgan’s standard Kaowool blanket is offered in 4, 6 and 8 pcf densities, with a 2300°F classification temperature and 2000°F continuous-use rating.

Fiberfrax® / Durablanket®

Alkegen

A long-established refractory fiber family used in industrial furnaces and heat-processing equipment. Fiberfrax blanket lines include multiple density and temperature grades; Durablanket products are commonly specified in 6 and 8 pcf constructions.

Superwool®

Morgan Thermal Ceramics

A low-biopersistence AES fiber family. Superwool Plus blanket is offered in 6, 8 and 10 pcf densities, with a 2190°F classification temperature and 1920°F continuous-use temperature.

Unitherm Ceramic Fiber Blanket

UniTherm International

Commercial alumina-silica blanket sold in common 6 and 8 pcf densities. Current product listings show 2300°F max-use products in standard roll sizes used for furnaces, kilns and high-temperature insulation.

Inswool® / Insulfrax® / Isofrax®

Refractory distribution / Alkegen families

Names commonly encountered through refractory distributors. Some are conventional RCF products and others are low-biopersistence alternatives, so always verify chemistry, density and temperature rating on the exact product data sheet.

MaxWool® and other regional brands

Specialty refractory manufacturers

Many reputable manufacturers sell comparable needled high-temperature blankets. Brand recognition is useful, but density, chemistry, thickness, temperature classification, tensile strength and thermal conductivity are the specifications that matter.

Important: “Kaowool” is a trademarked brand name, but it is often used casually as a generic term for ceramic fiber blanket—much like people say “Kleenex” for facial tissue. When buying insulation, confirm the actual manufacturer and data sheet rather than relying on a generic marketplace title.

How Hot Is Ceramic Fiber Blanket Rated For?

Temperature language can be confusing. “Classification temperature,” “maximum use,” and “continuous use” are not interchangeable. A blanket may be classified at 2300°F while the manufacturer recommends a lower long-term operating temperature. For a pizza oven, the correct product should be selected by its manufacturer data sheet and used outside the refractory cooking chamber.

Examples from current manufacturer data: standard Kaowool blanket is classified to 2300°F with a 2000°F continuous-use rating; Superwool Plus is classified to 2190°F with a 1920°F continuous-use rating. UniTherm lists common alumina-silica blankets with a 2300°F maximum-use limit and approximately 1922°F continuous use.

Do not choose insulation because the listing merely says “fireproof” or “heat resistant.” Verify the actual temperature data.

How Thick Should Ceramic Fiber Blanket Be?

For most masonry pizza ovens, insulation is built in layers. Thickness generally has a bigger impact on heat loss than density alone: adding another inch of suitable blanket creates more resistance to heat flow. The right thickness depends on oven size, climate, how often you cook, how long you want to retain heat, and how much room the exterior enclosure allows.

  • 2 inches: a practical baseline for many backyard ovens
  • 3 inches: stronger retained-heat performance for frequent users or colder climates
  • 4 inches: useful for builders prioritizing long cooking windows and overnight heat retention
  • Beyond that: gains continue, but with diminishing returns, added cost, and a larger finished enclosure

A BrickWood 50 sq. ft. roll is 1 inch thick × 24 inches wide × 25 feet long. One roll may create multiple layers depending on the oven model and how much overlap is used. Calculate from the actual outer surface area of your refractory shell rather than relying on a universal “one roll fits all” rule.

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Layer diagram showing 1 in, 2 in, 3 in and 4 in total blanket thickness.

Where Does Ceramic Fiber Blanket Go on a Pizza Oven?

Blanket wraps the outside of the refractory oven shell. A typical sequence is: cooking chamber / refractory shell → ceramic fiber blanket → reinforcement or enclosure system → weather-resistant exterior finish. It should not be left exposed inside the food chamber.

What About Under the Cooking Floor?

The hearth needs insulation too, but blanket is usually not the structural product used directly under a heavy cooking floor. Rigid ceramic fiber board, calcium silicate board, vermiculite/perlite insulating concrete, or another load-bearing refractory insulation is commonly used beneath the floor depending on the oven design. Blanket and board solve the same heat-loss problem in different locations.

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Cutaway showing blanket around dome/barrel and rigid insulation board under cooking floor.

Ceramic Fiber Blanket vs. Other Insulation Materials

Vermiculite / Perlite Insulating Concrete

Low cost and useful for shaping or filling large spaces, but generally requires much more thickness than high-performance fiber blanket and can hold construction moisture.

Fiberglass Building Insulation

Not a direct substitute. Ordinary residential fiberglass products and facings are not intended for direct service next to pizza-oven refractory temperatures.

Mineral Wool / Rock Wool

Some high-temperature mineral wool products can be useful in appropriate locations, but products vary widely in binder chemistry, temperature rating, density and shrinkage. Do not assume any mineral wool is interchangeable with ceramic fiber blanket.

Ceramic Fiber Board

Rigid and load-bearing compared with blanket. Often better suited beneath the cooking floor or where a flat, firm insulating layer is required.

Insulating Firebrick

Durable refractory insulation with structural value, but heavier, thicker and more labor-intensive than wrapping an oven shell with blanket.

How Do You Install Ceramic Fiber Blanket Around a Pizza Oven?

Follow the oven plans and the insulation manufacturer’s instructions. A typical masonry-oven installation is straightforward, but neat seams and full coverage matter.

  1. Let the refractory shell reach the stage specified by your build instructions before wrapping it.
  2. Measure and dry-fit blanket sections so the refractory shell is fully covered.
  3. Cut with a sharp utility knife or insulation knife while wearing the PPE recommended by the manufacturer.
  4. Butt or slightly overlap seams so there are no obvious heat-leak gaps.
  5. Add subsequent layers with seams staggered when practical.
  6. Use temporary wire, mesh, clips, or the enclosure system recommended by the oven design to keep the blanket in place.
  7. Cover and protect the insulation with the specified reinforcement and weather-resistant exterior assembly.

Should You Compress Ceramic Fiber Blanket?

Avoid unnecessary compression. Fiber insulation works because its structure traps air and resists heat flow. Some compression is unavoidable where layers overlap or are held in place, but crushing a 1-inch blanket into a much thinner space can reduce the benefit you expected from that inch of insulation.

Do Gaps Matter?

Yes. Large gaps create localized thermal bridges. Treat the insulation layer like a winter coat for the oven: complete coverage is more valuable than having premium material with bare spots.

Can Ceramic Fiber Blanket Get Wet?

The finished oven assembly should be designed to keep the insulation dry. Water in or around refractory and insulation dramatically increases the amount of energy needed during heat-up because the oven must first drive off moisture. Repeated saturation can also create freeze-thaw concerns and damage exterior finishes.

The blanket is insulation—not the weather barrier. Your finished enclosure, stucco, flashing, chimney penetrations, caps, and other exterior details must shed rain and prevent water entry.

If an oven has become saturated, do not assume a normal pizza fire is the best first step. Follow the oven manufacturer’s drying/curing guidance and bring temperatures up gradually.

Is Ceramic Fiber Blanket Safe to Use Around a Pizza Oven?

Ceramic fiber products are widely used as industrial refractory insulation, but cutting and handling fiber blanket can release airborne fibers and dust. Safety guidance depends on the exact chemistry and manufacturer, so read the current Safety Data Sheet (SDS) for the product you receive.

  • Wear the respiratory, eye, skin, and hand protection specified by the SDS and manufacturer.
  • Minimize dust: use sharp cutting tools and avoid unnecessary tearing, shaking, or compressed-air cleanup.
  • Work in a well-ventilated area and keep bystanders away from active cutting.
  • Clean the work area using methods recommended by the manufacturer rather than dry sweeping airborne fibers.
  • Enclose the blanket in the finished oven assembly; do not leave it exposed in the cooking chamber or where food contacts it.

Traditional refractory ceramic fiber (RCF) and newer low-biopersistence/AES fibers are different material classes. Product labels such as Kaowool, Fiberfrax, Superwool, Insulfrax, and Isofrax may represent different chemistries and regulatory classifications. Always use the SDS for the exact product.

Common Pizza Oven Insulation Mistakes

  • Skipping insulation because the firebrick “already holds heat.”
  • Using ordinary household fiberglass because it looks similar.
  • Insulating the dome or barrel but ignoring heat loss through the hearth.
  • Buying by brand nickname alone without checking density, chemistry, thickness, and temperature rating.
  • Compressing the blanket aggressively to make it fit a too-small enclosure.
  • Leaving gaps, especially around transitions, shoulders, and chimney penetrations.
  • Letting the insulation become saturated because the exterior finish was not waterproofed.
  • Leaving ceramic fiber exposed inside the cooking chamber.
  • Assuming 8 lb density automatically beats 6 lb regardless of total thickness and price.

Signs Your Pizza Oven May Not Have Enough Insulation

  • The exterior gets extremely hot very quickly
  • The oven burns substantially more wood than expected
  • Temperature drops rapidly after the active fire is reduced
  • It is difficult to maintain pizza-baking temperatures
  • The oven has very little usable heat the next morning
  • Reheating takes nearly as long as the initial firing

Can you add insulation later? Sometimes—but once veneer, stucco, brick, roofing, or another enclosure is finished, reaching the refractory shell may require major demolition. That is why insulation is one of the worst places to cut costs during the original build.

Ceramic Fiber Blanket FAQ

Does a pizza oven really need insulation?

For a high-performance masonry oven, yes. Refractory mass stores heat; insulation reduces the rate at which that stored heat escapes.

Is 8 lb blanket always better than 6 lb?

Not automatically. At equal thickness, 8 pcf is denser, stronger, and can have somewhat lower thermal conductivity, but total insulation thickness, product chemistry, temperature rating, and budget matter more than density alone.

How much ceramic fiber blanket do I need?

Measure the outer surface of the refractory shell and account for overlaps and multiple layers. BrickWood rolls are 50 sq. ft. each at 1 inch thick, 24 inches wide, and 25 feet long.

Can I use fiberglass insulation around a pizza oven?

Do not substitute ordinary residential fiberglass for refractory blanket beside the hot oven shell. Use insulation specifically rated and documented for the intended high-temperature service.

Can ceramic fiber blanket burn?

Proper refractory ceramic or AES blanket is noncombustible insulation intended for extreme heat, but binders, facings, adhesives, or other nearby materials can have different limits. Verify the exact product system.

Can I put stucco directly over the blanket?

Most oven systems need a reinforcing or support layer so the exterior finish has a stable substrate. Follow your oven plans for mesh, shell, enclosure, or other support before applying the final finish.

Does more insulation keep helping forever?

More thickness continues to reduce heat flow, but each added layer costs money and increases enclosure size. Most residential builders choose a practical balance rather than maximizing thickness indefinitely.

Choose the Ceramic Fiber Blanket That Fits Your Build

BrickWood offers both 6 lb and 8 lb ceramic fiber blanket in 50 sq. ft. rolls. The 6 lb blanket is our best-value choice for most residential pizza ovens; the denser 8 lb blanket is available for builders who want higher handling strength and maximum performance at a fixed thickness.

6 lb • 50 sq. ft. Roll https://brickwoodovens.com/collections/refractory-materials/products/ceramic-fiber-insulation-blanket-6lb-50sf-1in-x24in-x25ft-for-kilns-ovens-pizza-ovens-furnaces-forges-stoves 8 lb • 50 sq. ft. Roll https://brickwoodovens.com/collections/refractory-materials/products/ceramic-fiber-insulation-blanket-8lb-50sf-1in-x24in-x25ft-for-kilns-ovens-pizza-ovens-furnaces-forges-stoves

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Last updated: September 2026