The BrickWood Ceramic Fiber Blanket Guide
Ceramic Fiber Blanket: The Complete Guide to High-Temp Insulation for Pizza Ovens, Kilns and Forges
What ceramic fiber blanket is, 6lb vs. 8lb, how many layers you need, how to install it, and how to handle it safely. Written in plain English for first-time builders.
Ceramic fiber blanket is a lightweight, flexible insulation made from heat-proof ceramic (alumina-silica) fibers. It's rated to 2,300°F, and it wraps the outside of a pizza oven dome to keep the heat inside. BrickWood ceramic fiber blanket comes in a 24-inch by 25-foot roll, 1 inch thick, which covers 50 square feet. You can choose 6lb standard or 8lb heavy-duty density.
Fire brick stores heat. Ceramic fiber blanket keeps it from escaping. That's why it's the #1 upgrade we recommend for every pizza oven kit, and why we tell every builder the same thing: never build a wood-fired oven without it.
Building an oven? Download the FREE step-by-step pizza oven plans. They show exactly where the blanket goes and how to finish over it.
Ceramic Fiber Blanket: Quick Answers
- What it is: high-temperature ceramic fiber insulation, also called ceramic wool, ceramic fire blanket or fiber blanket, and sold under brand names like Kaowool and Inswool.
- Rating: 2,300°F, far hotter than any wood-fired oven gets.
- Size: a 24 in x 25 ft x 1 in roll, 50 sq ft per box.
- 6lb vs. 8lb: same size and rating. 8lb is denser and built for all-day, multi-day or commercial cooking.
- How much: one box wraps 2 layers on every BrickWood oven. Add a 2nd box for cold climates or long cooks.
- Extra boxes: every 2nd box is 10% off, automatically in your cart.
- Install: wrap the dome, hold it down with chicken wire, then stucco. About 30 minutes to wrap.
- Safety: wear an N95 mask, gloves and long sleeves while cutting. Once it's covered, the fibers are sealed in.
- Shipping: FREE shipping. In stock and ships within 1 to 2 days.
What Is Ceramic Fiber Blanket?
Ceramic fiber blanket starts as alumina and silica, the same heat-proof minerals found in fireclay. They're melted and spun or blown into fine fibers, then the fibers are needled together into a soft, flexible mat. HarbisonWalker's blanket, for example, is about 54% silica and 45% alumina, with less than 1% iron.
The finished blanket is mostly air. Millions of tiny air pockets trapped between the fibers are what stop heat from moving through it. HarbisonWalker's product data shows its blanket stores about 95% less heat than dense fire brick, so the blanket doesn't soak up the fire's energy. It holds that energy in.
That's why it's used anywhere heat has to stay put: industrial furnaces and boilers, kilns, forges, foundries, and the dome of nearly every wood-fired pizza oven.
Ceramic fiber blanket words in plain English
| Term | What it means |
|---|---|
| Ceramic fiber blanket | The roll of insulation itself. Also called ceramic wool, ceramic fire blanket, ceramic insulation blanket or just fiber blanket. |
| Density (6lb, 8lb) | How much one cubic foot of blanket weighs: 6 or 8 pounds. It is not the weight of the box. |
| pcf | Pounds per cubic foot, the unit density is measured in. A 6lb blanket is 6 pcf. |
| Needled | The fibers are punched together with barbed needles, which makes the blanket strong without glue. |
| RCF | Refractory ceramic fiber, the technical name for the fiber the blanket is made from. |
| Temperature rating | The hottest the blanket is made to handle: 2,300°F for ours. |
| Kaowool, Inswool, Fiberfrax | Brand names of ceramic fiber blanket from different manufacturers. They're all the same kind of product. |
| Stucco | The cement-based coating that goes over the blanket and chicken wire to seal it in and weatherproof the oven. |
6lb vs. 8lb Ceramic Fiber Blanket: Which One You Need
Both densities come in the same 24 in x 25 ft x 1 in roll, carry the same 2,300°F rating, and wrap the same 2 layers on a BrickWood oven. The difference is how tightly the fibers are packed.
| Feature | 6lb Standard | 8lb Heavy Duty |
|---|---|---|
| Density | 6 pounds per cubic foot | 8 pounds per cubic foot |
| Roll size | 24 in x 25 ft x 1 in (50 sq ft) | 24 in x 25 ft x 1 in (50 sq ft) |
| Box weight | About 28 lb | About 35 lb |
| Box size | 20 in x 20 in x 25 in | 20 in x 20 in x 25 in |
| Temperature rating | 2,300°F | 2,300°F |
| Feel | Soft and easy to shape | Firmer, holds its shape |
| Layers per box on a BrickWood oven | 2 | 2 |
| Best for | Backyard ovens used for pizza nights and weekend cooking | All-day or multi-day baking and commercial use |
Choose 6lb if you're building a backyard oven for pizza nights, family dinners and weekend cookouts. It's what most BrickWood builders use.
Choose 8lb if you plan to cook for long stretches, days rather than hours, or if the oven will see commercial use. The denser blanket is firmer, holds its shape under wire and stucco, and has more fiber packed into every inch.
To order, choose Density at the top of the page. You can mix the two, and every 2nd box is 10% off.
How Hot Can Ceramic Fiber Blanket Get?
BrickWood ceramic fiber blanket is rated to 2,300°F. Manufacturers also list a slightly lower continuous-use limit, about 2,150°F, for blanket that sits at full heat around the clock inside an industrial furnace.
A wood-fired pizza oven doesn't come close. The inside of the oven can reach about 1,000°F, and the blanket sits on the outside of the brick, where it's cooler still. That big margin means the blanket is never working anywhere near its limit.
Why Every Wood-Fired Oven Needs Ceramic Fiber Blanket
Fire brick and refractory cement are heavy, dense materials that soak up and store heat. That's exactly what you want on the inside of an oven. But without insulation, the outside of the dome keeps pulling that heat away and losing it to the air. You burn more wood, the oven takes longer to heat up, and it cools off fast.
Wrapping the dome in ceramic fiber blanket fixes that. Here's what it does for your oven:
- Heats faster with less firewood. More of the fire's heat stays in the oven.
- Stays hot longer, so you get longer baking times and faster re-firing.
- Stays cool outside. Your oven can be 1,000°F inside and cool to the touch outside.
- Hides hairline cracks. If a small crack forms inside the oven, the blanket keeps it from showing on the outside.
- Costs less than a second row of fire brick. One box gives you 2 full layers of insulation.
- Works with almost any finish: stucco, stone, brick, tile or paint.
Never build a pizza oven without it
- An uninsulated oven loses heat through the dome almost as fast as the fire can make it.
- Ceramic fiber blanket is the #1 recommended add-on for every BrickWood oven kit, and it's required for every wood-fired build.
How Many Layers and Boxes Do You Need?
One box of ceramic fiber blanket wraps 2 full layers on every BrickWood oven: the Mattone Barile, Mattone Barile Grande, Cortile Barile and 28-inch Mattone Cupola.
Two layers are enough for warm climates and occasional use. If you live where winters get cold, or you plan to cook all day or across a long weekend, add a 2nd box for a 3rd and 4th layer. Those extra layers can improve your oven's performance by another 25% to 35%. It reaches cooking temperature with less wood, in less time, and stays hot longer.
| Your situation | Layers | Boxes |
|---|---|---|
| Warm climate, pizza nights and weekends | 2 | 1 |
| Cold-winter climate (see the map below) | 3 to 4 | 2 |
| All-day or multi-day cooking | 3 to 4 | 2 (consider 8lb) |
| Commercial use | 3 to 4 | 2 of 8lb |
Save 10% on every 2nd box
Every 2nd box in your cart is 10% off automatically. Buy 2 boxes and one is 10% off. Buy 4 and two are. If you mix 6lb and 8lb, the discount goes on the lower-priced box.
Wrapping something other than a BrickWood oven?
Figure the outside surface area you need to cover, multiply it by the number of layers you want, add about 10% for trimming and overlap, and divide by 50 square feet per box. For a round dome, the outside area is about 6.3 times the radius squared, measured in feet.
How to Install Ceramic Fiber Blanket on a Pizza Oven
Most builders wrap and secure the blanket in about 30 minutes. It goes on after the oven's brick or cement shell is built, and your BrickWood plans show exactly where it goes for your oven.
- Gear up. Put on an N95 mask, gloves, long sleeves and safety glasses before you open the box.
- Cut your lengths. Drape the blanket over the dome and cut it to length with a sharp utility knife.
- Wrap the first layer. Lay it snug against the oven. Where it bunches up on a curve, cut a slit so it lies flat. Butt the edges tightly together so there are no gaps.
- Wrap the second layer. Offset the seams so no seam lines up with one in the layer below. Do the same for a 3rd or 4th layer.
- Hold it down with chicken wire. Stretch chicken wire over the blanket and tie it off with wire so it stays put and doesn't bounce.
- Apply stucco. Cover the wire with stucco to seal the blanket in and give the oven its final shape.
- Finish. Once the stucco cures, finish the oven any way you like.
Snug, not squashed. Pulling the wire too tight crushes the blanket and squeezes out the air that does the insulating.
Finishes you can put over the blanket
The blanket, chicken wire and stucco shell work with almost any finish:
- Painted or natural stucco
- Thin brick or brick veneer
- Stone veneer
- Tile
- A fireplace combo build
How to cut ceramic fiber blanket
A sharp utility knife or a pair of heavy scissors cuts it cleanly. Cut on a scrap board, swap in a fresh blade when it starts to tear instead of slice, and cut slowly to keep dust down. Bag up scraps right away instead of leaving them on the ground.
Is Ceramic Fiber Blanket Safe?
Yes, when you handle it the right way. While you're cutting and fitting it, loose fibers can make your skin itch and irritate your eyes, nose and throat, much like fiberglass. Refractory ceramic fiber is also classified by the International Agency for Research on Cancer (IARC) as a possible human carcinogen (Group 2B), which is why manufacturers call for a respirator while you work with it.
Protect yourself while you work
- Wear a NIOSH-approved N95 mask or better.
- Wear gloves, long sleeves and safety glasses.
- Work outdoors or in a well-ventilated space.
- Clean up with a HEPA vacuum or a damp cloth, never compressed air or a dry broom.
- Wash your work clothes separately.
Once the blanket is wrapped in wire and covered with stucco, the fibers are sealed in. The blanket never touches your food. It's on the outside of the brick, not the inside of the oven.
Is ceramic fiber blanket fireproof?
It won't burn. It's made of ceramic fibers rated to 2,300°F, far above the temperature of a wood-fired oven, fire pit or fireplace.
What if it gets wet?
Water doesn't ruin it. Manufacturer data shows its insulating properties come back once it dries. But wet blanket doesn't insulate while it's wet, and trapped water turns to steam when the oven heats. Keep the blanket covered during your build, seal it with stucco, and if it ever gets soaked, dry the oven out with small fires before you build a big one.
Ceramic Fiber Blanket for Kilns, Forges, Furnaces and Stoves
The same blanket that insulates a pizza oven is a workhorse in other high-heat projects:
- Kilns. Wrap the outside of a kiln or line its lid and door to cut heat loss and firing costs.
- Forges. Ceramic fiber blanket is the standard liner for homemade propane forges. Coat the inside face with a refractory coating made for forges to lock the fibers down and protect them from the flame and from welding flux.
- Furnaces and foundries. Use it as backup insulation behind dense refractory to keep the outer shell cooler.
- Wood stoves and fireplaces. Use it as backup insulation and heat shielding. Always follow your stove maker's instructions and local codes for clearances.
- Smokers and grills. Insulate a firebox to hold steadier temperatures with less fuel.
Ceramic Fiber Blanket vs. the Alternatives
There are a few ways to insulate a pizza oven dome. Here's how they compare:
| Material | How well it insulates a dome | Downsides |
|---|---|---|
| Ceramic fiber blanket | Excellent. Rated to 2,300°F, lightweight and wraps a dome in about 30 minutes | Wear a mask and gloves while cutting |
| Vermiculite or perlite concrete | Good when applied thick | Heavy and messy, takes days to dry, and holds water |
| Insulating fire brick | Good | Slow to cut and fit around a curved dome |
| Household fiberglass | Not suitable | Not made for oven temperatures |
The insulation under the cooking floor is a separate layer from the dome blanket. Follow your plans for what goes there.
Ceramic Fiber Blanket Brands We Ship
Ceramic fiber blanket is made by a handful of major manufacturers. The brand you receive depends on your delivery location, and every one meets the same size and 2,300°F rating.
- HarbisonWalker Inswool (made in the USA)
- Kaowool
- Unifrax Fiberfrax
- Unitherm
- Durablanket
You'll often see brand names like Kaowool, Inswool and Fiberfrax used to mean any ceramic fiber blanket, the same way a popular brand name can become the everyday word for a product.
Ceramic Fiber Blanket Mistakes to Avoid
Don't make these mistakes
- Skipping it. An uninsulated oven wastes wood and never holds heat.
- Using one layer in a cold climate. Two layers is the minimum. Cold winters call for 3 to 4.
- Leaving gaps or lining up seams. Heat finds every gap. Butt the edges tight and offset seams between layers.
- Crushing it. Wire it snug, not squashed.
- Stuccoing straight onto the blanket. Stucco needs chicken wire to grab onto.
- Leaving it out in the rain. Keep it covered until the stucco is on.
- Cutting without a mask. Wear an N95, gloves and long sleeves every time.
- Substituting household fiberglass. It isn't made for oven heat.
Ceramic Fiber Blanket: Frequently Asked Questions
What is ceramic fiber blanket?
Ceramic fiber blanket is a lightweight, flexible insulation made from heat-proof alumina-silica fibers. It's rated to 2,300°F and is used to wrap the outside of pizza oven domes, kilns, forges and furnaces to keep heat in.
Do I need ceramic fiber blanket for my pizza oven?
Yes. Fire brick stores heat but doesn't insulate, so an uninsulated oven loses heat through the dome. Ceramic fiber blanket helps the oven heat faster, stay hot longer and use less wood. Never build a wood-fired oven without it.
What is the difference between 6lb and 8lb ceramic fiber blanket?
The number is the density in pounds per cubic foot, not the box weight. Both are 24 in x 25 ft x 1 in and rated to 2,300°F. 6lb is right for most backyard ovens. 8lb is denser and firmer, and is recommended for all-day or multi-day cooking and commercial use.
How many layers of ceramic fiber blanket do I need?
One box wraps 2 layers on every BrickWood oven: the Mattone Barile, Mattone Barile Grande, Cortile Barile and 28-inch Mattone Cupola. Two layers are enough for warm climates and occasional use. In cold climates or for all-day cooking, add a 2nd box for 3 to 4 layers, which can improve performance by another 25% to 35%.
How hot can ceramic fiber blanket get?
It's rated to 2,300°F, with a continuous-use limit of about 2,150°F. A wood-fired pizza oven reaches about 1,000°F inside, so the blanket works far below its limit.
How much does a box of ceramic fiber blanket weigh?
A box of 6lb blanket weighs about 28 pounds and a box of 8lb blanket weighs about 35 pounds. Both ship in a 20 in x 20 in x 25 in box.
Is ceramic fiber blanket safe?
Yes, when handled correctly. Loose fibers can irritate skin, eyes and throat while you cut and fit it, and refractory ceramic fiber is classified by IARC as a possible human carcinogen (Group 2B). Wear an N95 mask, gloves, long sleeves and safety glasses while working with it. Once it's covered with wire and stucco, the fibers are sealed in.
Is ceramic fiber blanket fireproof?
It won't burn. It's made of ceramic fibers rated to 2,300°F, far above the temperature of a wood-fired oven, fire pit or fireplace.
What happens if ceramic fiber blanket gets wet?
Its insulating properties come back once it dries. Keep it covered during your build and seal it with stucco. If it gets soaked, dry the oven with small fires before building a big one.
How do you install ceramic fiber blanket on a pizza oven?
Wrap the dome snugly, cutting slits where it bunches on curves, and offset the seams between layers. Hold it in place with chicken wire, then cover it with stucco. Most builders finish wrapping in about 30 minutes.
How do you cut ceramic fiber blanket?
Use a sharp utility knife or heavy scissors, and wear a mask and gloves. Bag up scraps right away to keep fibers out of the air.
Is Kaowool the same as ceramic fiber blanket?
Yes. Kaowool, Inswool and Fiberfrax are brand names of ceramic fiber blanket. Ceramic wool, ceramic fire blanket and fiber blanket are other common names for the same product.
Which brand of ceramic fiber blanket will I receive?
It depends on your delivery location. Brands we ship include HarbisonWalker Inswool (made in the USA), Kaowool, Unifrax Fiberfrax, Unitherm and Durablanket. All meet the same size and 2,300°F rating.
Can I use fiberglass insulation instead?
No. Household fiberglass insulation isn't made for oven temperatures. Use ceramic fiber blanket rated for high heat.
Do you offer a discount on extra boxes?
Yes. Every 2nd box is 10% off automatically in your cart. Buy 2 boxes and one is 10% off. Buy 4 and two are. If you mix 6lb and 8lb, the discount goes on the lower-priced box.
How fast does ceramic fiber blanket ship?
It's in stock and ships within 1 to 2 days, with FREE shipping.
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Insulate your oven the right way
Choose 6lb or 8lb at the top of the page. Every 2nd box is 10% off, and shipping is FREE.
Not sure which density or how many boxes you need? Our team has helped thousands of backyard builders since 2013, and we're happy to help you get it right.
Specifications are typical values from manufacturer data and can vary slightly by brand. Box weights are approximate.
