Fireside • Build It Right
Pizza Oven Insulation: What to Use and How Thick to Go
A pizza oven loses heat in two directions: up through the dome or barrel and down through the floor. Insulate both and your oven heats faster, burns less wood and stays hot for hours. Here’s what to use in each spot, how much you need, and how it goes on.
Insulate a pizza oven in two places. Wrap the outside of the dome or barrel in ceramic fiber blanket: 2 layers for most backyard ovens, 3 to 4 layers in cold climates or for all-day cooking. Then put insulation under the firebrick cooking surface: a 5 to 1 mix of perlite or vermiculite and Portland cement, 2 inches thick for most owners and 4 inches for heavy users.
Firebrick and castable refractory are built to soak up heat and give it back. They are not insulators. Without a layer of insulation around them, the heat you just put into the brick keeps leaking out into the air and into the concrete base. Insulation is what turns a hot pile of brick into an oven that bakes bread the next morning.
Pizza Oven Insulation: Quick Answers
- Dome or barrel: ceramic fiber blanket, rated to 2,300°F, wrapped over the outside of the brick.
- How many layers: 2 for warm climates and weekend use, 3 to 4 for cold winters or long cooks. One box wraps 2 layers on any BrickWood oven.
- Under the floor: 5 parts perlite or vermiculite to 1 part Portland cement, in the insulation void of the hearth slab.
- How thick under the floor: 2 inches for most owners, 4 inches for bread bakers and heavy users.
- Never use: household fiberglass, foam board, rock wool batts or plain concrete next to the heat.
- Finish: chicken wire over the blanket, then stucco or any finish you like.
- Is it required? Yes. Never build a wood-fired oven without it.
Why Does a Pizza Oven Need Insulation?
Because firebrick stores heat but doesn’t hold onto it. A firebrick barrel or castable dome is a heat battery. Insulation is the cover that keeps the battery from draining. Without it, an oven loses heat through its walls almost as fast as the fire can make it.
Here’s what good insulation does for your oven:
- Heats up faster on less firewood. More of the fire’s heat goes into the brick, not out into the yard.
- Stays hot for hours. Roasting, baking and next-day cooking all run on stored heat. See what you can cook in a pizza oven.
- Bakes a better bottom crust. An uninsulated floor lets the concrete base pull heat out of the firebrick cooking surface, and pizzas come out pale underneath.
- Stays cool outside. An oven can be 1,000°F inside and cool to the touch outside.
- Protects the finish. Less heat reaching the stucco, stone or brick means less stress on the outer shell.
Where Does Insulation Go on a Pizza Oven?
Every wood-fired oven has two insulation zones. Skip either one and the heat finds its way out.
Over the top: ceramic fiber blanket wraps the outside of the firebrick barrel or castable dome, held down with chicken wire and sealed under stucco or your finish of choice.
Under the floor: a layer of insulating concrete fills a void in the hearth slab, under a sand bed and the firebrick cooking surface.
| Layer, from the fire out | Over the top | Under the floor |
|---|---|---|
| 1. Heat storage | Firebrick barrel or castable dome | Firebrick cooking surface, laid dry |
| 2. Bed | None | 1 to 2 inches of all-purpose sand for leveling |
| 3. Insulation | 2 to 4 layers of ceramic fiber blanket | 2 to 4 inches of 5:1 perlite or vermiculite and Portland cement |
| 4. Structure or shell | Chicken wire and stucco | The concrete hearth slab |
| 5. Finish | Stucco, stone, brick or tile | The block base and its veneer |
Keep each material in its place. The blanket never goes under the floor, because it’s soft and gives the firebrick nothing firm to sit on. And the perlite mix never goes on the dome or barrel: it’s heavy, it crushes the blanket and it adds little. Another layer of blanket insulates far better.
Best Insulation for a Pizza Oven
The best pizza oven insulation is ceramic fiber blanket over the dome or barrel and a perlite or vermiculite insulating concrete under the floor. Both are cheap, easy for a first-time builder and made for high heat. Here’s how they compare with everything else people try.
| Material | Where it goes | Verdict |
|---|---|---|
| Ceramic fiber blanket | Over the dome or barrel | The best choice. Rated to 2,300°F, light, flexible, wraps an oven in about 30 minutes |
| Perlite or vermiculite + Portland cement | Under the floor, in the hearth slab | The best value. Mix 5 to 1 by volume. Perlite dries in about 2 days, vermiculite in 5 to 6 |
| Insulating castable | Under the floor | Works well and is ready in about a day, but costs about 3 to 4 times as much as a perlite mix |
| Ceramic fiber board | Under the floor | Insulates best per inch but costs the most and usually ships by freight. Mostly worth it for ovens fired for days at a time |
| Insulating firebrick | Over the top or under the floor | Works, but slow to cut and fit around a curve, and costly |
| Perlite concrete over the dome | Not recommended | Heavy, slow to dry, holds water, and it crushes the blanket. Another layer of blanket insulates far better |
| Household fiberglass, rock wool batts | Never | Not made for oven heat. The facings and binders burn |
| Foam board, spray foam | Never near the heat | Plastic foam melts and gives off toxic fumes |
| Plain concrete or sand | Not insulation | Both pull heat out of the oven. Sand under the floor is only a leveling bed |
You’ll also hear ceramic fiber blanket called by brand names like Kaowool. It’s the same kind of product. Our ceramic fiber blanket page covers 6 lb vs. 8 lb density, specs and safe handling, and our perlite and vermiculite page covers the mix, the right bag to buy and where to find it locally.
How Thick Should Pizza Oven Insulation Be?
It depends on your climate and how you cook. Pizza nights and weekend cookouts need less than all-day bread baking or a cabin in Minnesota. Here’s the short version.
Over the dome or barrel: 2 to 4 layers of blanket
Each layer of blanket is 1 inch thick. One box, a 24-inch by 25-foot roll, wraps 2 full layers on every BrickWood oven: the Mattone Barile, Mattone Barile Grande, Cortile Barile and 28" Mattone Cupola.
| Your situation | Layers | Boxes |
|---|---|---|
| Warm climate, pizza nights and weekends | 2 | 1 |
| Cold-winter climate | 3 to 4 | 2 |
| All-day or multi-day cooking | 3 to 4 | 2 |
| Commercial use | 3 to 4 | 2 of the 8 lb density |
Going from 2 layers to 3 or 4 can improve your oven’s performance by another 25% to 35%. It heats up on less wood and holds its heat longer.
Under the floor: 2 or 4 inches
The free BrickWood plans call for 2 inches of insulation under the firebrick cooking surface, set in a void in the hearth slab. That’s plenty for most owners: weekend pizza nights, the occasional bake, an afternoon or evening of cooking.
If you plan to be a heavy user, with long bread bakes, all-day roasts and cooking on stored heat into the next day, go to 4 inches. It’s an easy change: build the hearth slab form with 2x8 lumber instead of the 2x6 lumber the plans show. The extra depth goes into the insulation, and everything above the slab stays the same. The finished oven just sits a little higher, so lower the block base if you have a target height for the oven opening.
Extra insulation under the floor only pays off if the top is insulated just as well. If you go to 4 inches underneath, plan on 3 to 4 layers of blanket on top.
How to Insulate a Pizza Oven Dome or Barrel
Most builders wrap and wire the blanket in about 30 minutes, once the firebrick barrel or castable dome is finished. Your BrickWood plans show exactly where it goes on your oven.
- Gear up. Wear an N95 mask, gloves, long sleeves and safety glasses while you cut and handle the blanket.
- Cut to length. Drape the blanket over the oven and cut it with a sharp utility knife.
- Wrap the first layer. Lay it snug against the brick. Where it bunches on a curve, cut a slit so it lies flat. Butt the edges tight with no gaps.
- Wrap the next layers. Offset the seams so no seam lines up with one below it.
- Wire it down. Stretch chicken wire over the blanket and tie it off. Snug, not squashed. Crushing the blanket squeezes out the air that does the insulating.
- Stucco. Cover the wire with stucco to seal the blanket in and shape the oven.
- Finish. Once the stucco cures, finish it with paint, stone, brick or tile.
Keep the blanket dry. Cover it if rain is coming before the stucco is on. Wet blanket doesn’t insulate until it dries, and trapped water turns to steam when the oven heats up.
How to Insulate a Pizza Oven Floor
The floor insulation goes in a void built into the hearth slab, the concrete slab that sits on top of the block base.
- Dry-mix 5 to 1. Combine 5 parts perlite or vermiculite with 1 part Portland cement by volume. No sand or gravel. Wear a dust mask and mist the perlite to keep dust down.
- Add water slowly. About 1½ gallons of water for every 5 gallons of perlite or vermiculite, until every granule is damp and the mix holds together when squeezed.
- Fill the void. Spread it to the edges, tamp it lightly and screed it level with the top of the slab.
- Let it dry. About 2 days for perlite, 5 to 6 days for vermiculite. Keep rain off it.
- Add the sand bed. Spread 1 to 2 inches of all-purpose sand over the insulation to level the floor.
- Lay the firebrick cooking surface. Set the firebrick dry on the sand, with no mortar, so each brick can be nudged level.
Two 2-cubic-foot bags of perlite or vermiculite cover the hearth of any BrickWood oven. Most landscape and masonry stores carry them. Find a masonry supply near you.
Pizza Oven Insulation Mistakes to Avoid
- Skipping it. An uninsulated oven burns more wood, takes longer to heat and never holds heat for baking.
- Insulating only the top. The concrete base under an uninsulated floor pulls heat out of the firebrick cooking surface all night long.
- One layer in a cold climate. Two layers of blanket is the minimum. Cold winters call for 3 to 4.
- Gaps and lined-up seams. Heat finds every gap. Butt the edges tight and offset the seams between layers.
- Crushing the blanket. Wire it snug, not squashed, and don’t pile heavy concrete on top of it.
- Stucco straight onto the blanket. Stucco needs chicken wire to grab onto.
- Using the wrong stuff. No household fiberglass, rock wool batts, foam board or spray foam anywhere near the heat.
- Blanket under the floor. It’s too soft to support the firebrick. Use the perlite or vermiculite mix.
- Firing before it’s dry. Wet insulation turns to steam and can crack the oven. Let the floor mix dry fully, then follow our 6-day curing schedule.
- Leaving it exposed to rain. Seal it in, and protect the finished oven with a door, a chimney cap and a good pizza oven cover plan.
Going to 4 inches under the floor? You’ll need roughly twice the perlite or vermiculite of a standard 2-inch hearth.
Signs Your Pizza Oven Needs More Insulation
- The outside of the oven gets hot to the touch.
- It takes far more than an hour and a big pile of wood to reach pizza heat.
- Pizzas come out pale or soft on the bottom while the tops burn.
- The oven drops below baking heat soon after the fire burns down.
- There’s little or no usable heat the next morning.
Before you blame the insulation, check your firewood. Wet wood causes a lot of the same problems. Our firewood guide covers what to burn, and our pizza oven temperature guide shows how hot your oven should get and how to fire it.
Can you add insulation to a pizza oven later?
Sometimes, but it’s a big job. Once the stucco, stone or brick is on, the only way to add blanket is to remove the finish. Floor insulation lives inside the hearth slab, under the whole oven, so adding it later is nearly impossible without rebuilding. That’s why insulation is the last place to cut corners. Get it right the first time and your oven will reward you for decades.
Frequently Asked Questions
Does a pizza oven need insulation?
Yes. Firebrick stores heat but doesn’t insulate, so an uninsulated oven loses heat through its walls and floor. Insulation helps it heat faster, burn less wood and stay hot for hours. Never build a wood-fired oven without it.
What is the best insulation for a pizza oven?
Ceramic fiber blanket over the dome or barrel, and a 5 to 1 mix of perlite or vermiculite and Portland cement under the floor. Both are made for high heat, cost little and are easy for first-time builders.
How thick should pizza oven insulation be?
Over the top, 2 inches (2 layers of blanket) for most ovens and 3 to 4 inches in cold climates or for long cooks. Under the floor, 2 inches for most owners and 4 inches for heavy users.
How many layers of ceramic fiber blanket does a pizza oven need?
Two layers for warm climates and weekend use, 3 to 4 for cold winters or all-day cooking. One box wraps 2 layers on any BrickWood oven.
What goes under a pizza oven floor?
From the top down: the firebrick cooking surface laid dry, 1 to 2 inches of sand for leveling, 2 to 4 inches of perlite or vermiculite insulating concrete, then the concrete hearth slab.
Can you use fiberglass insulation on a pizza oven?
No. Household fiberglass, rock wool batts and foam board aren’t made for oven heat. Use ceramic fiber blanket rated for high temperatures.
Can you put ceramic fiber blanket under the floor?
No. It’s too soft to support the firebrick cooking surface. Use perlite or vermiculite insulating concrete under the floor and save the blanket for the dome or barrel.
Can you add insulation to a pizza oven later?
Only by removing the finish to add blanket, and floor insulation is nearly impossible to add without rebuilding. Install it right during the build.
Plans That Show Every Layer
Our free plans show exactly where the insulation goes on your oven, how big the hearth slab void is, and how much blanket, perlite and Portland cement to buy, with a complete materials list for every BrickWood oven and its base.
- Plans for every BrickWood oven and its base
- Complete materials and tools lists
- Emailed to you as PDFs, ready to print
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Wear an N95 mask, gloves and long sleeves when cutting ceramic fiber blanket, and a dust mask when mixing perlite or vermiculite. Always follow the plans for your specific BrickWood model.
