Pizza oven insulation

wood fired pizza oven requires an insulation lay on top on the initial internal dome of bricks and under the hearth so as to improve the heat retaining properties of the oven. The insulation can be made out of a number of different materials which are refractory heat resistant and have insulation properties. Generally the insulation is either fire blanket which is a material usually used with industrial ovens, a loose mixture of insulating material which is loosely packed around the oven, or an insulating mortar which is a mixture of cement and vermiculite or pertiteInsulating fire bricks may sometimes be used however these are generally utilised for hobby kilns or industrial ovens.

Heat generated in the oven vault is absorbed by the walls which are generally made of either fire brick or cob. Fire brick in particular is excellent at absorbing the heat and radiating it back into the oven. To prevent the bricks radiating the heat in the opposite direction into the open environment, insulation must be placed on the outside of the oven wall to prevent this dissipation. With the added insulation the oven is able to remain hot for a long period of time. If the oven is built without insulation the time required to heat the vault will be increased and the heat generated by the fire will quickly diminish.

Insulation Type

  • Perlite or vermiculite can be used for dry and loose form of heat insulation.
  • Ceramic fiber blankets.
  • Perlite and vermiculite cement under the hearth or over the dome.
  • Insulating fire bricks

Under Hearth Insulation

Insulation is required under the oven hearth in addition to over the oven dome. Although heat generally rises, heat will be drawn down through the hearth particularly if the foundation is a solid material rather than gravel. The hearth insulation is placed upon the oven foundation which is generally a reinforced concrete slab.

Perlite or Vermiculite Cement

  1. Build a simple temporary wood structure on the foundation to contain the cement insulation until it has dried and cured. The cement insulation should be build to a thickness of at least 4inches (10cm).
  2. Create a mixture of vermiculite or perlite and cement in the ratio of 5 : 1. Mix the materials with a small amount of water in a wheelbarrow until consistently wet. As with dome insulation of cement and perlite or vermiculite, do not use a cement mixer as it may damage the materials.
  3. Place the cement mixture with reinforcing steel on the oven foundation in the wood contained area. Make the cement as level as possible with the use of a builder trowel.
  4. Once the insulation cement has dried remove the temporary wood structure.
  5. Upon this foundation cement the hearth can now be constructed.
Portland CementPerlite or Vermiculite
1 part5 parts

Insulating Fire Bricks

  1. Using fire clay mortar lay insulating fire bricks directly upon the level oven foundation.
  2. Allow the mortar to dry and cure.
  3. The oven hearth can be constructed directly upon the insulating fire bricks.

Glass Bottles

For cob pizza ovens a cheaper alternative to under hearth insulation is often sought. In this instance many builders will utilise empty glass bottles laid down to create the necessary air space. The glass bottles are then covered with either cob or sand. The hearth of fire bricks or clay is built directly upon the insulation.

Dome Insulation

Once the internal brick wall is finished construction of the insulation layer may begin. Insulation is required to ensure the oven retains heat so as to rise to a high temperature and maintain the temperature for a long period. Heat up times are important both from the perspective of speed of use and from cost of operations through firewood expenditure. The below table gives an indication of insulation thickness, heat up and cool down times for an oven constructed with fire brick and vermiculite cement as the insulation.

Internal Dome ThicknessInsulation ThicknessHeat Up DurationCool Down Duration
4" (10cm)4" (10cm)1 hour12 hours
4" (10cm)2" (5cm)2 hour6 hours
2" (10cm)4" (5cm)30 minutes4 hours
6" (15cm)6" (15cm)2 hour24 hours

Fire Blanket Insulation

Fire blanket is a heat resistant material commonly used for industrial ovens. The material comes in many different grades depending on the properties required such as the heat tolerance and insulating performance. The lowest grade available is generally sufficient for wood fired ovens as the temperatures realised although high are not extreme. Higher grades are used for industrial application with extreme temperatures which will not be found the the traditional oven. Ceramic insulation due to its effectiveness is generally the more expensive option. Depending on the grade of the insulation the blankets may cost around $50 for a 13mm x 610mm x 1460mm piece. Due to the quality however the thickness of the insulation layer may be smaller than other options. A thickness of 1 to 2 inches (2.5 to 5cm) is recommended. Personal protection is also recommended due to the hazardous danger the material creates when handled. Small sharp dust particles may be created which are damaging to hands, eyes, lungs and irritating to the skin. For this reason it is recommended that when installing the user should ware a long sleeved shirt, a respiratory mask and eye protection.

  1. Cut a piece of fire blanket that may be placed around the circumference of the oven.
  2. Cut a similar sized piece of chicken wire and place that oven the blanket to hold it into place.
  3. Use wire to hold the whole structure stable.
  4. Continue to cover the oven in a minimum 1 inch layer of insulation.
  5. Be careful when placing additional layers of material on top of the ceramic insulation to not compact or squash the blanket. The insulating properties of the blanket are created by the air held within. If the material is compacted the ability for the blanket to function as intended is reduced. The insulation will need to be covered in a final cladding layer however particular care must be taken when applying wet cement or mortar.

Perlite or Vermiculite Cement

Perlite and vermiculite are products commonly used in horticulture and hydroponics. The material also has good insulation properties. When mixing the materials do not utilise a regular builders cement mixer. The harsh mechanical action of mixer is likely to damage the soft insulating particles.

  1. Cover the oven dome in aluminium foil. The foil is to prevent the existing oven structure from drawing water from the cement mix and hastening the curing process.
  2. Mix perlite or vermiculite with cement and lime at the appropriate rate (13:1:1) with some water to create the insulating material.
  3. Place a layer of about 1 inch (2.5cm) of the cement insulation material over the brick or on top of the fire blanket. If placing on insulating blanket additional care must be taken not to compress the blanket.
  4. Let the insulating layer harden and then apply additional layers.
  5. Build up the insulation to a minimum of 4 inches. This will require multiple applications between drying.
Portland CementPerlite or VermiculiteLime
1 part13 parts1 part

Loose Materials Such as Perlite, Vermiculite or Ceramic Fiber

Perlite, vermiculite or ceramic fiber pieces may be used in its loose form rather than as part of a cement mix if desired. Disadvantages of this approach exist in that the material may be messy or escape if small gaps exist in the containing structure. This approach is generally best used only if the oven dome will be enclosed in a rectangular brick walled structure. Benefits of this approach is that the oven dome will be included within a walled brick structure which provides protection from the weather and in particular water. Ideally the loose material will create an insulating layer of 4 inches (10cm) thick or larger. Vermiculite may be purchased from gardening or hydroponics suppliers for around $20 for a 100 liter bag.

  1. Once the oven dome is complete, construct a four walled brick structure around the dome. The walls will need to surround the dome and chimney entirely without any gaps through which the insulating material might escape. Ensure the walls are at least 4inches (10cm) away from the inner dome. Additionally the walls will need to be sufficiently high to allow 4 inches (10cm) of insulating material to protrude above the oven dome.
  2. Pour vermiculite, perlite or other refractory insulating materials into the space created between the outer walls and the oven vault walls. It is recommended that the insulating material is of a middle grade which is easy to handle, neither powder nor extremely large pieces. Ensure that no material is escaping into the oven vault, the chimney, or outside the containing outer walls.
  3. A roof will need to be constructed to contain the insulating material and through which the chimney will protrude. Ideally the roof will comprise of a tiled structure however this will add to the build costs.

Insulating Fire Bricks

Insulating fire brick is a form of fire brick which is less dense and comprises of many small air bubbles which provide insulating properties. As with fire brick, insulating fire bricks are a purpose built refractory products which may withstand very high heat without suffering structural damage. The insulating bricks will be laid directly on top of the existing fire brick dome.

  1. Starting from the bottom of the dome laying a single layer or bricks directly up against the dome.
  2. Ideally utilise fire clay mortar between the laid insulating bricks and between the insulating bricks and the existing oven dome.
  3. Continue laying bricks to cover the existing oven dome.
  4. Insulating bricks may be cut with a hand saw if a smaller piece is required for the capping stone.
  5. A single layer of insulating fire bricks with a final cladding layer will generally be sufficient. Additional insulation in the form of insulating fire bricks or fire blanket may be added if desired.

Obtaining the Insulation Material

Insulating materials are available from different suppliers depending upon the material sought and the locality of the construction. In general materials like perlite and vermiculite are available from hardware, gardening or hydroponics suppliers due to the use of the material in plant cultivation. Materials such as insulating fire brick or ceramic blanket are available from hardware or refractory product suppliers. These materials are generally used in the construction of fireplaces or kilns.


Card image cap
How to Build a Pizza Oven

A traditional wood-fired pizza oven, or more commonly known as masonry oven, is a type of ...

Card image cap
How to construct a pizza oven dome out of cob

Cob oven on a stone foundationA cob pizza oven dome is a basic structure built&n...

Card image cap
Insulating dome pizza oven

The materials you use to build your oven determines how long the oven will last. The material of the...

Dome wall thickness

The thicker the walls of a wood fired pizza oven the greater the thermal mass the oven wil...

Using castable refractory cement between bricks?

Hi, newbee "mason" here. I have castable high temp mortar that I tried to use to butter between the ...

How to clean a brick hearth

What is the best type of bristle brush to clean the brick hearth in my Wood Fired Oven?

Card image cap
How to cook with a wood fired pizza oven

Further information: How to build a pizza ovenCooking a pizza in a pizza oven is always a fun e...

Card image cap
How to build a pizza oven hearth

Round pizza oven hearthIn a wood fired pizza oven the hearth is the section upon which the...

Card image cap
Purchasing a pizza oven

Further information: How to build a pizza ovenA pizza oven may be either built from raw materials or...

Card image cap
Types of cement

Further information: How to build a pizza ovenWhite cementThere are several ordinary cements in...

Card image cap
How to cook steak in a pizza oven

See: How to cook with a wood fired pizza oven1" (1 inch) = 2.5cm.Thickness1/2"3/4"1"1 1/4"1 1/2...

Card image cap
How to build a wood fired oven door

Further information: How to build a pizza ovenA door is a useful component of any tradition woo...

Card image cap
How to build a pizza oven shelter

Pizza oven shelterWhen building a pizza oven in an external location, it is important to c...

Card image cap
How to fire a wood fired pizza oven

Further information: How to build a pizza ovenWhen starting the initial fire in the oven be sur...

Card image cap
Fire bricks

Fire bricksFire bricks are an essential material in the building of a long-lasting, effective pizza ...

Card image cap
How to clad a pizza oven

Further information: How to build a pizza ovenCladding of a wood fired oven is the final layer ...

Card image cap
Build a pizza oven foundation out of brick

Building a pizza oven foundation out of brick starts with preparing the location. Fir...

Card image cap
Types of wood fired pizza ovens

Further information: How to build a pizza ovenBarrel VaultBarrel vault ovens are usually made o...

Card image cap
Common problems with pizza ovens

Further information: How to build a pizza ovenWhy my oven is not hot enough?The temperature pot...

Card image cap
Sourcing materials for building a wood fired oven

Sourcing materials for building a pizza oven can be difficult due to the types of material...

Card image cap
Pizza oven plans

A number of building plans exist due to the wide range of techniques by which a wood fired pizza ove...

Card image cap
What is oven cladding

Oven cladding is the process of applying a mortar or mud material to a wood fired oven to create a t...

Card image cap
Wood fired pizza oven building plans

Traditional wood fired ovens are notoriously challenging and fun to construct, and unique in charact...

Card image cap
History of pizza ovens

Wood-fired pizza ovens have long been existent for thousands of years. This type of oven has be...

Card image cap
Igloo dome vs barrel vault dome pizza ovens

Generally the determination of building an igloo dome or barrel vault pizza oven...

Card image cap
Building plans for a 42 inch igloo brick pizza oven

42inch pizza ovenBuilding plans PDFBuilding plans for a 42 inch igloo brick pizza oven.pdfFurther in...

Card image cap
How to install pizza oven insulation

Further information: How to build a pizza ovenThe insulation of a wood fired oven in its constr...

Card image cap
Different Bricks and quality testing methods

How to test good quality bricks!Brick is one of the important materials in making pizza oven. There ...

More Forum Threads