Cladding of a wood fired oven is the final layer placed over the fire bricks or insulation so as to provide a protective barrier and improve the aesthetic appeal. This concrete cladding is generally a 2 inch (5cm) thick concrete layer applied onto the dome. A concrete blend similar to mortar plus any concrete coloring desired should be used. Begin by placing a layer of aluminium (aluminum) foil over the oven. The foil will prevent the existing oven walls and insulation from drawing water out of the cladding before it has had the opportunity to set. Use of chicken wire oven the aluminium foil may additionally be used to improve the adhesion of the cladding to the oven. Create a 2 inch (5cm) thick layer of cladding over the foil with the use of a builders trowel. Allow the cladding to dry slightly and then continue using the builders trowel to create a smooth and uniform surface.
Aluminum foil acts as a barrier between the concrete cladding and the insulation or fire bricks. This barrier prevents water being absorbed from the concrete layer prematurely. If foil is not used, fire bricks on insulation may absorb too much moisture from the cladding and may result in a weakened outer skin. Preferably thicker foil purchased from a hardware supplier will be utilised. If this is not available general home use aluminium foil is acceptable.
The cladding layer should generally be about 1" (2.5cm) thick. The cladding is largely applied as an aesthetic layer and to provide protection to the underlying insulation. A thicker cladding layer may be applied if issues regarding water penetration or cracks developing is a perceived threat.
Due to the high heats the oven will generate, significant expansion and contraction of the inner oven dome will occur over time naturally. If this movement directly impacts upon the outer cladding layer cracks will appear sporadically in the surface. The best method to avoid this transference of movement is through the implementation of an appropriate insulation layer. Insulation is generally a soft material whether fire blanket or vermiculite cement. When this soft medium is placed between the inner oven walls and the outermost cladding, the insulation will absorb any movement from the high heats.
Outside of movement through the use of the wood fired oven, cracks may potentially form after the initial drying of the cladding layer. These cracks are generally a result of the concrete cladding mixture being too wet at application and being allowed to dry too fast. When mixing the cladding attempt to utilise the least amount of water to create a useable medium. If the oven is located in the direct sunlight, the application of a moist hessian cloth over the oven to prolong drying times may help.