Insulating Your Wood-Fired Oven
It can be a bit confusing at first to figure out how to properly insulate your pizza oven. It makes good sense to check out the options, particularly if you live in a cold climate, so that your oven will be very energy efficient and keep the heat in for a long cooking cycle.
Whether your project calls for a concrete masonry slab or a metal frame stand, the most common way of insulating the oven from below is a 1.5″ – 2″ layer of Super Isol Boards. These are boards made of Calcium Silicate with a great compression strength, so they can hold the weight of a pizza oven. They are light, and are easily cut and placed under the oven. You will need 3 boards for a medium size oven, for example, a Model 90 or a Model 100. Or you can use a 4″ layer of vermiculite and cement mix under the oven. You can buy vermiculite at Home Depot or a garden/plant center in 4 cubic foot bags. Request vermiculite without silicon coating and definitely wear a respirator or mask when handling vermiculite since it produces a lot of dust. Another alternative is a layer of medium duty fire bricks. Keep in mind that these last two options will mean more labor, so include that in your cost comparison when planning for your pizza oven. Isol Boards are porous, absorbing water very easily and you must enclose them completely when building the structure around your oven, so that they are not exposed to the elements. You really don’t want any moisture absorbed in your wood fired oven, because water would steam at higher temperatures causing cracks. The Super Isol boards we offer are high-quality to avoid the problems we’ve heard others encounter with cheaper versions of this product.
To insulate the top of the wood fired oven you will use the thermal insulating blanket provided in your oven kit. Wrapping this over the dome will ensure that there is no loss of heat. If you live in colder climates or if you just want to add extra insulation then fill the cavity between your oven and the masonry walls you built around it with lose vermiculite leaving an air gap at the top. If you are planning a mediterranean or adobe style oven, i.e. without the masonry structure around it, then you do need to coat the oven and the blanket with a 5″ mix of vermiculite and cement for extra protection and thermal mass. Then you can stucco and paint with exterior stucco paint to make it waterproof.
Insulating properly will also mean saving on wood in the long run, although a wood fired oven is very thrifty in its consumption compared to a fireplace. It will insure many years of happy cooking!
Buon appetito from us all at Los Angeles Ovenworks.