Barrel style oven

[Dave Sickles]

Do I mortar the bottom course of fire brick to the hearth?

[SableSprings]

The concrete of the hearth must be insulated from the oven's base bricks (cooking floor and vault base). The two normal means are insulating ceramic board or a 5:1 perlcrete/vermicrete layer (5 parts perlite or vermiculite and 1 part Portland cement). So, on top of your concrete stand (hearth), you place an insulation layer, and then the oven's cooking floor and outer vault (or dome) base on top of the insulation. If you simply put your oven's firebrick on the concrete hearth, the concrete becomes a giant heat sink and your oven will be very difficult to heat up to pizza temps (and will very likely damage the base).

The firebrick of the cooking floor is not mortared to the insulation layer nor are the outer oven bricks. The oven will actually expand and contract during firing cycles, so mortar at the insulation/firebrick interface is a waste of time. Don't forget that you will need to buttress (or steel strap) the lower perimeter of a vault oven since the structure is not as stable as a dome. Also it is recommended to put your back wall inside the vault (not as a cap on the end). If your insulation layer (or ceramic board is not level), you can use a thin layer of damp sand and fire clay on top of the insulation to set your cooking floor level.

Here's a post with a great cross-section picture to help further your understanding of the layers.

https://community.fornobravo.com/for...901#post406901

Hope that helps.

[Dave Sickles]

That helps out alot..is there a pic of the buttress?

[UtahBeehiver]

Do a search on the forum under "Other Type of Ovens" there are several barrels out there with various ways to buttress. Is there a particular reason you are doing a barrel? A dome in my opinion does not require buttressing and is self supporting and in ways easier to build than barrels, sans buttressing. Mike is spot on in his reasoning way "not" to mortar or place bricks directly on concrete hearth floor. If you have not done so yet, download the Forno Bravo eplans for Pompeii oven, they are only a $3 and although the plans focus around dome ovens there is a lot of info for using and building a WFO. One more item, if you pursue the barrel config, the end walls are place inside the barrel structure not the outside, the expansion of the barrel will push the walls out if placed outside the barrel.

Tscarburough, did a nice barrel, you can peruse his thread for pics.

[Dave Sickles]

I'm simply doing the barrel because I like the look,my floor is insulated,my oven floor is layed,now to start the barrel its 2 brick high then starts the arch...I was jst wondering if that bottom row gets mortared to the floor

[UtahBeehiver]

As Mike said, no.